N-CSRS

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UNITED STATES SECURITIES AND EXCHANGE COMMISSION 

Washington, DC  20549

FORM N-CSR

CERTIFIED SHAREHOLDER REPORT OF REGISTERED 

MANAGEMENT INVESTMENT COMPANIES

Investment Company Act file number 811-04815

Ultra Series Fund 

(Exact name of registrant as specified in charter)

550 Science Drive, Madison, WI  53711 

(Address of principal executive offices)(Zip code)

Steve J. Fredricks 

Chief Legal Officer & Chief Compliance Officer 

550 Science Drive

Madison, WI  53711 

(Name and address of agent for service)

Registrant's telephone number, including area code:  608-274-0300

Date of fiscal year end:  December 31

Date of reporting period:  June 30, 2025

Form N-CSR is to be used by management investment companies to file reports with the Commission not later than 10 days after the transmission to stockholders of any report that is required to be transmitted to stockholders under Rule 30e-1 under the Investment Company Act of 1940 (17 CFR 270.30e-1). The Commission may use the information provided on Form N-CSR in its regulatory, disclosure review, inspection, and policymaking roles.

A registrant is required to disclose the information specified by Form N-CSR, and the Commission will make this information public. A registrant is not required to respond to the collection of information contained in Form N-CSR unless the Form displays a currently valid Office of Management and Budget ("OMB") control number. Please direct comments concerning the accuracy of the information collection burden estimate and any suggestions for reducing the burden to Secretary, Securities and Exchange Commission, 450 Fifth Street, NW, Washington, DC  20549-0609. The OMB has reviewed this collection of information under the clearance requirements of 44 U.S.C. § 3507.

Item 1. Reports to Shareholders.

  Semi-Annual Shareholder Report June 30, 2025

Conservative Allocation Fund Class I

Fund Overview 

This semi-annual shareholder report contains important information about Conservative Allocation Fund Class I for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$17	0.33%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$46,984,089
# of Portfolio Holdings	20
Portfolio Turnover Rate	19%
Total Advisory Fees Paid	$70,831

What does the Fund invest in?  

The Fund invests primarily in shares of other registered investment companies. The Fund’s total net assets will be allocated among various asset classes and underlying funds with target allocations over time of approximately 35% equity investments and 65% fixed income investments.

Top Ten Holdings (% of Net Assets) 

Madison Core Bond Fund, Class R6	42.4%
Schwab Intermediate-Term U.S. Treasury ETF	8.5%
Madison Large Cap Fund, Class R6	8.5%
Janus Henderson Mortgage-Backed Securities ETF	7.8%
Invesco S&P 500 Quality ETF	6.6%
Vanguard Information Technology ETF	3.1%
Vanguard FTSE Europe ETF	2.9%
iShares MSCI Emerging Markets Asia ETF	2.6%
Vanguard Short-Term Corporate Bond ETF	2.1%
Distillate U.S. Fundamental Stability & Value ETF	2.1%

Portfolio Allocation (% of Net Assets) 

Investment Companies	50.9%
Exchange Traded Funds	47.9%
Short-Term Investments	2.8%
Other Assets and Liabilities, Net	(1.6%)

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089 

Conservative Allocation Fund Class I

  Semi-Annual Shareholder Report June 30, 2025

Conservative Allocation Fund Class II

Fund Overview 

This semi-annual shareholder report contains important information about Conservative Allocation Fund Class II for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class II	$29	0.58%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$46,984,089
# of Portfolio Holdings	20
Portfolio Turnover Rate	19%
Total Advisory Fees Paid	$70,831

What does the Fund invest in?  

The Fund invests primarily in shares of other registered investment companies. The Fund’s total net assets will be allocated among various asset classes and underlying funds with target allocations over time of approximately 35% equity investments and 65% fixed income investments.

Top Ten Holdings (% of Net Assets) 

Madison Core Bond Fund, Class R6	42.4%
Schwab Intermediate-Term U.S. Treasury ETF	8.5%
Madison Large Cap Fund, Class R6	8.5%
Janus Henderson Mortgage-Backed Securities ETF	7.8%
Invesco S&P 500 Quality ETF	6.6%
Vanguard Information Technology ETF	3.1%
Vanguard FTSE Europe ETF	2.9%
iShares MSCI Emerging Markets Asia ETF	2.6%
Vanguard Short-Term Corporate Bond ETF	2.1%
Distillate U.S. Fundamental Stability & Value ETF	2.1%

Portfolio Allocation (% of Net Assets) 

Investment Companies	50.9%
Exchange Traded Funds	47.9%
Short-Term Investments	2.8%
Other Assets and Liabilities, Net	(1.6%)

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089 

Conservative Allocation Fund Class II

  Semi-Annual Shareholder Report June 30, 2025

Moderate Allocation Fund Class I

Fund Overview 

This semi-annual shareholder report contains important information about Moderate Allocation Fund Class I for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$17	0.33%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$101,959,298
# of Portfolio Holdings	20
Portfolio Turnover Rate	25%
Total Advisory Fees Paid	$153,356

What does the Fund invest in?  

The Fund invests primarily in shares of other registered investment companies. The Fund’s total net assets will be allocated among various asset classes and underlying funds with target allocations over time of approximately 60% equity investments and 40% fixed income investments.

Top Ten Holdings (% of Net Assets) 

Madison Core Bond Fund, Class R6	27.2%
Madison Large Cap Fund, Class R6	13.8%
Invesco S&P 500 Quality ETF	9.7%
Vanguard FTSE Europe ETF	5.5%
Vanguard Information Technology ETF	5.1%
iShares MSCI Emerging Markets Asia ETF	4.8%
Janus Henderson Mortgage-Backed Securities ETF	4.2%
Distillate U.S. Fundamental Stability & Value ETF	3.6%
iShares Core S&P Small-Cap ETF	3.2%
Schwab Intermediate-Term U.S. Treasury ETF	3.1%

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	54.7%
Investment Companies	42.1%
Short-Term Investments	6.7%
Other Assets and Liabilities, Net	(3.5%)

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089 

Moderate Allocation Fund Class I

  Semi-Annual Shareholder Report June 30, 2025

Moderate Allocation Fund Class II

Fund Overview 

This semi-annual shareholder report contains important information about Moderate Allocation Fund Class II for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class II	$29	0.58%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$101,959,298
# of Portfolio Holdings	20
Portfolio Turnover Rate	25%
Total Advisory Fees Paid	$153,356

What does the Fund invest in?  

The Fund invests primarily in shares of other registered investment companies. The Fund’s total net assets will be allocated among various asset classes and underlying funds with target allocations over time of approximately 60% equity investments and 40% fixed income investments.

Top Ten Holdings (% of Net Assets) 

Madison Core Bond Fund, Class R6	27.2%
Madison Large Cap Fund, Class R6	13.8%
Invesco S&P 500 Quality ETF	9.7%
Vanguard FTSE Europe ETF	5.5%
Vanguard Information Technology ETF	5.1%
iShares MSCI Emerging Markets Asia ETF	4.8%
Janus Henderson Mortgage-Backed Securities ETF	4.2%
Distillate U.S. Fundamental Stability & Value ETF	3.6%
iShares Core S&P Small-Cap ETF	3.2%
Schwab Intermediate-Term U.S. Treasury ETF	3.1%

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	54.7%
Investment Companies	42.1%
Short-Term Investments	6.7%
Other Assets and Liabilities, Net	(3.5%)

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089 

Moderate Allocation Fund Class II

  Semi-Annual Shareholder Report June 30, 2025

Aggressive Allocation Fund Class I

Fund Overview 

This semi-annual shareholder report contains important information about Aggressive Allocation Fund Class I for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$17	0.32%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$41,383,479
# of Portfolio Holdings	19
Portfolio Turnover Rate	27%
Total Advisory Fees Paid	$59,918

What does the Fund invest in?  

The Fund invests primarily in shares of other registered investment companies. The Fund’s total net assets will be allocated among various asset classes and underlying funds with target allocations over time of approximately 80% equity investments and 20% fixed income investments.

Top Ten Holdings (% of Net Assets) 

Madison Large Cap Fund, Class R6	16.5%
Madison Core Bond Fund, Class R6	13.9%
Invesco S&P 500 Quality ETF	12.4%
Vanguard FTSE Europe ETF	8.2%
Vanguard Information Technology ETF	7.3%
Distillate U.S. Fundamental Stability & Value ETF	6.8%
iShares MSCI Emerging Markets Asia ETF	6.3%
SPDR S&P Bank ETF	4.5%
iShares Core S&P Small-Cap ETF	4.1%
Vanguard FTSE All-World ex-U.S. ETF	3.5%

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	64.5%
Investment Companies	31.8%
Short-Term Investments	8.7%
Other Assets and Liabilities, Net	(5.0%)

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089 

Aggressive Allocation Fund Class I

  Semi-Annual Shareholder Report June 30, 2025

Aggressive Allocation Fund Class II

Fund Overview 

This semi-annual shareholder report contains important information about Aggressive Allocation Fund Class II for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class II	$29	0.57%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$41,383,479
# of Portfolio Holdings	19
Portfolio Turnover Rate	27%
Total Advisory Fees Paid	$59,918

What does the Fund invest in?  

The Fund invests primarily in shares of other registered investment companies. The Fund’s total net assets will be allocated among various asset classes and underlying funds with target allocations over time of approximately 80% equity investments and 20% fixed income investments.

Top Ten Holdings (% of Net Assets) 

Madison Large Cap Fund, Class R6	16.5%
Madison Core Bond Fund, Class R6	13.9%
Invesco S&P 500 Quality ETF	12.4%
Vanguard FTSE Europe ETF	8.2%
Vanguard Information Technology ETF	7.3%
Distillate U.S. Fundamental Stability & Value ETF	6.8%
iShares MSCI Emerging Markets Asia ETF	6.3%
SPDR S&P Bank ETF	4.5%
iShares Core S&P Small-Cap ETF	4.1%
Vanguard FTSE All-World ex-U.S. ETF	3.5%

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	64.5%
Investment Companies	31.8%
Short-Term Investments	8.7%
Other Assets and Liabilities, Net	(5.0%)

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089 

Aggressive Allocation Fund Class II

  Semi-Annual Shareholder Report June 30, 2025

Diversified Income Fund Class I

Fund Overview 

This semi-annual shareholder report contains important information about Diversified Income Fund Class I for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$14	0.27%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$144,073,661
# of Portfolio Holdings	16
Portfolio Turnover Rate	16%
Total Advisory Fees Paid	$180,875

What does the Fund invest in?  

The Fund primarily invests in shares of other registered investment companies, diversifying across various asset classes according to an asset allocation approximately 60% in equity investments and 40% in fixed income investments.

Top Ten Holdings (% of Net Assets) 

Madison Short-Term Strategic Income ETF	22.4%
Madison Dividend Value ETF	19.0%
Madison Aggregate Bond ETF	17.9%
Madison Covered Call ETF	15.7%
SPDR Portfolio High Yield Bond ETF	10.0%
Janus Henderson Mortgage-Backed Securities ETF	4.9%
Global X MLP ETF	4.0%
Schwab U.S. Dividend Equity ETF	3.4%
iShares 5-10 Year Investment Grade Corporate Bond ETF	2.0%
Federal National Mortgage Association, 7.000%, due 11/01/31	0.0%

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	99.4%
Short-Term Investments	1.4%
Mortgage Backed Securities	0.0%
Commercial Mortgage-Backed Securities	0.0%
Other Assets and Liabilities, Net	(0.8%)

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089 

Diversified Income Fund Class I

  Semi-Annual Shareholder Report June 30, 2025

Diversified Income Fund Class II

Fund Overview 

This semi-annual shareholder report contains important information about Diversified Income Fund Class II for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class II	$26	0.52%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$144,073,661
# of Portfolio Holdings	16
Portfolio Turnover Rate	16%
Total Advisory Fees Paid	$180,875

What does the Fund invest in?  

The Fund primarily invests in shares of other registered investment companies, diversifying across various asset classes according to an asset allocation approximately 60% in equity investments and 40% in fixed income investments.

Top Ten Holdings (% of Net Assets) 

Madison Short-Term Strategic Income ETF	22.4%
Madison Dividend Value ETF	19.0%
Madison Aggregate Bond ETF	17.9%
Madison Covered Call ETF	15.7%
SPDR Portfolio High Yield Bond ETF	10.0%
Janus Henderson Mortgage-Backed Securities ETF	4.9%
Global X MLP ETF	4.0%
Schwab U.S. Dividend Equity ETF	3.4%
iShares 5-10 Year Investment Grade Corporate Bond ETF	2.0%
Federal National Mortgage Association, 7.000%, due 11/01/31	0.0%

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	99.4%
Short-Term Investments	1.4%
Mortgage Backed Securities	0.0%
Commercial Mortgage-Backed Securities	0.0%
Other Assets and Liabilities, Net	(0.8%)

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089 

Diversified Income Fund Class II

  Semi-Annual Shareholder Report June 30, 2025

Core Bond Fund Class I

Fund Overview 

This semi-annual shareholder report contains important information about Core Bond Fund Class I for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$29	0.58%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$53,754,931
# of Portfolio Holdings	254
Portfolio Turnover Rate	8%
Total Advisory Fees Paid	$172,883

What does the Fund invest in?  

The Fund invests primary in fixed income securities such as Corporate, U.S. Government and Foreign debt securities. In addition the fund also invested in asset backed, mortgage-backed and commercial mortgage-backed securities.

Top Ten Holdings (% of Net Assets) 

Federal Home Loan Mortgage Corp., 2.500%, due 01/01/52	1.5%
U.S. Treasury Bonds, 6.625%, due 02/15/27	1.5%
U.S. Treasury Notes, 4.375%, due 05/15/34	1.4%
U.S. Treasury Bonds, 4.500%, due 05/15/38	1.4%
U.S. Treasury Notes, 4.000%, due 02/15/34	1.4%
U.S. Treasury Notes, 2.875%, due 05/15/28	1.4%
U.S. Treasury Notes, 2.625%, due 02/15/29	1.3%
U.S. Treasury Bonds, 4.250%, due 08/15/54	1.3%
U.S. Treasury Bonds, 3.750%, due 08/15/41	1.3%
Federal National Mortgage Association, 4.500%, due 08/01/52	1.1%

Portfolio Allocation (% of Net Assets) 

Mortgage Backed Securities	41.1%
Corporate Notes and Bonds	25.7%
U.S. Government and Agency Obligations	18.9%
Collateralized Mortgage Obligations	6.5%
Foreign Corporate Bonds	3.1%
Short-Term Investments	2.5%
Asset Backed Securities	1.2%
Commercial Mortgage-Backed Securities	0.8%
Other Assets and Liabilities, Net	0.2%

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089 

Core Bond Fund Class I

  Semi-Annual Shareholder Report June 30, 2025

Core Bond Fund Class II

Fund Overview 

This semi-annual shareholder report contains important information about Core Bond Fund Class II for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class II	$42	0.83%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$53,754,931
# of Portfolio Holdings	254
Portfolio Turnover Rate	8%
Total Advisory Fees Paid	$172,883

What does the Fund invest in?  

The Fund invests primary in fixed income securities such as Corporate, U.S. Government and Foreign debt securities. In addition the fund also invested in asset backed, mortgage-backed and commercial mortgage-backed securities.

Top Ten Holdings (% of Net Assets) 

Federal Home Loan Mortgage Corp., 2.500%, due 01/01/52	1.5%
U.S. Treasury Bonds, 6.625%, due 02/15/27	1.5%
U.S. Treasury Notes, 4.375%, due 05/15/34	1.4%
U.S. Treasury Bonds, 4.500%, due 05/15/38	1.4%
U.S. Treasury Notes, 4.000%, due 02/15/34	1.4%
U.S. Treasury Notes, 2.875%, due 05/15/28	1.4%
U.S. Treasury Notes, 2.625%, due 02/15/29	1.3%
U.S. Treasury Bonds, 4.250%, due 08/15/54	1.3%
U.S. Treasury Bonds, 3.750%, due 08/15/41	1.3%
Federal National Mortgage Association, 4.500%, due 08/01/52	1.1%

Portfolio Allocation (% of Net Assets) 

Mortgage Backed Securities	41.1%
Corporate Notes and Bonds	25.7%
U.S. Government and Agency Obligations	18.9%
Collateralized Mortgage Obligations	6.5%
Foreign Corporate Bonds	3.1%
Short-Term Investments	2.5%
Asset Backed Securities	1.2%
Commercial Mortgage-Backed Securities	0.8%
Other Assets and Liabilities, Net	0.2%

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089

Core Bond Fund Class II

  Semi-Annual Shareholder Report June 30, 2025

Large Cap Value Fund Class I

Fund Overview 

This semi-annual shareholder report contains important information about Large Cap Value Fund Class I for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$32	0.63%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$164,797,008
# of Portfolio Holdings	40
Portfolio Turnover Rate	7%
Total Advisory Fees Paid	$521,825

What does the Fund invest in?  

The Fund invests primarily in common stocks of large-cap companies as defined as those in the Russell 1000^® Value Index. The Fund targets to maintain at least 80% of its net assets in such stocks.

Top Ten Holdings (% of Net Assets) 

CME Group, Inc.	4.3%
Automatic Data Processing, Inc.	4.0%
Blackrock, Inc.	3.9%
Morgan Stanley	3.8%
Honeywell International, Inc.	3.8%
NextEra Energy, Inc.	3.5%
Home Depot, Inc.	3.5%
Texas Instruments, Inc.	3.5%
Johnson & Johnson	3.3%
Fastenal Co.	3.3%

Sector Allocation (% of Net Assets) 

Industrials	20.3%
Financials	20.0%
Health Care	14.1%
Energy	8.9%
Consumer Discretionary	8.7%
Information Technology	8.1%
Consumer Staples	7.3%
Utilities	3.6%
Equity Real Estate Investment Trusts (REITs)	2.8%
Communication Services	2.7%
Materials	1.9%
Short-Term Investments	1.6%
Other Assets and Liabilities, Net	0.0%

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089

Large Cap Value Fund Class I

  Semi-Annual Shareholder Report June 30, 2025

Large Cap Value Fund Class II

Fund Overview 

This semi-annual shareholder report contains important information about Large Cap Value Fund Class II for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class II	$44	0.88%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$164,797,008
# of Portfolio Holdings	40
Portfolio Turnover Rate	7%
Total Advisory Fees Paid	$521,825

What does the Fund invest in?  

The Fund invests primarily in common stocks of large-cap companies as defined as those in the Russell 1000^® Value Index. The Fund targets to maintain at least 80% of its net assets in such stocks.

Top Ten Holdings (% of Net Assets) 

CME Group, Inc.	4.3%
Automatic Data Processing, Inc.	4.0%
Blackrock, Inc.	3.9%
Morgan Stanley	3.8%
Honeywell International, Inc.	3.8%
NextEra Energy, Inc.	3.5%
Home Depot, Inc.	3.5%
Texas Instruments, Inc.	3.5%
Johnson & Johnson	3.3%
Fastenal Co.	3.3%

Sector Allocation (% of Net Assets) 

Industrials	20.3%
Financials	20.0%
Health Care	14.1%
Energy	8.9%
Consumer Discretionary	8.7%
Information Technology	8.1%
Consumer Staples	7.3%
Utilities	3.6%
Equity Real Estate Investment Trusts (REITs)	2.8%
Communication Services	2.7%
Materials	1.9%
Short-Term Investments	1.6%
Other Assets and Liabilities, Net	0.0%

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089

Large Cap Value Fund Class II

  Semi-Annual Shareholder Report June 30, 2025

Large Cap Growth Fund Class I

Fund Overview 

This semi-annual shareholder report contains important information about Large Cap Growth Fund Class I for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$41	0.83%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$180,760,334
# of Portfolio Holdings	31
Portfolio Turnover Rate	15%
Total Advisory Fees Paid	$769,153

What does the Fund invest in?  

The Fund invests primarily in common stocks of large-cap companies as defined as those in the Russell 1000^® Growth Index. The Fund targets to maintain at least 80% of its net assets in such stocks.

Top Ten Holdings (% of Net Assets) 

Arch Capital Group Ltd.	6.0%
Amazon.com, Inc.	5.3%
Alphabet, Inc., Class C	5.2%
Texas Instruments, Inc.	5.0%
Ferguson Enterprises, Inc.	4.6%
Fiserv, Inc.	4.2%
Visa, Inc., Class A	3.9%
Progressive Corp.	3.8%
PACCAR, Inc.	3.8%
Parker-Hannifin Corp.	3.7%

Sector Allocation (% of Net Assets) 

Financials	26.1%
Information Technology	20.0%
Industrials	17.6%
Consumer Discretionary	15.5%
Health Care	11.7%
Communication Services	7.1%
Short-Term Investments	2.0%
Other Assets and Liabilities, Net	0.0%

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089

Large Cap Growth Fund Class I

  Semi-Annual Shareholder Report June 30, 2025

Large Cap Growth Fund Class II

Fund Overview 

This semi-annual shareholder report contains important information about Large Cap Growth Fund Class II for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class II	$54	1.08%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$180,760,334
# of Portfolio Holdings	31
Portfolio Turnover Rate	15%
Total Advisory Fees Paid	$769,153

What does the Fund invest in?  

The Fund invests primarily in common stocks of large-cap companies as defined as those in the Russell 1000^® Growth Index. The Fund targets to maintain at least 80% of its net assets in such stocks.

Top Ten Holdings (% of Net Assets) 

Arch Capital Group Ltd.	6.0%
Amazon.com, Inc.	5.3%
Alphabet, Inc., Class C	5.2%
Texas Instruments, Inc.	5.0%
Ferguson Enterprises, Inc.	4.6%
Fiserv, Inc.	4.2%
Visa, Inc., Class A	3.9%
Progressive Corp.	3.8%
PACCAR, Inc.	3.8%
Parker-Hannifin Corp.	3.7%

Sector Allocation (% of Net Assets) 

Financials	26.1%
Information Technology	20.0%
Industrials	17.6%
Consumer Discretionary	15.5%
Health Care	11.7%
Communication Services	7.1%
Short-Term Investments	2.0%
Other Assets and Liabilities, Net	0.0%

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089

Large Cap Growth Fund Class II

  Semi-Annual Shareholder Report June 30, 2025

Mid Cap Fund Class I

Fund Overview 

This semi-annual shareholder report contains important information about Mid Cap Fund Class I for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$46	0.93%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$122,138,845
# of Portfolio Holdings	32
Portfolio Turnover Rate	11%
Total Advisory Fees Paid	$598,960

What does the Fund invest in?  

The Fund invests in common stocks, securities convertible into common stocks and related equity securities of midsize companies defined as those companies with market capitalizations of between $500 million and $70 billion.

Top Ten Holdings (% of Net Assets) 

Arch Capital Group Ltd.	7.2%
Amphenol Corp., Class A	5.6%
Brown & Brown, Inc.	5.5%
Gartner, Inc.	5.2%
Ross Stores, Inc.	4.7%
Carlisle Cos., Inc.	4.3%
CDW Corp.	4.2%
Copart, Inc.	3.7%
PACCAR, Inc.	3.6%
Liberty Media Corp.-Liberty Formula One, Class C	3.4%

Sector Allocation (% of Net Assets) 

Information Technology	26.0%
Financials	24.1%
Industrials	16.6%
Consumer Discretionary	14.3%
Health Care	8.0%
Communication Services	6.5%
Short-Term Investments	4.6%
Other Assets and Liabilities, Net	(0.1%)

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089

Mid Cap Fund Class I

  Semi-Annual Shareholder Report June 30, 2025

Mid Cap Fund Class II

Fund Overview 

This semi-annual shareholder report contains important information about Mid Cap Fund Class II for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class II	$59	1.18%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$122,138,845
# of Portfolio Holdings	32
Portfolio Turnover Rate	11%
Total Advisory Fees Paid	$598,960

What does the Fund invest in?  

The Fund invests in common stocks, securities convertible into common stocks and related equity securities of midsize companies defined as those companies with market capitalizations of between $500 million and $70 billion.

Top Ten Holdings (% of Net Assets) 

Arch Capital Group Ltd.	7.2%
Amphenol Corp., Class A	5.6%
Brown & Brown, Inc.	5.5%
Gartner, Inc.	5.2%
Ross Stores, Inc.	4.7%
Carlisle Cos., Inc.	4.3%
CDW Corp.	4.2%
Copart, Inc.	3.7%
PACCAR, Inc.	3.6%
Liberty Media Corp.-Liberty Formula One, Class C	3.4%

Sector Allocation (% of Net Assets) 

Information Technology	26.0%
Financials	24.1%
Industrials	16.6%
Consumer Discretionary	14.3%
Health Care	8.0%
Communication Services	6.5%
Short-Term Investments	4.6%
Other Assets and Liabilities, Net	(0.1%)

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089

Mid Cap Fund Class II

  Semi-Annual Shareholder Report June 30, 2025

Madison Target Retirement 2020 Fund Class I

Fund Overview 

This semi-annual shareholder report contains important information about Madison Target Retirement 2020 Fund Class I for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$16	0.31%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$10,973,144
# of Portfolio Holdings	17
Portfolio Turnover Rate	9%
Total Advisory Fees Paid	$14,342

What does the Fund invest in?  

The Fund primarily invests in shares of other registered investment companies, following an asset allocation strategy for those planning to retire around 2020. As time progresses, the Fund’s allocation will shift to a more conservative mix, aiming for about 10-30% in stock funds and 70-90% in bond funds.

Top Ten Holdings (% of Net Assets) 

Janus Henderson Mortgage-Backed Securities ETF	24.1%
iShares 7-10 Year Treasury Bond ETF	16.8%
Schwab Intermediate-Term U.S. Treasury ETF	16.5%
SPDR Portfolio Short Term Treasury ETF	10.5%
iShares Aaa - A Rated Corporate Bond ETF	7.8%
Invesco S&P 500 Quality ETF	6.2%
iShares MSCI International Quality Factor ETF	3.9%
Distillate U.S. Fundamental Stability & Value ETF	3.3%
Vanguard Information Technology ETF	2.1%
SPDR Portfolio Long Term Treasury ETF	1.6%

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	98.1%
Short-Term Investments	1.9%
Other Assets and Liabilities, Net	0.0%

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089

Madison Target Retirement 2020 Fund Class I

  Semi-Annual Shareholder Report June 30, 2025

Madison Target Retirement 2030 Fund Class I

Fund Overview 

This semi-annual shareholder report contains important information about Madison Target Retirement 2030 Fund Class I for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$16	0.31%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$50,933,863
# of Portfolio Holdings	19
Portfolio Turnover Rate	13%
Total Advisory Fees Paid	$61,385

What does the Fund invest in?  

The Fund primarily invests in shares of other registered investment companies, following an asset allocation strategy for those planning to retire around 2030. As time progresses, the Fund’s allocation will shift to a more conservative mix, aiming for about 10-30% in stock funds and 70-90% in bond funds.

Top Ten Holdings (% of Net Assets) 

Janus Henderson Mortgage-Backed Securities ETF	18.6%
iShares 7-10 Year Treasury Bond ETF	13.2%
Schwab Intermediate-Term U.S. Treasury ETF	11.7%
Invesco S&P 500 Quality ETF	10.3%
Distillate U.S. Fundamental Stability & Value ETF	8.0%
SPDR Portfolio Short Term Treasury ETF	7.9%
iShares Aaa - A Rated Corporate Bond ETF	6.1%
iShares MSCI International Quality Factor ETF	4.6%
Vanguard Information Technology ETF	3.8%
iShares MSCI Emerging Markets Asia ETF	2.4%

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	97.0%
Short-Term Investments	3.0%
Other Assets and Liabilities, Net	0.0%

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089

Madison Target Retirement 2030 Fund Class I

  Semi-Annual Shareholder Report June 30, 2025

Madison Target Retirement 2040 Fund Class I

Fund Overview 

This semi-annual shareholder report contains important information about Madison Target Retirement 2040 Fund Class I for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$16	0.31%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$42,381,174
# of Portfolio Holdings	19
Portfolio Turnover Rate	18%
Total Advisory Fees Paid	$49,619

What does the Fund invest in?  

The Fund primarily invests in shares of other registered investment companies, following an asset allocation strategy for those planning to retire around 2040. As time progresses, the Fund’s allocation will shift to a more conservative mix, aiming for about 10-30% in stock funds and 70-90% in bond funds.

Top Ten Holdings (% of Net Assets) 

Invesco S&P 500 Quality ETF	15.4%
Distillate U.S. Fundamental Stability & Value ETF	12.9%
Janus Henderson Mortgage-Backed Securities ETF	11.0%
Schwab Intermediate-Term U.S. Treasury ETF	9.2%
iShares 7-10 Year Treasury Bond ETF	7.9%
iShares MSCI International Quality Factor ETF	7.0%
Vanguard Information Technology ETF	6.5%
iShares Aaa - A Rated Corporate Bond ETF	4.5%
iShares MSCI Emerging Markets Asia ETF	4.1%
SPDR S&P Bank ETF	3.7%

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	96.5%
Short-Term Investments	3.4%
Other Assets and Liabilities, Net	0.1%

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089

Madison Target Retirement 2040 Fund Class I

  Semi-Annual Shareholder Report June 30, 2025

Madison Target Retirement 2050 Fund Class I

Fund Overview 

This semi-annual shareholder report contains important information about Madison Target Retirement 2050 Fund Class I for the period of January 1, 2025 to June 30, 2025. You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$16	0.31%

¹  Annualized.

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$36,499,161
# of Portfolio Holdings	19
Portfolio Turnover Rate	19%
Total Advisory Fees Paid	$42,692

What does the Fund invest in?  

The Fund primarily invests in shares of other registered investment companies, following an asset allocation strategy for those planning to retire around 2050. As time progresses, the Fund’s allocation will shift to a more conservative mix, aiming for about 10-30% in stock funds and 70-90% in bond funds.

Top Ten Holdings (% of Net Assets) 

Invesco S&P 500 Quality ETF	17.9%
Distillate U.S. Fundamental Stability & Value ETF	15.2%
Janus Henderson Mortgage-Backed Securities ETF	8.0%
iShares MSCI International Quality Factor ETF	7.7%
Vanguard Information Technology ETF	7.2%
Schwab Intermediate-Term U.S. Treasury ETF	6.8%
iShares 7-10 Year Treasury Bond ETF	6.1%
iShares MSCI Emerging Markets Asia ETF	4.9%
iShares MSCI Eurozone ETF	4.2%
SPDR S&P Bank ETF	4.1%

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	96.3%
Short-Term Investments	3.6%
Other Assets and Liabilities, Net	0.1%

Additional Information  If you wish to view additional information about the Fund; including but not limited to financial statements or holdings, please visit www.madisonfunds.com/funds/ultra-series-fund/.   Phone: 1-800-877-6089

Madison Target Retirement 2050 Fund Class I

Item 2. Code of Ethics.

Not applicable in semi-annual report.

Item 3. Audit Committee Financial Expert.

Not applicable in semi-annual report.

Item 4. Principal Accountant Fees and Services.

Not applicable in semi-annual report.

Item 5. Audit Committee of Listed Registrants.

Not applicable in semi-annual report.

Item 6. Schedule of Investments

(a) Schedule of Investments is included as part of the Financial Statement and Financial Highlights for Open-End Management Investment Companies filed under Item 7 of this Form.

(b) Not applicable.

Item 7. Financial Statements and Financial Highlights for Open-End Management Investment Companies.

(a) The registrant’s Financial Statements are attached herewith.

(b) The registrant’s Financial Highlights are attached herewith.

ULTRA SERIES FUND Semi-Annual Financial Statements and Other Information   (unaudited)   June 30, 2025

Conservative Allocation Fund 

Moderate Allocation Fund

Aggressive Allocation Fund

Diversified Income Fund

Core Bond Fund

Large Cap Value Fund

Large Cap Growth Fund

Mid Cap Fund

Madison Target Retirement 2020 Fund

Madison Target Retirement 2030 Fund

Madison Target Retirement 2040 Fund

Madison Target Retirement 2050 Fund

 

Ultra Series Fund | June 30, 2025

Table of Contents

	Page
Portfolios of Investments
Conservative Allocation Fund	3
Moderate Allocation Fund	4
Aggressive Allocation Fund	5
Diversified Income Fund	6
Core Bond Fund	7
Large Cap Value Fund	12
Large Cap Growth Fund	13
Mid Cap Fund	14
Madison Target Retirement 2020 Fund	15
Madison Target Retirement 2030 Fund	16
Madison Target Retirement 2040 Fund	17
Madison Target Retirement 2050 Fund	18
Financial Statements
Statements of Assets and Liabilities	19
Statements of Operations	21
Statements of Changes in Net Assets	23
Financial Highlights for a Share of Beneficial Interest Outstanding	26
Notes to Financial Statements	38

1

Ultra Series Fund | June 30, 2025

Conservative Allocation Fund Portfolio of Investments (unaudited)

	Shares		Value (Note 2,3)
EXCHANGE TRADED FUNDS - 47.9%
Bond Funds - 22.3%
iShares 5-10 Year Investment Grade Corporate Bond ETF		18,064	$	962,631
Janus Henderson Mortgage-Backed Securities ETF		81,863		3,687,928
Schwab Intermediate-Term U.S. Treasury ETF (A)		159,816		4,000,194
SPDR Portfolio Long Term Treasury ETF		31,882		847,424
Vanguard Short-Term Corporate Bond ETF		12,393		985,243
				10,483,420
Foreign Stock Funds - 9.6%
Franklin FTSE Japan ETF		17,507		562,850
iShares MSCI Emerging Markets Asia ETF		15,071		1,244,111
iShares MSCI Eurozone ETF		10,273		610,730
Vanguard FTSE All-World ex-U.S. ETF		10,488		705,003
Vanguard FTSE Europe ETF		17,829		1,381,748
				4,504,442
Stock Funds - 16.0%
Distillate U.S. Fundamental Stability & Value ETF (A)		17,446		965,636
Energy Select Sector SPDR Fund ETF		5,335		452,461
Invesco S&P 500 Quality ETF		43,648		3,110,357
iShares Core S&P Small-Cap ETF		7,107		776,724
SPDR S&P Bank ETF (A)		12,842		716,070
Vanguard Information Technology ETF		2,198		1,457,889
				7,479,137
Total Exchange Traded Funds
(Cost $20,384,570)				22,466,999
INVESTMENT COMPANIES - 50.9%
Bond Funds - 42.4%
Madison Core Bond Fund, Class R6 (B) (C)		2,209,554		19,908,086
Stock Funds - 8.5%
Madison Large Cap Fund, Class R6 (C)		133,304		3,985,781
Total Investment Companies
(Cost $24,058,453)				23,893,867

	Shares		Value (Note 2,3)
SHORT-TERM INVESTMENTS - 2.8%
State Street Institutional U.S. Government Money Market Fund, Premier Class (D), 4.270%		445,182	$	445,182
State Street Navigator Securities Lending Government Money Market Portfolio (D) (E), 4.350%		913,695		913,695
Total Short-Term Investments
(Cost $1,358,877)				1,358,877
TOTAL INVESTMENTS - 101.6%
(Cost $45,801,900**)				47,719,743
NET OTHER ASSETS AND LIABILITIES - (1.6%)				(735,654	)
TOTAL NET ASSETS - 100.0%			$	46,984,089

**	Aggregate cost for Federal tax purposes was $46,188,145.
(A)	All or a portion of these securities, with an aggregate fair value of $1,678,713, are on loan as part of a securities lending program. See footnote (E) and Note 8 for details on the securities lending program.
(B)	Greater than 25% of the portfolio. For more information refer the website https://madisonfunds.com/funds/ultra-series-fund/.
(C)	Affiliated Company (see Note 10).
(D)	7-day yield.
(E)	Represents investments of cash collateral received in connection with securities lending.
ETF	Exchange Traded Fund.
FTSE	The Financial Times Stock Exchange.
MSCI	Morgan Stanley Capital International.
S&P	Standard & Poor’s.
SPDR	Standard & Poor’s Depositary Receipt.

See accompanying Notes to Financial Statements.

3

Ultra Series Fund | June 30, 2025

Moderate Allocation Fund Portfolio of Investments (unaudited)

	Shares		Value (Note 2,3)
EXCHANGE TRADED FUNDS - 54.7%
Bond Funds - 10.9%
iShares 5-10 Year Investment Grade Corporate Bond ETF		34,336	$	1,829,766
Janus Henderson Mortgage-Backed Securities ETF		95,558		4,304,888
Schwab Intermediate-Term U.S. Treasury ETF		124,436		3,114,633
SPDR Portfolio Long Term Treasury ETF		68,892		1,831,149
				11,080,436
Foreign Stock Funds - 17.2%
Franklin FTSE Japan ETF (A)		63,317		2,035,641
iShares MSCI Emerging Markets Asia ETF (A)		58,896		4,861,865
iShares MSCI Eurozone ETF (A)		34,295		2,038,838
Vanguard FTSE All-World ex-U.S. ETF		45,518		3,059,720
Vanguard FTSE Europe ETF		72,134		5,590,385
				17,586,449
Stock Funds - 26.6%
Distillate U.S. Fundamental Stability & Value ETF (A)		66,002		3,653,211
Energy Select Sector SPDR Fund ETF		23,017		1,952,072
Invesco S&P 500 Quality ETF		138,302		9,855,400
iShares Core S&P Small-Cap ETF		30,124		3,292,252
SPDR S&P Bank ETF (A)		55,758		3,109,066
Vanguard Information Technology ETF		7,875		5,223,330
				27,085,331
Total Exchange Traded Funds
(Cost $49,322,032)				55,752,216
INVESTMENT COMPANIES - 42.1%
Bond Funds - 27.2%
Madison Core Bond Fund, Class R6 (B) (C)		3,080,831		27,758,292
Stock Funds - 14.9%
Madison Large Cap Fund, Class R6 (C)		471,426		14,095,634
Madison Mid Cap Fund, Class R6 (C)		64,914		1,105,495
				15,201,129
Total Investment Companies
(Cost $37,700,465)				42,959,421

	Shares		Value (Note 2,3)
SHORT-TERM INVESTMENTS - 6.7%
State Street Institutional U.S. Government Money Market Fund, Premier Class (D), 4.270%		3,247,042	$	3,247,042
State Street Navigator Securities Lending Government Money Market Portfolio (D) (E), 4.350%		3,545,191		3,545,191
Total Short-Term Investments
(Cost $6,792,233)				6,792,233
TOTAL INVESTMENTS - 103.5%
(Cost $93,814,730**)				105,503,870
NET OTHER ASSETS AND LIABILITIES - (3.5%)				(3,544,572	)
TOTAL NET ASSETS - 100.0%			$	101,959,298

**	Aggregate cost for Federal tax purposes was $94,307,698.
(A)	All or a portion of these securities, with an aggregate fair value of $3,824,490, are on loan as part of a securities lending program. See footnote (E) and Note 8 for details on the securities lending program.
(B)	Greater than 25% of the portfolio. For more information refer the website https://madisonfunds.com/funds/ultra-series-fund/.
(C)	Affiliated Company (see Note 10).
(D)	7-day yield.
(E)	Represents investments of cash collateral received in connection with securities lending.
ETF	Exchange Traded Fund.
FTSE	The Financial Times Stock Exchange.
MSCI	Morgan Stanley Capital International.
S&P	Standard & Poor’s.
SPDR	Standard & Poor’s Depositary Receipt.

See accompanying Notes to Financial Statements.

4

Ultra Series Fund | June 30, 2025

Aggressive Allocation Fund Portfolio of Investments (unaudited)

	Shares		Value (Note 2,3)
EXCHANGE TRADED FUNDS - 64.5%
Bond Funds - 3.9%
Janus Henderson Mortgage-Backed Securities ETF		12,523	$	564,161
Schwab Intermediate-Term U.S. Treasury ETF (A)		12,545		314,001
SPDR Portfolio Long Term Treasury ETF		27,376		727,654
				1,605,816
Foreign Stock Funds - 23.2%
Franklin FTSE Japan ETF		35,335		1,136,020
iShares MSCI Emerging Markets Asia ETF (A)		31,358		2,588,603
iShares MSCI Eurozone ETF (A)		17,399		1,034,371
Vanguard FTSE All-World ex-U.S. ETF		21,554		1,448,860
Vanguard FTSE Europe ETF		43,995		3,409,612
				9,617,466
Stock Funds - 37.4%
Distillate U.S. Fundamental Stability & Value ETF (A)		50,636		2,802,703
Energy Select Sector SPDR Fund ETF		11,683		990,835
Invesco S&P 500 Quality ETF		71,787		5,115,542
iShares Core S&P Small-Cap ETF		15,589		1,703,722
SPDR S&P Bank ETF (A)		33,398		1,862,272
Vanguard Information Technology ETF		4,565		3,027,873
				15,502,947
Total Exchange Traded Funds (Cost $23,310,503)				26,726,229
INVESTMENT COMPANIES - 31.8%
Bond Funds - 13.9%
Madison Core Bond Fund, Class R6 (B)		639,873		5,765,260
Stock Funds - 17.9%
Madison Large Cap Fund, Class R6 (B)		229,040		6,848,307
Madison Mid Cap Fund, Class R6 (B)		32,045		545,717
				7,394,024
Total Investment Companies (Cost $10,130,973)				13,159,284

	Shares		Value (Note 2,3)
SHORT-TERM INVESTMENTS - 8.7%
State Street Institutional U.S. Government Money Market Fund, Premier Class (C), 4.270%		1,640,241	$	1,640,241
State Street Navigator Securities Lending Government Money Market Portfolio (C) (D), 4.350%		1,931,648		1,931,648
Total Short-Term Investments (Cost $3,571,889)				3,571,889
TOTAL INVESTMENTS - 105.0% (Cost $37,013,365**)				43,457,402
NET OTHER ASSETS AND LIABILITIES - (5.0%)				(2,073,923	)
TOTAL NET ASSETS - 100.0%			$	41,383,479

**	Aggregate cost for Federal tax purposes was $37,224,966.
(A)	All or a portion of these securities, with an aggregate fair value of $2,075,446, are on loan as part of a securities lending program. See footnote (D) and Note 8 for details on the securities lending program.
(B)	Affiliated Company (see Note 10).
(C)	7-day yield.
(D)	Represents investments of cash collateral received in connection with securities lending.
ETF	Exchange Traded Fund.
FTSE	The Financial Times Stock Exchange.
MSCI	Morgan Stanley Capital International.
S&P	Standard & Poor’s.
SPDR	Standard & Poor’s Depositary Receipt.

See accompanying Notes to Financial Statements.

5

Ultra Series Fund | June 30, 2025

Diversified Income Fund Portfolio of Investments (unaudited)

	Par Value		Value (Note 2,3)
COMMERCIAL MORTGAGE-BACKED SECURITIES - 0.0%
GSAMP Trust, Series 2006-S5, Class Class M5 (A) (B) (C), 7.488%, 9/25/36	$	2,190,000	$	–
Total Commercial Mortgage-Backed Securities (Cost $–)				–
MORTGAGE BACKED SECURITIES - 0.0%
Fannie Mae - 0.0%
7.000%, 11/1/31 Pool # 607515		6,212		6,547
7.000%, 5/1/32 Pool # 644591		793		836
				7,383
Freddie Mac - 0.0%
8.000%, 6/1/30 Pool # C01005		3,014		3,147
Ginnie Mae - 0.0%
6.500%, 4/20/31 Pool # 3068		6,060		6,312
Total Mortgage Backed Securities (Cost $16,087)				16,842
	Shares
EXCHANGE TRADED FUNDS - 99.4%
Bond Funds - 57.2%
iShares 5-10 Year Investment Grade Corporate Bond ETF		54,016	$	2,878,513
Janus Henderson Mortgage-Backed Securities ETF (D)		157,638		7,101,592
Madison Aggregate Bond ETF (D) (E)		1,265,000		25,763,749
Madison Short-Term Strategic Income ETF (D) (E)		1,562,500		32,225,156
SPDR Portfolio High Yield Bond ETF (D)		608,301		14,477,564
				82,446,574
Stock Funds - 42.2%
Global X MLP ETF (D)		115,261	$	5,786,102
Madison Covered Call ETF (E)		1,220,000		22,673,700
Madison Dividend Value ETF (D) (E)		1,235,000		27,396,499
Schwab U.S. Dividend Equity ETF (D)		186,851		4,951,551
				60,807,852
Total Exchange Traded Funds (Cost $140,018,650)				143,254,426

	Shares		Value (Note 2,3)
SHORT-TERM INVESTMENTS - 1.4%
State Street Institutional U.S. Government Money Market Fund, Premier Class (F), 4.270%		916,031	$	916,031
State Street Navigator Securities Lending Government Money Market Portfolio (F) (G), 4.350%		1,088,375		1,088,375
Total Short-Term Investments (Cost $2,004,406)				2,004,406
TOTAL INVESTMENTS - 100.8% (Cost $142,039,143**)				145,275,674
NET OTHER ASSETS AND LIABILITIES - (0.8%)				(1,202,013	)
TOTAL NET ASSETS - 100.0%			$	144,073,661

**	Aggregate cost for Federal tax purposes was $142,039,143.
(A)	Floating rate or variable rate note. Rate shown is as of June 30, 2025.
(B)	Coupon rate may change based on changes of the underlying collateral or prepayments of principal. The coupon rate shown represents the rate at June 30, 2025.
(C)	Defaulted Security. Security was deemed illiquid by Madison. Interest is not being accrued.
(D)	All or a portion of these securities, with an aggregate fair value of $7,115,160, are on loan as part of a securities lending program. See footnote (G) and Note 8 for details on the securities lending program.
(E)	Affiliated Company (see Note 10).
(F)	7-day yield.
(G)	Represents investments of cash collateral received in connection with securities lending.
ETF	Exchange Traded Fund.
SPDR	Standard & Poor’s Depositary Receipt.

See accompanying Notes to Financial Statements.

6

Ultra Series Fund | June 30, 2025

Core Bond Fund Portfolio of Investments (unaudited)

	Par Value		Value (Note 2,3)
ASSET BACKED SECURITIES - 1.2%
Chesapeake Funding II LLC, Series 2023- 1A, Class A1 (A), 5.650%, 5/15/35	$	140,428	$	141,120
Enterprise Fleet Financing LLC, Series 2022-4, Class A2 (A), 5.760%, 10/22/29		72,838		73,129
John Deere Owner Trust, Series 2023-B, Class A3, 5.180%, 3/15/28		211,020		212,140
LAD Auto Receivables Trust, Series 2022-1A, Class A (A), 5.210%, 6/15/27		15,340		15,351
Towd Point Mortgage Trust, Series 2024-CES1, Class A1A (B) (C), 5.848%, 1/25/64		208,332		209,081
Total Asset Backed Securities (Cost $647,844)				650,821
COLLATERALIZED MORTGAGE OBLIGATIONS - 6.5%
Bunker Hill Loan Depositary Trust, Series 2019-2, Class A1 (A) (D), 2.879%, 7/25/49		40,233		39,265
CIM Trust, Series 2021-J2, Class A4 (A) (B) (C), 2.500%, 4/25/51		248,445		222,467
Federal Home Loan Mortgage Corp. REMICS, Series 4066, Class DI, 3.000%, 6/15/27		132,898		2,319
Federal Home Loan Mortgage Corp. REMICS, Series 5451, Class A, 5.000%, 5/25/49		236,018		235,710
Federal National Mortgage Association REMICS, Series 2015-12, Class NI, 3.500%, 3/25/30		309,302		14,784
Federal National Mortgage Association REMICS, Series 2011-31, Class DB, 3.500%, 4/25/31		74,071		72,616
Federal National Mortgage Association REMICS, Series 2011-36, Class QB, 4.000%, 5/25/31		116,572		116,321
Federal National Mortgage Association REMICS, Series 2005-79, Class LT, 5.500%, 9/25/35		127,661		133,148
Federal National Mortgage Association REMICS, Series 2020-44, Class TI, 5.500%, 12/25/35		867,812		125,049
Federal National Mortgage Association REMICS, Series 2024-99, Class EA, 5.500%, 5/25/51		443,737		450,268
Federal National Mortgage Association REMICS, Series 2025-5, Class EA, 5.500%, 10/25/51		227,623		231,011
GCAT Trust, Series 2021-NQM1, Class A1 (A) (B) (C), 0.874%, 1/25/66		119,785		106,905

	Par Value		Value (Note 2,3)
Government National Mortgage Association REMICS, Series 2015-53, Class IL, 3.000%, 9/20/44	$	19,114	$	131
JP Morgan Mortgage Trust, Series 2019-5, Class A3 (A) (B) (C), 4.000%, 11/25/49		11,085		10,460
JP Morgan Mortgage Trust, Series 2019-7, Class A3 (A) (B) (C), 3.459%, 2/25/50		49,433		44,746
JP Morgan Mortgage Trust, Series 2021-1, Class A3 (A) (B) (C), 2.500%, 6/25/51		276,660		225,542
JP Morgan Mortgage Trust, Series 2021-6, Class A4 (A) (B) (C), 2.500%, 10/25/51		403,214		360,829
JP Morgan Wealth Management, Series 2020-ATR1, Class A3 (A) (B) (C), 3.000%, 2/25/50		122,230		106,642
PSMC Trust, Series 2020-2, Class A2 (A) (B) (C), 3.000%, 5/25/50		47,952		42,713
PSMC Trust, Series 2021-1, Class A11 (A) (B) (C), 2.500%, 3/25/51		146,304		130,292
RCKT Mortgage Trust, Series 2021-6, Class A5 (A) (B) (C), 2.500%, 12/25/51		235,340		207,911
Sequoia Mortgage Trust, Series 2013-7, Class A2 (B) (C), 3.000%, 6/25/43		191,692		171,948
Towd Point Mortgage Trust, Series 2024-4, Class A1A (B) (C), 4.435%, 10/27/64		445,652		447,657
Wells Fargo Mortgage-Backed Securities Trust, Series 2019-2, Class A1 (A) (B) (C), 4.000%, 4/25/49		6,186		5,879
Total Collateralized Mortgage Obligations (Cost $3,959,167)				3,504,613
COMMERCIAL MORTGAGE-BACKED SECURITIES - 0.8%
Federal Home Loan Mortgage Corp. Multifamily Structured Pass-Through Certificates, Series KJ17, Class A2, 2.982%, 11/25/25		2,525		2,517
Federal Home Loan Mortgage Corp. Multifamily Structured Pass-Through Certificates, Series K059, Class X1 (B) (C), 0.385%, 9/25/26		10,483,078		23,336
FREMF Mortgage Trust, Series 2020-K106, Class B (A) (B) (C), 3.685%, 3/25/53		150,000		140,595
Government National Mortgage Association, Series 2024-153, Class AB, 4.500%, 3/16/65		248,452		244,686
GSAMP Trust, Series 2006-S5, Class M5 (B) (C) (E), 7.488%, 9/25/36		4,940,000		–
Total Commercial Mortgage-Backed Securities (Cost $409,625)				411,134

See accompanying Notes to Financial Statements.

7

Ultra Series Fund | June 30, 2025

Core Bond Fund Portfolio of Investments (unaudited) - continued

	Par Value		Value (Note 2,3)
CORPORATE NOTES AND BONDS - 25.7%
Communication Services - 0.5%
AT&T, Inc., 2.250%, 2/1/32	$	50,000	$	43,043
SBA Communications Corp., 3.875%, 2/15/27		250,000		245,996
				289,039
Consumer Discretionary - 1.3%
American Airlines, Inc./AAdvantage Loyalty IP Ltd. (A), 5.500%, 4/20/26		66,666		66,515
Lowe’s Cos., Inc., 3.000%, 10/15/50		250,000		155,789
Royal Caribbean Cruises Ltd., 7.500%, 10/15/27		150,000		158,488
Tractor Supply Co., 1.750%, 11/1/30		200,000		173,389
Tractor Supply Co., 5.250%, 5/15/33		150,000		153,150
				707,331
Consumer Staples - 1.2%
Keurig Dr. Pepper, Inc., 3.800%, 5/1/50		200,000		148,144
Lamb Weston Holdings, Inc. (A), 4.875%, 5/15/28		150,000		149,139
Mars, Inc., 5.200%, 3/1/35		200,000		202,269
Performance Food Group, Inc. (A), 5.500%, 10/15/27		150,000		149,687
				649,239
Energy - 3.4%
Devon Energy Corp. (F), 5.200%, 9/15/34		200,000		194,217
Diamondback Energy, Inc., 5.400%, 4/18/34		200,000		200,626
Eastern Gas Transmission & Storage, Inc., 3.000%, 11/15/29		150,000		141,665
Energy Transfer LP, 5.250%, 4/15/29		150,000		153,583
Energy Transfer LP, 6.550%, 12/1/33		200,000		217,034
Kinder Morgan, Inc., 5.550%, 6/1/45		150,000		141,670
MPLX LP, 4.800%, 2/15/29		50,000		50,481
MPLX LP, 2.650%, 8/15/30		200,000		180,992
ONEOK, Inc., 5.850%, 1/15/26		100,000		100,507
Sunoco LP/Sunoco Finance Corp., 6.000%, 4/15/27		150,000		149,960
Valero Energy Corp., 4.000%, 6/1/52		100,000		70,659
Valero Energy Partners LP, 4.500%, 3/15/28		200,000		200,370
				1,801,764
Financials - 11.4%
Aflac, Inc., 4.750%, 1/15/49		250,000		215,739
American Express Co., (Secured Overnight Financing Rate + 1.940%) (B) (C), 6.489%, 10/30/31		250,000		272,315
Athene Holding Ltd., 6.250%, 4/1/54		125,000		123,526
Bank of America Corp., (5 year CMT + 2.000%) (B) (C), 3.846%, 3/8/37		150,000		137,280

	Par Value		Value (Note 2,3)
Capital One Financial Corp., (Secured Overnight Financing Rate + 2.640%) (B) (C), 6.312%, 6/8/29	$	200,000	$	209,913
CBRE Services, Inc., 4.800%, 6/15/30		125,000		125,516
Citibank NA, 5.803%, 9/29/28		250,000		261,366
Citigroup, Inc., (Secured Overnight Financing Rate + 2.086%) (B) (C), 4.910%, 5/24/33		250,000		249,461
Citigroup, Inc., (5 year CMT + 1.730%) (B) (C), 5.411%, 9/19/39		150,000		145,692
Empower Finance 2020 LP (A), 3.075%, 9/17/51		125,000		79,226
Fifth Third Bancorp, (Secured Overnight Financing Rate + 1.660%) (B) (C), 4.337%, 4/25/33		200,000		190,952
GLP Capital LP/GLP Financing II, Inc., 3.250%, 1/15/32		200,000		176,015
Goldman Sachs BDC, Inc., 2.875%, 1/15/26		200,000		197,788
Goldman Sachs Group, Inc., (Secured Overnight Financing Rate + 1.580%) (B) (C), 5.218%, 4/23/31		250,000		256,182
Jefferies Financial Group, Inc., 2.625%, 10/15/31		250,000		217,445
Jefferies Financial Group, Inc., 6.200%, 4/14/34		100,000		104,621
JPMorgan Chase & Co., (Secured Overnight Financing Rate + 1.620%) (B) (C), 5.336%, 1/23/35		250,000		255,921
JPMorgan Chase & Co., (Secured Overnight Financing Rate + 1.680%) (B) (C), 5.572%, 4/22/36		200,000		207,362
KeyCorp, 4.100%, 4/30/28		150,000		149,035
KKR Group Finance Co. VIII LLC (A), 3.500%, 8/25/50		250,000		170,785
Liberty Mutual Group, Inc. (A), 4.569%, 2/1/29		150,000		150,069
Morgan Stanley, (Secured Overnight Financing Rate + 1.020%) (B) (C), 1.928%, 4/28/32		250,000		213,675
Morgan Stanley, (Secured Overnight Financing Rate + 1.730%) (B) (C), 5.466%, 1/18/35		250,000		255,541
Nasdaq, Inc., 1.650%, 1/15/31		200,000		172,400
Old Republic International Corp., 3.850%, 6/11/51		100,000		70,991
Omega Healthcare Investors, Inc., 3.375%, 2/1/31		225,000		205,815
PNC Bank NA, 2.700%, 10/22/29		125,000		116,597
PNC Financial Services Group, Inc., (Secured Overnight Financing Rate + 2.284%) (B) (C), 6.875%, 10/20/34		200,000		223,633
Realty Income Corp., 4.850%, 3/15/30		200,000		203,524

See accompanying Notes to Financial Statements.

8

Ultra Series Fund | June 30, 2025

Core Bond Fund Portfolio of Investments (unaudited) - continued

	Par Value		Value (Note 2,3)
State Street Corp., (Secured Overnight Financing Rate + 1.490%) (B) (C), 3.031%, 11/1/34	$	125,000	$	115,445
Truist Financial Corp., (Secured Overnight Financing Rate + 2.361%) (B) (C), 5.867%, 6/8/34		200,000		208,913
U.S. Bancorp, (Secured Overnight Financing Rate + 1.560%) (B) (C), 5.384%, 1/23/30		125,000		128,672
U.S. Bancorp, (Secured Overnight Financing Rate + 1.600%) (B) (C), 4.839%, 2/1/34		100,000		98,760
Wells Fargo & Co., (Secured Overnight Financing Rate + 2.100%) (B) (C), 2.393%, 6/2/28		100,000		96,374
Wells Fargo & Co., (Secured Overnight Financing Rate + 1.500%) (B) (C), 5.198%, 1/23/30		125,000		128,002
				6,134,551
Health Care - 1.5%
Amgen, Inc., 5.650%, 3/2/53		75,000		73,392
Centene Corp., 2.450%, 7/15/28		150,000		139,278
Cigna Group, 4.375%, 10/15/28		50,000		50,051
Health Care Service Corp. A Mutual Legal Reserve Co. (A), 2.200%, 6/1/30		250,000		223,480
Humana, Inc., 5.375%, 4/15/31		100,000		102,273
J.M. Smucker Co., 6.200%, 11/15/33		200,000		214,520
				802,994
Industrials - 2.8%
Ball Corp., 4.875%, 3/15/26		250,000		249,675
Boeing Co., 6.858%, 5/1/54		200,000		219,232
Carrier Global Corp., 3.577%, 4/5/50		51,000		37,471
Otis Worldwide Corp., 2.565%, 2/15/30		150,000		138,343
Quanta Services, Inc., 2.900%, 10/1/30		250,000		230,410
Textron, Inc., 2.450%, 3/15/31		250,000		221,509
Vulcan Materials Co., 3.500%, 6/1/30		200,000		191,292
WRKCo, Inc., 3.900%, 6/1/28		200,000		197,352
				1,485,284
Information Technology - 2.5%
Broadcom, Inc. (A), 3.187%, 11/15/36		12,000		9,948
Dell International LLC/EMC Corp., 8.350%, 7/15/46		62,000		79,162
Dell International LLC/EMC Corp., 3.450%, 12/15/51		275,000		188,772
Fiserv, Inc., 3.500%, 7/1/29		200,000		192,609
Gartner, Inc. (A), 4.500%, 7/1/28		150,000		148,412
HP, Inc., 2.650%, 6/17/31		200,000		176,753
Iron Mountain, Inc. (A), 4.500%, 2/15/31		125,000		119,139

	Par Value		Value (Note 2,3)
Oracle Corp., 3.950%, 3/25/51	$	250,000	$	184,678
VMware LLC, 2.200%, 8/15/31		250,000		216,841
				1,316,314
Materials - 0.5%
Celanese U.S. Holdings LLC, 6.415%, 7/15/27		96,000		99,396
LYB International Finance III LLC, 3.625%, 4/1/51		250,000		167,456
				266,852
Utilities - 0.6%
Duke Energy Corp., 3.750%, 9/1/46		250,000		185,320
Interstate Power & Light Co., 3.500%, 9/30/49		225,000		158,512
				343,832
Total Corporate Notes and Bonds (Cost $14,729,004)				13,797,200
FOREIGN CORPORATE BONDS - 3.1%
Energy - 0.2%
Enbridge, Inc., 5.700%, 3/8/33		125,000		129,596
Financials - 2.2%
AerCap Ireland Capital DAC/AerCap Global Aviation Trust, 1.750%, 1/30/26		150,000		147,373
AerCap Ireland Capital DAC/AerCap Global Aviation Trust, 4.625%, 10/15/27		200,000		200,832
Avolon Holdings Funding Ltd. (A), 2.125%, 2/21/26		121,000		118,762
Mitsubishi UFJ Financial Group, Inc., (1 year CMT + 1.530%) (B) (C), 5.475%, 2/22/31		250,000		259,085
Toronto-Dominion Bank, 4.456%, 6/8/32		250,000		245,399
UBS Group AG, (1 year CMT + 2.050%) (A) (B) (C), 4.703%, 8/5/27		200,000		200,383
				1,171,834
Health Care - 0.6%
Pfizer Investment Enterprises Pte. Ltd., 5.340%, 5/19/63		200,000		185,834
STERIS Irish FinCo UnLtd Co., 3.750%, 3/15/51		200,000		142,602
				328,436
Industrials - 0.1%
BAE Systems PLC (A), 5.300%, 3/26/34		50,000		51,120
Total Foreign Corporate Bonds (Cost $1,739,297)				1,680,986

See accompanying Notes to Financial Statements.

9

Ultra Series Fund | June 30, 2025

Core Bond Fund Portfolio of Investments (unaudited) - continued

	Par Value		Value (Note 2,3)
MORTGAGE BACKED SECURITIES - 41.1%
Fannie Mae - 25.7%
3.000%, 9/1/30 Pool # 890696	$	194,061	$	189,690
3.000%, 12/1/30 Pool # AL8924		68,657		67,368
7.000%, 11/1/31 Pool # 607515		6,212		6,547
3.500%, 12/1/31 Pool # MA0919		24,224		23,763
6.500%, 3/1/32 Pool # 631377		8,418		8,692
7.000%, 5/1/32 Pool # 644591		1,442		1,520
6.500%, 6/1/32 Pool # 545691		55,502		57,625
3.500%, 8/1/32 Pool # MA3098		27,730		27,288
5.500%, 11/1/33 Pool # 555880		84,141		86,109
4.000%, 2/1/35 Pool # MA2177		308,903		305,922
3.500%, 12/1/35 Pool # MA2473		175,829		170,547
4.000%, 6/1/36 Pool # AL8618		83,079		81,589
2.500%, 9/1/36 Pool # FS4049		344,053		323,503
5.500%, 10/1/36 Pool # 901723		45,890		46,788
6.500%, 10/1/36 Pool # 894118		50,893		52,550
6.000%, 11/1/36 Pool # 902510		153,638		160,633
6.000%, 10/1/37 Pool # 947563		146,434		153,569
4.500%, 5/1/38 Pool # MA5013		176,199		175,183
6.500%, 8/1/38 Pool # 987711		219,551		231,984
3.000%, 11/1/39 Pool # MA3831		40,983		38,365
2.500%, 8/1/40 Pool # BP6565		541,195		491,089
4.000%, 1/1/41 Pool # AB2080		331,279		320,024
2.500%, 5/1/41 Pool # MA4334		342,072		305,500
4.500%, 7/1/41 Pool # AB3274		144,799		143,816
5.500%, 7/1/41 Pool # AL6588		293,684		302,998
4.000%, 9/1/41 Pool # AJ1406		147,575		142,561
2.500%, 3/1/42 Pool # CB3076		383,561		339,102
3.500%, 6/1/42 Pool # AO4136		361,185		339,111
4.000%, 6/1/42 Pool # MA1087		97,744		94,210
3.500%, 8/1/42 Pool # AP2133		170,329		159,937
3.500%, 9/1/42 Pool # AB6228		293,822		275,743
4.000%, 10/1/42 Pool # AP7363		241,277		232,453
3.500%, 3/1/43 Pool # AT0310		202,156		189,802
5.000%, 11/1/44 Pool # MA5539		226,675		226,618
4.000%, 1/1/45 Pool # AS4257		45,743		43,485
4.500%, 2/1/45 Pool # MA2193		78,278		76,505
3.500%, 11/1/45 Pool # BA4907		117,747		109,330
3.500%, 12/1/45 Pool # AS6309		91,820		85,295
4.500%, 10/1/46 Pool # MA2783		18,282		17,838
4.000%, 12/1/46 Pool # BD2379		58,537		55,454
3.000%, 1/1/47 Pool # BE0108		194,500		173,772
2.500%, 12/1/47 Pool # FM3165		389,991		333,750
3.000%, 1/1/48 Pool # FM1303		473,434		423,007
4.000%, 7/1/48 Pool # MA3415		90,177		85,339
3.000%, 1/1/49 Pool # FS4296		281,889		254,461
4.000%, 11/1/50 Pool # FM5530		249,399		233,566

	Par Value		Value (Note 2,3)
2.000%, 12/1/51 Pool # FM9925	$	614,723	$	495,087
2.000%, 1/1/52 Pool # CB2601		317,740		256,108
2.500%, 3/1/52 Pool # BV4133		241,397		200,344
2.500%, 4/1/52 Pool # FS4138		209,532		175,668
4.000%, 5/1/52 Pool # FS1704		1,014,979		946,477
3.500%, 6/1/52 Pool # CB3845		607,886		549,695
4.500%, 8/1/52 Pool # FS2605		1,064,939		1,022,660
4.000%, 9/1/52 Pool # MA4732		209,083		194,791
5.000%, 10/1/52 Pool # MA4785		387,667		381,814
5.500%, 10/1/52 Pool # MA4786		254,968		255,698
5.000%, 11/1/52 Pool # MA4806		301,826		297,814
5.000%, 12/1/52 Pool # MA4841		206,076		203,190
5.500%, 12/1/52 Pool # MA4842		79,399		79,632
4.500%, 7/1/53 Pool # FS4996		184,041		176,576
5.500%, 7/1/53 Pool # MA5072		209,213		209,505
5.500%, 9/1/53 Pool # FS5575		297,061		299,396
5.500%, 5/1/54 Pool # FS7759		398,867		399,951
				13,808,407
Freddie Mac - 15.4%
8.000%, 6/1/30 Pool # C01005		3,768		3,933
7.000%, 3/1/31 Pool # C48129		15,431		16,279
2.500%, 2/1/32 Pool # ZS8641		64,609		62,027
5.500%, 11/1/34 Pool # A28282		76,613		78,176
2.500%, 6/1/35 Pool # RC1421		129,408		121,261
5.500%, 1/1/37 Pool # G04593	$	55,860	$	57,722
5.000%, 5/1/40 Pool # SB8384		342,741		345,163
2.000%, 3/1/41 Pool # RB5105		330,347		284,512
4.000%, 10/1/41 Pool # Q04092		165,185		159,614
3.000%, 9/1/42 Pool # C04233		476,205		431,322
3.500%, 8/1/44 Pool # Q27927		174,794		162,865
3.000%, 7/1/45 Pool # G08653		203,820		181,699
3.500%, 8/1/45 Pool # Q35614		260,398		242,358
3.000%, 10/1/46 Pool # G60722		307,724		274,418
4.000%, 3/1/47 Pool # Q46801		78,713		74,662
3.500%, 12/1/47 Pool # Q52955		112,388		103,121
2.500%, 4/1/48 Pool # QA2240		309,818		264,936
3.000%, 7/1/49 Pool # QA1033		161,176		141,045
2.500%, 1/1/52 Pool # SD7552		939,936		791,383
3.500%, 4/1/52 Pool # SD0960		588,942		539,311
3.500%, 5/1/52 Pool # RA7380		356,053		321,442
3.000%, 8/1/52 Pool # SD7556		555,785		486,290
4.500%, 11/1/52 Pool # SD8266		422,754		405,087
5.000%, 11/1/52 Pool # SD8267		165,277		162,773
5.500%, 11/1/52 Pool # SD1859		198,612		200,281
4.500%, 12/1/52 Pool # SD1921		284,948		274,642
5.000%, 12/1/52 Pool # SD8276		209,170		206,001

See accompanying Notes to Financial Statements.

10

Ultra Series Fund | June 30, 2025

Core Bond Fund Portfolio of Investments (unaudited) - concluded

	Par Value		Value (Note 2,3)
5.000%, 1/1/53 Pool # SD8288	$	180,485	$	177,741
5.000%, 2/1/53 Pool # SD8299		471,752		464,303
5.500%, 2/1/53 Pool # SD2172		249,712		252,036
5.000%, 5/1/53 Pool # SD2875		335,931		333,077
6.000%, 9/1/53 Pool # SD3739		582,456		595,849
5.500%, 2/1/54 Pool # SD4901		88,464		88,786
				8,304,115
Ginnie Mae - 0.0%
6.500%, 2/20/29 Pool # 2714		7,094		7,292
6.500%, 4/20/31 Pool # 3068		7,358		7,665
				14,957
Total Mortgage Backed Securities (Cost $23,080,123)				22,127,479
U.S. GOVERNMENT AND AGENCY OBLIGATIONS - 18.9%
U.S. Treasury Bonds - 10.9%
6.625%, 2/15/27		750,000		785,684
4.500%, 5/15/38		750,000		759,199
3.750%, 8/15/41		750,000		672,451
4.625%, 5/15/44		565,000		554,737
3.000%, 5/15/45		750,000		575,244
2.500%, 5/15/46		500,000		345,840
3.375%, 11/15/48		500,000		396,074
1.250%, 5/15/50		750,000		360,908
1.875%, 2/15/51		500,000		281,406
4.125%, 8/15/53		500,000		447,344
4.250%, 8/15/54		750,000		685,957
				5,864,844
U.S. Treasury Notes - 8.0%
4.625%, 6/15/27		300,000		304,957
2.875%, 5/15/28		750,000		733,154
2.625%, 2/15/29		750,000		722,168
3.875%, 11/30/29		500,000		502,129
4.000%, 7/31/30		350,000		352,994
4.250%, 6/30/31		175,000		178,213
4.000%, 2/15/34		750,000		742,295
4.375%, 5/15/34		750,000		761,807
				4,297,717
Total U.S. Government and Agency Obligations (Cost $11,037,972)				10,162,561

	Par Value		Value (Note 2,3)
SHORT-TERM INVESTMENTS - 2.5%
State Street Institutional U.S. Government Money Market Fund, Premier Class (G), 4.270%	$	1,102,974	$	1,102,974
State Street Navigator Securities Lending Government Money Market Portfolio (G) (H), 4.350%		196,490		196,490
Total Short-Term Investments (Cost $1,299,464)				1,299,464
TOTAL INVESTMENTS - 99.8% (Cost $56,902,496**)				53,634,258
NET OTHER ASSETS AND LIABILITIES - 0.2%				120,673
TOTAL NET ASSETS - 100.0%			$	53,754,931

**	Aggregate cost for Federal tax purposes was $56,968,361.
(A)	Security sold within terms of a private placement memorandum exempt from registration under section 144A of the Securities Act of 1933, as amended, and may be sold only to dealers in that program or other qualified institutional buyers.”
(B)	Floating rate or variable rate note. Rate shown is as of June 30, 2025.
(C)	Coupon rate may change based on changes of the underlying collateral or prepayments of principal. The coupon rate shown represents the rate at June 30, 2025.
(D)	Stepped rate security. Rate shown is as of June 30, 2025.
(E)	Defaulted Security. Security was deemed illiquid by Madison. Interest is not being accrued.
(F)	All or a portion of these securities, with an aggregate fair value of $193,305, are on loan as part of a securities lending program. See footnote (H) and Note 8 for details on the securities lending program.
(G)	7-day yield.
(H)	Represents investments of cash collateral received in connection with securities lending.
BDC	Business Development Company.
CMT	Constant Maturity Treasury.
DAC	Designated Activity Company.
FREMF	Freddie Mac Multifamily Securities.
IO	Interest Only.
LLC	Limited Liability Corporation.
LP	Limited Partnership.
PLC	Public Limited Company.
REMIC	Real Estate Mortgage Investment Conduit.

See accompanying Notes to Financial Statements.

11

Ultra Series Fund | June 30, 2025

Large Cap Value Fund Portfolio of Investments (unaudited)

	Shares		Value (Note 2,3)
COMMON STOCKS - 98.4%
Communication Services - 2.7%
Comcast Corp., Class A		126,193	$	4,503,828
Consumer Discretionary - 8.7%
Home Depot, Inc.		15,870		5,818,577
Lowe’s Cos., Inc.		19,185		4,256,576
McDonald’s Corp.		7,500		2,191,275
Starbucks Corp.		22,259		2,039,592
				14,306,020
Consumer Staples - 7.3%
Colgate-Palmolive Co.		33,207		3,018,516
Hershey Co.		15,164		2,516,466
PepsiCo, Inc.		24,139		3,187,314
Procter & Gamble Co.		21,175		3,373,601
				12,095,897
Energy - 8.9%
Chevron Corp.		29,233		4,185,873
ConocoPhillips		26,702		2,396,238
EOG Resources, Inc.		40,674		4,865,017
Exxon Mobil Corp.		29,798		3,212,224
				14,659,352
Equity Real Estate Investment Trusts (REITs) - 2.8%
American Tower Corp., REIT		20,993		4,639,873
Financials - 20.0%
Bank of America Corp.		95,009		4,495,826
Blackrock, Inc.		6,148		6,450,789
CME Group, Inc.		25,498		7,027,759
JPMorgan Chase & Co.		17,774		5,152,860
Marsh & McLennan Cos., Inc.		15,877		3,471,347
Morgan Stanley		44,956		6,332,502
				32,931,083
Health Care - 14.1%
Abbott Laboratories		32,227		4,383,194
AbbVie, Inc.		23,243		4,314,366
Elevance Health, Inc.		10,465		4,070,467
Johnson & Johnson		35,947		5,490,904
Medtronic PLC		57,483		5,010,793
				23,269,724
Industrials - 20.3%
Automatic Data Processing, Inc.		21,200		6,538,080
Caterpillar, Inc.		4,388		1,703,465
Cummins, Inc.		7,003		2,293,482
Fastenal Co.		130,213		5,468,946
Honeywell International, Inc.		27,069		6,303,829
Paychex, Inc.		20,934		3,045,060
Rockwell Automation, Inc.		8,652		2,873,935

	Shares		Value (Note 2,3)
Union Pacific Corp.		23,010	$	5,294,141
				33,520,938
Information Technology - 8.1%
Accenture PLC, Class A		4,680		1,398,805
Analog Devices, Inc.		9,693		2,307,128
TE Connectivity PLC		22,400		3,778,208
Texas Instruments, Inc.		27,919		5,796,543
				13,280,684
Materials - 1.9%
Air Products & Chemicals, Inc.		11,334		3,196,868
Utilities - 3.6%
NextEra Energy, Inc.		84,272		5,850,162
Total Common Stocks (Cost $124,652,435)				162,254,429
SHORT-TERM INVESTMENTS - 1.6%
State Street Institutional U.S. Government Money Market Fund, Premier Class (A), 4.270%		2,613,412		2,613,412
Total Short-Term Investments (Cost $2,613,412)				2,613,412
TOTAL INVESTMENTS - 100.0% (Cost $127,265,847**)				164,867,841
NET OTHER ASSETS AND LIABILITIES - 0.0%				(70,833	)
TOTAL NET ASSETS - 100.0%			$	164,797,008

**	Aggregate cost for Federal tax purposes was $127,299,033.
(A)	7-day yield.
PLC	Public Limited Company.
REIT	Real Estate Investment Trust.

See accompanying Notes to Financial Statements.

12

Ultra Series Fund | June 30, 2025

Large Cap Growth Fund Portfolio of Investments (unaudited)

	Shares		Value (Note 2,3)
COMMON STOCKS - 98.0%
Communication Services - 7.1%
Alphabet, Inc., Class C		52,790	$	9,364,418
Liberty Broadband Corp., Class C*		35,255		3,468,387
				12,832,805
Consumer Discretionary - 15.5%
Airbnb, Inc., Class A*		22,600		2,990,884
Amazon.com, Inc.*		43,300		9,499,587
Lowe’s Cos., Inc.		27,202		6,035,308
NIKE, Inc., Class B		33,410		2,373,446
Starbucks Corp.		37,193		3,407,995
TJX Cos., Inc.		29,690		3,666,418
				27,973,638
Financials -26.1%
Capital Markets - 5.7%
Brookfield Corp.		91,643		5,668,120
Charles Schwab Corp.		51,182		4,669,846
				10,337,966
Financial Services - 8.1%
Fiserv, Inc.*		43,725		7,538,627
Visa, Inc., Class A		19,661		6,980,638
				14,519,265
Insurance - 12.3%
Arch Capital Group Ltd.		118,293		10,770,578
Marsh & McLennan Cos., Inc.		20,755		4,537,873
Progressive Corp.		25,989		6,935,424
				22,243,875
				47,101,106
Health Care - 11.7%
Agilent Technologies, Inc.		39,894		4,707,891
Alcon AG (A)		70,996		6,267,527
Danaher Corp.		33,377		6,593,292
Elevance Health, Inc.		9,433		3,669,060
				21,237,770
Industrials - 17.6%
Copart, Inc.*		107,016		5,251,275
Deere & Co.		9,068		4,610,987
Ferguson Enterprises, Inc.		38,278		8,335,035
PACCAR, Inc.		72,879		6,927,878
Parker-Hannifin Corp.		9,632		6,727,663
				31,852,838

	Shares		Value (Note 2,3)
Information Technology - 20.0%
Accenture PLC, Class A		15,835	$	4,732,923
Analog Devices, Inc.		21,901		5,212,876
CDW Corp.		29,562		5,279,477
Gartner, Inc.*		13,508		5,460,204
Keysight Technologies, Inc.*		39,160		6,416,758
Texas Instruments, Inc.		43,274		8,984,548
				36,086,786
Total Common Stocks (Cost $99,766,211)				177,084,943
SHORT-TERM INVESTMENTS - 2.0%
State Street Institutional U.S. Government Money Market Fund, Premier Class (B), 4.270%		3,704,865		3,704,865
Total Short-Term Investments (Cost $3,704,865)				3,704,865
TOTAL INVESTMENTS - 100.0% (Cost $103,471,076**)				180,789,808
NET OTHER ASSETS AND LIABILITIES - 0.0%				(29,474	)
TOTAL NET ASSETS - 100.0%			$	180,760,334

*	Non-income producing.
**	Aggregate cost for Federal tax purposes was $103,542,545.
(A)	All or a portion of these securities, with an aggregate fair value of $5,339,463, are on loan as part of a securities lending program. See Note 8 for details on the securities lending program.
(B)	7-day yield.
PLC	Public Limited Company.

See accompanying Notes to Financial Statements.

13

Ultra Series Fund | June 30, 2025

Mid Cap Fund Portfolio of Investments (unaudited)

	Shares		Value (Note 2,3)
COMMON STOCKS - 95.5%
Communication Services - 6.5%
Liberty Broadband Corp., Class C*		38,806	$	3,817,734
Liberty Media Corp.-Liberty Formula One, Class C*		39,488		4,126,496
				7,944,230
Consumer Discretionary - 14.3%
Asbury Automotive Group, Inc.*		10,756		2,565,736
Floor & Decor Holdings, Inc., Class A*		47,626		3,617,671
Lithia Motors, Inc.		8,122		2,743,774
Ross Stores, Inc.		45,359		5,786,901
Thor Industries, Inc.		31,549		2,801,867
				17,515,949
Financials - 24.1%
Arch Capital Group Ltd.		96,739		8,808,086
Brookfield Asset Management Ltd., Class A (A)		54,294		3,001,372
Brown & Brown, Inc.		60,623		6,721,272
Cullen/Frost Bankers, Inc.		10,821		1,390,932
Glacier Bancorp, Inc.		29,554		1,273,186
Kinsale Capital Group, Inc.		4,655		2,252,555
Moelis & Co., Class A		34,763		2,166,430
W.R. Berkley Corp.		51,709		3,799,060
				29,412,893
Health Care - 8.0%
Labcorp Holdings, Inc.		15,707		4,123,244
Medpace Holdings, Inc.*		8,300		2,605,038
Waters Corp.*		8,822		3,079,231
				9,807,513
Industrials - 16.6%
Carlisle Cos., Inc.		14,202		5,303,027
Copart, Inc.*		92,613		4,544,520
Expeditors International of Washington, Inc.		15,251		1,742,427
Graco, Inc.		14,212		1,221,805
PACCAR, Inc.		46,762		4,445,196
Trex Co., Inc.*		54,357		2,955,934
				20,212,909

	Shares		Value (Note 2,3)
Information Technology -26.0%
Communications Equipment - 2.8%
Arista Networks, Inc.*		33,122	$	3,388,712
Electronic Equipment, Instruments & Components - 12.5%
Amphenol Corp., Class A		69,343		6,847,621
CDW Corp.		28,751		5,134,641
Teledyne Technologies, Inc.*		6,360		3,258,292
				15,240,554
IT Services - 5.2%
Gartner, Inc.*		15,680		6,338,170
Semiconductors & Semiconductor Equipment - 5.5%
Microchip Technology, Inc.		41,528		2,922,325
MKS, Inc.		38,798		3,854,969
				6,777,294
				31,744,730
Total Common Stocks
(Cost $56,769,933)				116,638,224
SHORT-TERM INVESTMENTS - 4.6%
State Street Institutional U.S. Government Money Market Fund, Premier Class (B), 4.270%		5,611,413		5,611,413
Total Short-Term Investments
(Cost $5,611,413)				5,611,413
TOTAL INVESTMENTS - 100.1% (Cost $62,381,346**)				122,249,637
NET OTHER ASSETS AND LIABILITIES - (0.1%)				(110,792	)
TOTAL NET ASSETS - 100.0%			$	122,138,845

*	Non-income producing.
**	Aggregate cost for Federal tax purposes was $62,622,093.
(A)	All or a portion of these securities, with an aggregate fair value of $2,932,825, are on loan as part of a securities lending program. See Note 8 for details on the securities lending program.
(B)	7-day yield.

See accompanying Notes to Financial Statements.

14

Ultra Series Fund | June 30, 2025

Target Retirement 2020 Fund Portfolio of Investments (unaudited)

	Shares		Value (Note 2,3)
EXCHANGE TRADED FUNDS - 98.1%
Bond Funds - 78.2%
iShares 7-10 Year Treasury Bond ETF		19,290	$	1,847,403
iShares Aaa - A Rated Corporate Bond ETF		17,882		855,475
Janus Henderson AAA CLO ETF		2,200		111,650
Janus Henderson Mortgage-Backed Securities ETF		58,586		2,639,299
Schwab Intermediate-Term U.S. Treasury ETF		72,123		1,805,239
SPDR Portfolio Long Term Treasury ETF		6,404		170,218
SPDR Portfolio Short Term Treasury ETF		39,250		1,149,633
				8,578,917
Foreign Stock Funds - 5.8%
iShares MSCI Emerging Markets Asia ETF		1,676		138,354
iShares MSCI Eurozone ETF		1,328		78,950
iShares MSCI International Quality Factor ETF		9,801		423,599
				640,903
Stock Funds - 14.1%
Distillate Small/Mid Cash Flow ETF		1,713		55,707
Distillate U.S. Fundamental Stability & Value ETF		6,477		358,502
Invesco S&P 500 Quality ETF		9,569		681,887
SPDR Portfolio S&P 400 Mid Cap ETF		1,892		102,887
SPDR S&P Bank ETF		2,190		122,114
Vanguard Information Technology ETF		344		228,168
				1,549,265
Total Exchange Traded Funds (Cost $10,256,615)				10,769,085

	Shares		Value (Note 2,3)
SHORT-TERM INVESTMENTS - 1.9%
State Street Institutional U.S. Government Money Market Fund, Premier Class (A), 4.270%		203,057	$	203,057
Total Short-Term Investments (Cost $203,057)				203,057
TOTAL INVESTMENTS - 100.0%  (Cost $10,459,672**)				10,972,142
NET OTHER ASSETS AND LIABILITIES - 0.0%				1,002
TOTAL NET ASSETS - 100.0%			$	10,973,144

**	Aggregate cost for Federal tax purposes was $10,527,982.
(A)	7-day yield.
CLO	Collateralized Loan Obligation
ETF	Exchange Traded Fund.
MSCI	Morgan Stanley Capital International.
S&P	Standard & Poor’s.
SPDR	Standard & Poor’s Depositary Receipt.

See accompanying Notes to Financial Statements.

15

Ultra Series Fund | June 30, 2025

Target Retirement 2030 Fund Portfolio of Investments (unaudited)

	Shares		Value (Note 2,3)
EXCHANGE TRADED FUNDS - 97.0%
Bond Funds - 60.4%
iShares 7-10 Year Treasury Bond ETF		69,968	$	6,700,835
iShares Aaa - A Rated Corporate Bond ETF		64,942		3,106,825
Janus Henderson AAA CLO ETF		14,650		743,488
Janus Henderson Mortgage-Backed Securities ETF		210,446		9,480,592
Schwab Intermediate-Term U.S. Treasury ETF		238,565		5,971,282
SPDR Portfolio Long Term Treasury ETF		27,368		727,442
SPDR Portfolio Short Term Treasury ETF		137,509		4,027,639
				30,758,103
Foreign Stock Funds - 10.1%
iShares MSCI Emerging Markets Asia ETF		14,976		1,236,269
iShares MSCI Eurozone ETF		17,921		1,065,403
iShares MSCI International Quality Factor ETF		54,107		2,338,504
JPMorgan BetaBuilders Japan ETF		8,179		505,299
				5,145,475
Stock Funds - 26.5%
Distillate Small/Mid Cash Flow ETF		13,756		447,345
Distillate U.S. Fundamental Stability & Value ETF		73,181		4,050,568
Energy Select Sector SPDR Fund ETF		2,308		195,742
Invesco S&P 500 Quality ETF		73,681		5,250,508
SPDR Portfolio S&P 400 Mid Cap ETF		9,131		496,544
SPDR S&P Bank ETF		20,423		1,138,787
Vanguard Information Technology ETF		2,905		1,926,828
				13,506,322
Total Exchange Traded Funds (Cost $45,273,134)				49,409,900

	Shares		Value (Note 2,3)
SHORT-TERM INVESTMENTS - 3.0%
State Street Institutional U.S. Government Money Market Fund, Premier Class (A), 4.270%		1,509,455	$	1,509,455
Total Short-Term Investments (Cost $1,509,455)				1,509,455
TOTAL INVESTMENTS - 100.0% (Cost $46,782,589**)				50,919,355
NET OTHER ASSETS AND LIABILITIES - 0.0%				14,508
TOTAL NET ASSETS - 100.0%			$	50,933,863

**	Aggregate cost for Federal tax purposes was $47,296,170.
(A)	7-day yield.
CLO	Collateralized Loan Obligation
ETF	Exchange Traded Fund.
MSCI	Morgan Stanley Capital International.
S&P	Standard & Poor’s.
SPDR	Standard & Poor’s Depositary Receipt.

See accompanying Notes to Financial Statements.

16

Ultra Series Fund | June 30, 2025

Target Retirement 2040 Fund Portfolio of Investments (unaudited)

	Shares		Value (Note 2,3)
EXCHANGE TRADED FUNDS - 96.5%
Bond Funds - 38.0%
iShares 7-10 Year Treasury Bond ETF		34,983	$	3,350,322
iShares Aaa - A Rated Corporate Bond ETF		39,872		1,907,476
Janus Henderson AAA CLO ETF		12,002		609,102
Janus Henderson Mortgage-Backed Securities ETF		103,807		4,676,505
Schwab Intermediate-Term U.S. Treasury ETF		156,562		3,918,747
SPDR Portfolio Long Term Treasury ETF		15,824		420,602
SPDR Portfolio Short Term Treasury ETF		42,468		1,243,888
				16,126,642
Foreign Stock Funds - 16.1%
iShares MSCI Emerging Markets Asia ETF		20,995		1,733,137
iShares MSCI Eurozone ETF		24,067		1,430,783
iShares MSCI International Quality Factor ETF		68,526		2,961,694
JPMorgan BetaBuilders Japan ETF		11,231		693,851
				6,819,465
Stock Funds - 42.4%
Distillate Small/Mid Cash Flow ETF		12,522		407,216
Distillate U.S. Fundamental Stability & Value ETF		98,548		5,454,632
Energy Select Sector SPDR Fund ETF		2,919		247,560
Invesco S&P 500 Quality ETF		91,755		6,538,461
SPDR Portfolio S&P 400 Mid Cap ETF		17,863		971,390
SPDR S&P Bank ETF		28,329		1,579,625
Vanguard Information Technology ETF		4,162		2,760,571
				17,959,455
Total Exchange Traded Funds (Cost $36,529,816)				40,905,562

	Shares		Value (Note 2,3)
SHORT-TERM INVESTMENTS - 3.4%
State Street Institutional U.S. Government Money Market Fund, Premier Class (A), 4.270%		1,450,601	$	1,450,601
Total Short-Term Investments (Cost $1,450,601)				1,450,601
TOTAL INVESTMENTS - 99.9% (Cost $37,980,417**)				42,356,163
NET OTHER ASSETS AND LIABILITIES - 0.1%				25,011
TOTAL NET ASSETS - 100.0%			$	42,381,174

**	Aggregate cost for Federal tax purposes was $38,277,939.
(A)	7-day yield.
CLO	Collateralized Loan Obligation
ETF	Exchange Traded Fund.
MSCI	Morgan Stanley Capital International.
S&P	Standard & Poor’s.
SPDR	Standard & Poor’s Depositary Receipt.

See accompanying Notes to Financial Statements.

17

Ultra Series Fund | June 30, 2025

Target Retirement 2050 Fund Portfolio of Investments (unaudited)

	Shares		Value (Note 2,3)
EXCHANGE TRADED FUNDS - 96.3%
Bond Funds - 28.2%
iShares 7-10 Year Treasury Bond ETF		23,186	$	2,220,523
iShares Aaa - A Rated Corporate Bond ETF		24,399		1,167,248
Janus Henderson AAA CLO ETF		12,094		613,771
Janus Henderson Mortgage-Backed Securities ETF		64,968		2,926,808
Schwab Intermediate-Term U.S. Treasury ETF		99,764		2,497,093
SPDR Portfolio Long Term Treasury ETF		12,340		327,997
SPDR Portfolio Short Term Treasury ETF		18,552		543,388
				10,296,828
Foreign Stock Funds - 18.8%
iShares MSCI Emerging Markets Asia ETF		21,603		1,783,328
iShares MSCI Eurozone ETF		26,033		1,547,662
iShares MSCI International Quality Factor ETF		65,288		2,821,747
JPMorgan BetaBuilders Japan ETF		11,715		723,753
				6,876,490
Stock Funds - 49.3%
Distillate Small/Mid Cash Flow ETF		15,682		509,979
Distillate U.S. Fundamental Stability & Value ETF		100,329		5,553,210
Energy Select Sector SPDR Fund ETF		2,923		247,900
Invesco S&P 500 Quality ETF		91,488		6,519,435
SPDR Portfolio S&P 400 Mid Cap ETF		19,638		1,067,914
SPDR S&P Bank ETF		26,654		1,486,227
Vanguard Information Technology ETF		3,936		2,610,670
				17,995,335
Total Exchange Traded Funds (Cost $30,695,835)				35,168,653

	Shares		Value (Note 2,3)
SHORT-TERM INVESTMENTS - 3.6%
State Street Institutional U.S. Government Money Market Fund, Premier Class (A), 4.270%		1,310,984	$	1,310,984
Total Short-Term Investments (Cost $1,310,984)				1,310,984
TOTAL INVESTMENTS - 99.9% (Cost $32,006,819**)				36,479,637
NET OTHER ASSETS AND LIABILITIES - 0.1%				19,524
TOTAL NET ASSETS - 100.0%			$	36,499,161

**	Aggregate cost for Federal tax purposes was $32,317,278.
(A)	7-day yield.
CLO	Collateralized Loan Obligation
ETF	Exchange Traded Fund.
MSCI	Morgan Stanley Capital International.
S&P	Standard & Poor’s.
SPDR	Standard & Poor’s Depositary Receipt.

See accompanying Notes to Financial Statements.

18

Ultra Series Fund | June 30, 2025

Statements of Assets and Liabilities as of June 30, 2025 (unaudited)

	Conservative Allocation Fund			Moderate Allocation Fund		Aggressive Allocation Fund		Diversified Income Fund		Core Bond Fund			Large Cap Value Fund		Large Cap Growth Fund
Assets:
Investments in unaffiliated securities, at fair value†§	$	23,825,876		$	62,544,449	$	30,298,118	$	37,216,570	$	53,634,258		$	164,867,841	$	180,789,808
Investments in affiliated securities, at fair value1‡		23,893,867			42,959,421		13,159,284		108,059,104		–			–		–
Cash		–			–		–		16		–			–		–
Receivables:
Investments sold		840,778			2,995,321		1,290,477		–		–			–		–
Fund shares sold		4,772			22,456		15,047		4,270		332			8,744		14,349
Dividends and Interest		64,770			90,310		18,757		94		381,174			115,914		200,070
Total Assets		48,630,063			108,611,957		44,781,683		145,280,054		54,015,764			164,992,499		181,004,227
Liabilities:
Payables:
Investments purchased		704,745			3,058,598		1,448,329		–		–			–		–
Fund shares repurchased		9,801			12,529		4,295		71,255		29,368			94,662		93,520
Upon return of securities loaned		913,695			3,545,191		1,931,648		1,088,375		196,490			–		–
Advisory agreement fees		11,577			24,896		10,058		29,455		26,293			83,163		121,671
Trustee fees		4,561			9,777		3,776		13,671		6,367			17,344		19,537
Distribution fees - Class II		1,595			1,668		98		3,637		2,315			322		1,624
Due to custodian		–			–		–		–		–			–		7,541
Total Liabilities		1,645,974			6,652,659		3,398,204		1,206,393		260,833			195,491		243,893
Commitments and Contingencies (Note 2)
Net assets	$	46,984,089		$	101,959,298	$	41,383,479	$	144,073,661	$	53,754,931		$	164,797,008	$	180,760,334
Net assets consist of:
Paid-in capital	$	50,541,637		$	88,593,468	$	34,495,520	$	138,334,068	$	62,503,045		$	120,874,794	$	79,485,087
Accumulated distributable earnings (loss)		(3,557,548	)		13,365,830		6,887,959		5,739,593		(8,748,114	)		43,922,214		101,275,247
Net Assets	$	46,984,089		$	101,959,298	$	41,383,479	$	144,073,661	$	53,754,931		$	164,797,008	$	180,760,334
Class I Shares:
Net Assets	$	39,155,142		$	93,741,204	$	40,894,649	$	126,162,483	$	42,454,141		$	163,230,225	$	172,825,184
Shares of beneficial interest outstanding		4,112,838			10,052,973		4,914,483		9,122,788		4,989,234			6,714,202		7,415,552
Net Asset Value and redemption price per share	$	9.52		$	9.32	$	8.32	$	13.83	$	8.51		$	24.31	$	23.31
Class II Shares:
Net Assets	$	7,828,947		$	8,218,094	$	488,830	$	17,911,178	$	11,300,790		$	1,566,783	$	7,935,150
Shares of beneficial interest outstanding		817,912			877,692		58,803		1,320,530		1,336,763			65,803		354,866
Net Asset Value and redemption price per share	$	9.57		$	9.36	$	8.31	$	13.56	$	8.45		$	23.81	$	22.36
† Cost of Investments in unaffiliated securities	$	21,743,447		$	56,114,265	$	26,882,392	$	36,361,849	$	56,902,496		$	127,265,847	$	103,471,076
‡ Cost of investments in affiliated securities1	$	24,058,453		$	37,700,465	$	10,130,973	$	105,677,294	$	–		$	–	$	–
§ Fair Value of securities on loan	$	1,678,713		$	3,824,490	$	2,075,446	$	7,115,160	$	193,305		$	–	$	5,339,463

See accompanying Notes to Financial Statements.

19

Ultra Series Fund | June 30, 2025

Statements of Assets and Liabilities as of June 30, 2025 (unaudited) - concluded

	Mid Cap Fund		Madison Target Retirement 2020 Fund			Madison Target Retirement 2030 Fund		Madison Target Retirement 2040 Fund		Madison Target Retirement 2050 Fund
Assets:
Investments in unaffiliated securities, at fair value†§	$	122,249,637	$	10,972,142		$	50,919,355	$	42,356,163	$	36,479,637
Cash		1,428		–			–		–		–
Receivables:
Fund shares sold		5,940		3,770			27,003		35,329		28,416
Dividends and Interest		46,941		–			–		–		–
Total Assets		122,303,946		10,975,912			50,946,358		42,391,492		36,508,053
Liabilities:
Payables:
Fund shares repurchased		56,159		–			–		–		–
Advisory agreement fees		94,404		2,266			10,260		8,478		7,305
Trustee fees		13,828		49			183		145		126
Administrative service agreement fees		–		453			2,052		1,695		1,461
Distribution fees - Class II		710		–			–		–		–
Total Liabilities		165,101		2,768			12,495		10,318		8,892
Commitments and Contingencies (Note 2)
Net assets	$	122,138,845	$	10,973,144		$	50,933,863	$	42,381,174	$	36,499,161
Net assets consist of:
Paid-in capital	$	50,786,711	$	13,310,974		$	49,878,605	$	39,110,502	$	32,870,856
Accumulated distributable earnings (loss)		71,352,134		(2,337,830	)		1,055,258		3,270,672		3,628,305
Net Assets	$	122,138,845	$	10,973,144		$	50,933,863	$	42,381,174	$	36,499,161
Class I Shares:
Net Assets	$	118,635,801	$	10,973,144		$	50,933,863	$	42,381,174	$	36,499,161
Shares of beneficial interest outstanding		7,295,563		1,643,435			6,764,991		5,905,055		2,852,319
Net Asset Value and redemption price per share	$	16.26	$	6.68		$	7.53	$	7.18	$	12.80
Class II Shares:
Net Assets	$	3,503,044
Shares of beneficial interest outstanding		233,826
Net Asset Value and redemption price per share	$	14.98
† Cost of Investments in unaffiliated securities	$	62,381,346	$	10,459,672		$	46,782,589	$	37,980,417	$	32,006,819
§ Fair Value of securities on loan	$	2,932,825	$	–		$	–	$	–	$	–

See accompanying Notes to Financial Statements.

20

Ultra Series Fund | June 30, 2025

Statements of Operations for the Six Months Ended June 30, 2025 (unaudited)

	Conservative Allocation Fund			Moderate Allocation Fund		Aggressive Allocation Fund		Diversified Income Fund			Core Bond Fund			Large Cap Value Fund		Large Cap Growth Fund
Investment Income:
Interest	$	17,159		$	48,095	$	23,982	$	24,379		$	1,350,394		$	60,773	$	107,379
Dividends
Unaffiliated issuers		309,961			657,516		260,388		958,998			–			2,241,774		970,034
Affiliated issuers1		378,626			527,927		109,149		2,353,895			–			–		–
Less: Foreign taxes withheld/reclaimed		–			–		–		1,597			–			–		(38	)
Income from securities lending		5,541			15,588		6,976		24,309			598			–		2,093
Total Investment Income		711,287			1,249,126		400,495		3,363,178			1,350,992			2,302,547		1,079,468
Expenses:2
Advisory agreement fees		70,831			153,356		59,918		180,875			172,883			521,825		769,153
Trustee fees		1,567			3,377		1,297		4,694			2,186			5,955		6,708
Audit fees		4,398			9,423		3,639		13,178			6,136			16,718		18,831
Distribution fees - Class II		9,858			10,356		581		22,705			14,456			2,106		10,297
Total Expenses		86,654			176,512		65,435		221,452			195,661			546,604		804,989
Net Investment Income (loss)		624,633			1,072,614		335,060		3,141,726			1,155,331			1,755,943		274,479
Net Realized and Unrealized Gain (loss) on Investments
Net realized gain (loss) on investments (including net realized gain (loss) on foreign currency related transactions)
Unaffiliated issuers		120,034			368,201		88,937		123,168			(836,262	)		4,588,316		24,312,799
Affiliated issuers1		(11,240	)		640,992		102,931		(761,831	)		–			–		–
Net change in unrealized appreciation (depreciation) on investments (including net unrealized appreciation (depreciation) on foreign currency related transactions)
Unaffiliated issuers		1,023,962			2,764,612		1,561,098		482,798			1,997,007			1,413,044		(20,757,995	)
Affiliated Issuers1		493,670			200,849		142,159		2,239,559			–			–		–
Net Realized and Unrealized Gain on Investments		1,626,426			3,974,654		1,895,125		2,083,694			1,160,745			6,001,360		3,554,804
Net Increase in Net Assets from Operations	$	2,251,059		$	5,047,268	$	2,230,185	$	5,225,420		$	2,316,076		$	7,757,303	$	3,829,283

¹ See Note 10 for information on affiliated issuers. 

² See Note 4 for information on expenses.

See accompanying Notes to Financial Statements.

21

Ultra Series Fund | June 30, 2025

Statements of Operations for the Six Months Ended June 30, 2025 (unaudited) - concluded

	Mid Cap Fund			Madison Target Retirement 2020 Fund		Madison Target Retirement 2030 Fund		Madison Target Retirement 2040 Fund		Madison Target Retirement 2050 Fund
Investment Income:
Interest	$	113,454		$	6,925	$	32,575	$	33,556	$	30,830
Dividends
Unaffiliated issuers		559,707			180,670		686,030		460,686		359,565
Less: Foreign taxes withheld/reclaimed		(8,113	)		–		–		–		–
Income from securities lending		639			–		–		–		–
Total Investment Income		665,687			187,595		718,605		494,242		390,395
Expenses:1
Advisory agreement fees		598,960			14,342		61,385		49,619		42,692
Administrative services agreement fees		–			2,868		12,278		9,924		8,538
Trustee fees		4,747			460		1,729		1,377		1,201
Audit fees		13,330			–		–		–		–
Distribution fees - Class II		4,488			–		–		–		–
Total Expenses		621,525			17,670		75,392		60,920		52,431
Net Investment Income (loss)		44,162			169,925		643,213		433,322		337,964
Net Realized and Unrealized Gain (loss) on Investments
Net realized gain (loss) on investments (including net realized gain (loss) on foreign currency related transactions)
Unaffiliated issuers		11,581,418			79,754		615,589		472,166		520,732
Net change in unrealized appreciation (depreciation) on investments (including net unrealized appreciation (depreciation) on foreign currency related transactions)
Unaffiliated issuers		(11,192,420	)		274,954		1,267,963		1,354,234		1,162,023
Net Realized and Unrealized Gain on Investments		388,998			354,708		1,883,552		1,826,400		1,682,755
Net Increase in Net Assets from Operations	$	433,160		$	524,633	$	2,526,765	$	2,259,722	$	2,020,719

¹ See Note 4 for information on expenses.

See accompanying Notes to Financial Statements.

22

Ultra Series Fund | June 30, 2025

Statements of Changes in Net Assets

	Conservative Allocation Fund						Moderate Allocation Fund						Aggressive Allocation Fund						Diversified Income Fund
	(unaudited) Six-Months Ended 6/30/25			Year Ended 12/31/24			(unaudited) Six-Months Ended 6/30/25			Year Ended 12/31/24			(unaudited) Six-Months Ended 6/30/25			Year Ended 12/31/24			(unaudited) Six-Months Ended 6/30/25			Year Ended 12/31/24
Net Assets at beginning of period	$	48,543,182		$	111,074,178		$	107,456,391		$	113,197,461		$	40,904,435		$	38,914,936		$	150,344,792		$	172,144,683
Increase (decrease) in net assets from operations:
Net investment income		624,633			1,971,711			1,072,614			2,839,399			335,060			916,417			3,141,726			9,932,248
Net realized gain (loss)		108,794			1,428,929			1,009,193			5,528,818			191,868			2,228,660			(638,663	)		2,011,641
Net change in unrealized appreciation (depreciation)		1,517,632			(1,063,447	)		2,965,461			(333,110	)		1,703,257			353,775			2,722,357			(3,883,159	)
Net increase (decrease) in net assets from operations		2,251,059			2,337,193			5,047,268			8,035,107			2,230,185			3,498,852			5,225,420			8,060,730
Distributions to shareholders from:
Accumulated earnings (combined net investment income and net realized gains):
Class I		(180,155	)		(1,744,278	)		(1,392,195	)		(4,489,967	)		(677,288	)		(2,218,430	)		(1,759,622	)		(11,871,448	)
Class II		(26,819	)		(334,778	)		(111,968	)		(378,546	)		(7,497	)		(24,491	)		(232,179	)		(1,714,884	)
Total distributions		(206,974	)		(2,079,056	)		(1,504,163	)		(4,868,513	)		(684,785	)		(2,242,921	)		(1,991,801	)		(13,586,332	)
Capital Stock transactions:
Class I Shares
Shares sold		1,856,746			3,383,063			2,571,014			6,933,880			2,361,706			4,219,658			1,090,981			2,037,897
Issued to shareholders in reinvestment of distributions		180,155			1,744,278			1,392,195			4,489,967			677,288			2,218,430			1,759,622			11,871,448
Shares redeemed		(4,985,836	)		(65,894,219	)		(12,282,235	)		(18,719,800	)		(4,109,664	)		(5,682,570	)		(10,707,971	)		(28,122,240	)
Net increase (decrease) from capital stock transactions		(2,948,935	)		(60,766,878	)		(8,319,026	)		(7,295,953	)		(1,070,670	)		755,518			(7,857,368	)		(14,212,895	)
Class II Shares
Shares sold		1,529			56,708			120,879			186,263			22			16,223			211,263			265,438
Issued to shareholders in reinvestment of distributions		26,819			334,778			111,968			378,546			7,497			24,491			232,179			1,714,884
Shares redeemed		(682,591	)		(2,413,741	)		(954,019	)		(2,176,520	)		(3,205	)		(62,664	)		(2,090,824	)		(4,041,716	)
Net increase (decrease) from capital stock transactions		(654,243	)		(2,022,255	)		(721,172	)		(1,611,711	)		4,314			(21,950	)		(1,647,382	)		(2,061,394	)
Total increase (decrease) from capital stock transactions		(3,603,178	)		(62,789,133	)		(9,040,198	)		(8,907,664	)		(1,066,356	)		733,568			(9,504,750	)		(16,274,289	)
Total increase (decrease) in net assets		(1,559,093	)		(62,530,996	)		(5,497,093	)		(5,741,070	)		479,044			1,989,499			(6,271,131	)		(21,799,891	)
Net Assets at end of period	$	46,984,089		$	48,543,182		$	101,959,298		$	107,456,391		$	41,383,479		$	40,904,435		$	144,073,661		$	150,344,792
Capital Share transactions:
Class I Shares
Shares sold		200,735			361,477			285,873			763,359			295,905			512,729			79,956			143,005
Issued to shareholders in reinvestment of distributions		19,118			190,643			150,897			497,787			82,314			276,419			128,096			871,603
Shares redeemed		(537,316	)		(7,256,887	)		(1,365,714	)		(2,027,786	)		(514,162	)		(689,419	)		(785,631	)		(1,975,340	)
Net increase (decrease) from capital share transactions		(317,463	)		(6,704,767	)		(928,944	)		(766,640	)		(135,943	)		99,729			(577,579	)		(960,732	)
Class II Shares
Shares sold		165			6,113			13,761			20,064			3			1,958			15,781			19,265
Issued to shareholders in reinvestment of distributions		2,830			36,394			12,085			41,810			911			3,056			17,231			128,311
Shares redeemed		(73,231	)		(257,135	)		(104,665	)		(234,087	)		(397	)		(7,535	)		(157,405	)		(288,936	)
Net increase (decrease) from capital share transactions		(70,236	)		(214,628	)		(78,819	)		(172,213	)		517			(2,521	)		(124,393	)		(141,360	)

See accompanying Notes to Financial Statements.

23 

Ultra Series Fund | June 30, 2025

Statements of Changes in Net Assets - continued

	Core Bond Fund						Large Cap Value Fund						Large Cap Growth Fund						Mid Cap Fund
	(unaudited) Six-Months Ended 6/30/25			Year Ended 12/31/24			(unaudited) Six-Months Ended 6/30/25			Year Ended 12/31/24			(unaudited) Six-Months Ended 6/30/25			Year Ended 12/31/24			(unaudited) Six-Months Ended 6/30/25			Year Ended 12/31/24
Net Assets at beginning of period	$	65,265,261		$	74,971,185		$	178,530,894		$	187,890,218		$	200,341,889		$	198,875,493		$	141,923,374		$	153,760,056
Increase (decrease) in net assets from operations:
Net investment income		1,155,331			2,427,512			1,755,943			4,129,178			274,479			1,263,242			44,162			985,812
Net realized gain (loss)		(836,262	)		(1,443,887	)		4,588,316			3,211,076			24,312,799			15,738,402			11,581,418			24,948,718
Net change in unrealized appreciation (depreciation)		1,997,007			(111,466	)		1,413,044			6,719,032			(20,757,995	)		13,971,994			(11,192,420	)		(10,178,967	)
Net increase (decrease) in net assets from operations		2,316,076			872,159			7,757,303			14,059,286			3,829,283			30,973,638			433,160			15,755,563
Distributions to shareholders from:
Accumulated earnings (combined net investment income and net realized gains):
Class I		(199,488	)		(1,995,876	)		(841,152	)		(8,870,244	)		(1,632,179	)		(16,379,149	)		(6,454,535	)		(24,305,650	)
Class II		(30,161	)		(421,072	)		(5,802	)		(89,488	)		(67,814	)		(766,810	)		(186,945	)		(718,562	)
Total distributions		(229,649	)		(2,416,948	)		(846,954	)		(8,959,732	)		(1,699,993	)		(17,145,959	)		(6,641,480	)		(25,024,212	)
Capital Stock transactions:
Class I Shares:
Shares sold		1,263,541			2,805,757			1,495,506			2,496,858			1,577,514			3,079,481			1,405,978			2,298,541
Issued to shareholders in reinvestment of distributions		199,488			1,995,876			841,152			8,870,244			1,632,179			16,379,149			6,454,535			24,305,650
Shares redeemed		(14,045,576	)		(11,819,646	)		(22,659,158	)		(25,586,445	)		(24,067,760	)		(30,051,555	)		(21,286,080	)		(28,702,782	)
Net decrease from capital stock transactions		(12,582,547	)		(7,018,013	)		(20,322,500	)		(14,219,343	)		(20,858,067	)		(10,592,925	)		(13,425,567	)		(2,098,591	)
Class II Shares:
Shares sold		148,356			147,116			19,518			15,647			22,185			27,170			21,949			21,147
Issued to shareholders in reinvestment of distributions		30,161			421,072			5,802			89,488			67,814			766,810			186,945			718,562
Shares redeemed		(1,192,727	)		(1,711,310	)		(347,055	)		(344,670	)		(942,777	)		(2,562,338	)		(359,536	)		(1,209,151	)
Net decrease from capital stock transactions		(1,014,210	)		(1,143,122	)		(321,735	)		(239,535	)		(852,778	)		(1,768,358	)		(150,642	)		(469,442	)
Total decrease from capital stock transactions		(13,596,757	)		(8,161,135	)		(20,644,235	)		(14,458,878	)		(21,710,845	)		(12,361,283	)		(13,576,209	)		(2,568,033	)
Total increase decrease in net assets		(11,510,330	)		(9,705,924	)		(13,733,886	)		(9,359,324	)		(19,581,555	)		1,466,396			(19,784,529	)		(11,836,682	)
Net Assets at end of period	$	53,754,931		$	65,265,261		$	164,797,008		$	178,530,894		$	180,760,334		$	200,341,889		$	122,138,845		$	141,923,374
Capital Share transactions:
Class I Shares:
Shares sold		151,710			331,685			62,501			107,274			67,986			129,936			84,195			119,025
Issued to shareholders in reinvestment of distributions		23,674			241,610			34,745			386,140			70,332			713,000			401,664			1,403,146
Shares redeemed		(1,671,520	)		(1,414,000	)		(945,932	)		(1,093,316	)		(1,041,326	)		(1,266,148	)		(1,302,985	)		(1,487,237	)
Net increase decrease from capital share transactions		(1,496,136	)		(840,705	)		(848,686	)		(599,902	)		(903,008	)		(423,212	)		(817,126	)		34,934
Class II Shares:
Shares sold		17,762			17,790			822			702			962			1,226			1,424			1,155
Issued to shareholders in reinvestment of distributions		3,602			51,321			245			3,975			3,045			34,743			12,626			44,671
Shares redeemed		(143,443	)		(204,342	)		(14,936	)		(15,040	)		(42,521	)		(112,943	)		(23,293	)		(66,662	)
Net decrease from capital share transactions		(122,079	)		(135,231	)		(13,869	)		(10,363	)		(38,514	)		(76,974	)		(9,243	)		(20,836	)

See accompanying Notes to Financial Statements.

24 

Ultra Series Fund | June 30, 2025

Statements of Changes in Net Assets - concluded

	Madison Target Retirement 2020 Fund						Madison Target Retirement 2030 Fund						Madison Target Retirement 2040 Fund						Madison Target Retirement 2050 Fund
	(unaudited) Six-Months Ended 6/30/25			Year Ended 12/31/24			(unaudited) Six-Months Ended 6/30/25			Year Ended 12/31/24			(unaudited) Six-Months Ended 6/30/25			Year Ended 12/31/24			(unaudited) Six-Months Ended 6/30/25			Year Ended 12/31/24
Net Assets at beginning of period	$	13,714,523		$	15,409,894		$	51,648,653		$	55,774,944		$	41,179,759		$	38,064,139		$	35,846,052		$	32,365,350
Increase (decrease) in net assets from operations:
Net investment income		169,925			504,497			643,213			1,612,348			433,322			999,615			337,964			779,504
Net realized gain (loss)		79,754			173,565			615,589			1,007,885			472,166			1,018,491			520,732			814,813
Net change in unrealized appreciation (depreciation)		274,954			(173,175	)		1,267,963			370,646			1,354,234			928,740			1,162,023			1,339,762
Net increase (decrease) in net assets from operations		524,633			504,887			2,526,765			2,990,879			2,259,722			2,946,846			2,020,719			2,934,079
Distributions to shareholders from:
Accumulated earnings (combined net investment income and net realized gains):
Class I		(49,790	)		(480,656	)		(168,970	)		(1,443,378	)		(120,796	)		(878,819	)		(102,816	)		(676,688	)
Total distributions		(49,790	)		(480,656	)		(168,970	)		(1,443,378	)		(120,796	)		(878,819	)		(102,816	)		(676,688	)
Capital Stock transactions:
Class I Shares:
Shares sold		936,701			1,448,155			3,327,560			6,187,726			3,770,846			7,662,200			3,032,258			5,611,645
Issued to shareholders in reinvestment of distributions		49,790			480,656			168,970			1,443,378			120,796			878,819			102,816			676,688
Shares redeemed		(4,202,713	)		(3,648,413	)		(6,569,115	)		(13,304,896	)		(4,829,153	)		(7,493,426	)		(4,399,868	)		(5,065,022	)
Net decrease from capital stock transactions		(3,216,222	)		(1,719,602	)		(3,072,585	)		(5,673,792	)		(937,511	)		1,047,593			(1,264,794	)		1,223,311
Total decrease from capital stock transactions		(3,216,222	)		(1,719,602	)		(3,072,585	)		(5,673,792	)		(937,511	)		1,047,593			(1,264,794	)		1,223,311
Total increase (decrease) in net assets		(2,741,379	)		(1,695,371	)		(714,790	)		(4,126,291	)		1,201,415			3,115,620			653,109			3,480,702
Net Assets at end of period	$	10,973,144		$	13,714,523		$	50,933,863		$	51,648,653		$	42,381,174		$	41,179,759		$	36,499,161		$	35,846,052
Capital Share transactions:
Class I Shares
Shares sold		144,200			221,229			456,433			857,453			546,743			1,126,403			245,944			468,469
Issued to shareholders in reinvestment of distributions		7,531			75,285			22,678			201,491			17,024			129,385			8,130			56,031
Shares redeemed		(651,608	)		(557,946	)		(902,337	)		(1,827,812	)		(703,727	)		(1,103,747	)		(361,390	)		(423,104	)
Net increase (decrease) from capital share transactions		(499,877	)		(261,432	)		(423,226	)		(768,868	)		(139,960	)		152,041			(107,316	)		101,396

See accompanying Notes to Financial Statements.

25

Ultra Series Fund | June 30, 2025

Financial Highlights for a Share of Beneficial Interest Outstanding

CONSERVATIVE ALLOCATION FUND

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended
	6/30/25			2024			2023			2022			2021			2020
CLASS I
Net Asset Value at beginning of period	$	9.12		$	9.07		$	8.61		$	10.40		$	10.33		$	10.13
Income from Investment Operations:
Net investment income		0.13	1		0.27	1		0.26			0.18			0.23			0.12
Net realized and unrealized gain (loss) on investments		0.31			0.19			0.46			(1.54	)		0.15			0.83
Total from investment operations		0.44			0.46			0.72			(1.36	)		0.38			0.95
Less Distributions From:
Net investment income		(0.04	)		(0.41	)		(0.26	)		(0.18	)		(0.21	)		(0.22	)
Capital gains		–			–			–			(0.25	)		(0.10	)		(0.41	)
Return of Capital		–			–			–			–			–			(0.12	)
Total distributions		(0.04	)		(0.41	)		(0.26	)		(0.43	)		(0.31	)		(0.75	)
Net increase (decrease) in net asset value		0.40			0.05			0.46			(1.79	)		0.07			0.20
Net Asset Value at end of period	$	9.52		$	9.12		$	9.07		$	8.61		$	10.40		$	10.33
Total Return (%)2		4.883			4.99			8.33			(13.17	)		3.59			9.46
Ratios/Supplemental Data:
Net Assets at end of period (in 000’s)	$	39,155		$	40,399		$	101,017		$	102,727		$	134,456		$	146,016
Ratios of expenses to average net assets:
Before waiver of expenses by Adviser (%)		0.33	4		0.32			0.32			0.33			0.32			0.32
After waiver of expenses by Adviser (%)		0.33	4		0.32			0.32			0.29			0.22			0.22
Ratio of net investment income to average net assets :
Before reimbursement of expenses by Advisor (%)		2.69	4		2.88			2.77			1.70			1.94			1.46
After reimbursement of expenses by Advisor (%)		2.69	4		2.88			2.77			1.74			2.04			1.56
Portfolio turnover (%)5		19	3		48			49			64			50			73

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended
	6/30/25			2024			2023			2022			2021			2020
CLASS II
Net Asset Value at beginning of period	$	9.17		$	9.12		$	8.65		$	10.42		$	10.36		$	10.14
Income from Investment Operations:
Net investment income		0.11	1		0.27	1		0.21			0.13			0.19			0.13
Net realized and unrealized gain (loss) on investments		0.32			0.16			0.48			(1.51	)		0.15			0.80
Total from investment operations		0.43			0.43			0.69			(1.38	)		0.34			0.93
Less Distributions From:
Net investment income		(0.03	)		(0.38	)		(0.22	)		(0.14	)		(0.18	)		(0.18	)
Capital gains		–			–			–			(0.25	)		(0.10	)		(0.41	)
Return of Capital		–			–			–			–			(0.12	)		–
Total distributions		(0.03	)		(0.38	)		(0.22	)		(0.39	)		(0.28	)		(0.71	)
Net increase (decrease) in net asset value		0.40			0.05			0.47			(1.77	)		0.06			0.22
Net Asset Value at end of period	$	9.57		$	9.17		$	9.12		$	8.65		$	10.42		$	10.36
Total Return (%)2		4.753			4.74			8.06			(13.38	)		3.33			9.18
Ratios/Supplemental Data:
Net Assets at end of period (in 000’s)	$	7,829		$	8,144		$	10,057		$	12,679		$	17,373		$	19,406
Ratios of expenses to average net assets:
Before waiver of expenses by Adviser (%)		0.58	4		0.57			0.57			0.58			0.57			0.57
After waiver of expenses by Adviser (%)		0.58	4		0.57			0.57			0.54			0.47			0.47
Ratio of net investment income to average net assets :
Before reimbursement of expenses by Advisor (%)		2.444			2.91			2.46			1.44			1.69			1.20
After reimbursement of expenses by Advisor (%)		2.444			2.91			2.46			1.48			1.79			1.30
Portfolio turnover (%)5		193			48			49			64			50			73

¹ Per share amounts have been calculated using the average shares method. 

² These returns are after all charges at the mutual fund level have been subtracted. These returns are higher than the returns at the separate account level because charges made at the separate account level have not been subtracted. Total returns are not annualized for periods less than one year. 

³ Not annualized. 

⁴ Annualized. 

⁵ Portfolio turnover is calculated at the fund level and represents the entire fiscal year or period.

See accompanying Notes to Financial Statements.

26

Ultra Series Fund | June 30, 2025

Financial Highlights for a Share of Beneficial Interest Outstanding - continued

MODERATE ALLOCATION FUND

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended
	6/30/25			2024			2023			2022			2021			2020
CLASS I
Net Asset Value at beginning of period	$	9.00		$	8.79		$	8.13		$	10.29		$	10.09		$	10.31
Income from Investment Operations:
Net investment income		0.10	1		0.24	1		0.22			0.15			0.28			0.15
Net realized and unrealized gain (loss) on investments		0.35			0.40			0.67			(1.53	)		0.46			0.89
Total from investment operations		0.45			0.64			0.89			(1.38	)		0.74			1.04
Less Distributions From:
Net investment income		(0.02	)		(0.25	)		(0.22	)		(0.16	)		(0.26	)		(0.17	)
Capital gains		(0.11	)		(0.18	)		(0.01	)		(0.62	)		(0.28	)		(0.78	)
Return of Capital		–			–			–			–			–			(0.31	)
Total distributions		(0.13	)		(0.43	)		(0.23	)		(0.78	)		(0.54	)		(1.26	)
Net increase (decrease) in net asset value		0.32			0.21			0.66			(2.16	)		0.20			(0.22	)
Net Asset Value at end of period	$	9.32		$	9.00		$	8.79		$	8.13		$	10.29		$	10.09
Total Return (%)2		5.19	3		7.34			10.82			(13.54	)		7.40			10.06
Ratios/Supplemental Data:
Net Assets at end of period (in 000’s)	$	93,741		$	98,814		$	103,239		$	107,664		$	146,647		$	161,944
Ratios of expenses to average net assets:
Before waiver of expenses by Adviser (%)		0.33	4		0.32			0.32			0.33			0.32			0.32
After waiver of expenses by Adviser (%)		0.33	4		0.32			0.32			0.29			0.22			0.22
Ratio of net investment income to average net assets :
Before reimbursement of expenses by Advisor (%)		2.12	4		2.57			2.38			1.54			2.27			1.22
After reimbursement of expenses by Advisor (%)		2.12	4		2.57			2.38			1.58			2.37			1.32
Portfolio turnover (%)5		25	3		50			57			64			59			79

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended
	6/30/25			2024			2023			2022			2021			2020
CLASS II
Net Asset Value at beginning of period	$	9.04		$	8.82		$	8.16		$	10.31		$	10.10		$	10.31
Income from Investment Operations:
Net investment income		0.08	1		0.21	1		0.13			0.09			0.21			0.11
Net realized and unrealized gain (loss) on investments		0.36			0.42			0.73			(1.49	)		0.51			0.90
Total from investment operations		0.44			0.63			0.86			(1.40	)		0.72			1.01
Less Distributions From:
Net investment income		(0.01	)		(0.23	)		(0.19	)		(0.13	)		(0.23	)		(0.13	)
Capital gains		(0.11	)		(0.18	)		(0.01	)		(0.62	)		(0.28	)		(0.78	)
Return of Capital		–			–			–			–			–			(0.31	)
Total distributions		(0.12	)		(0.41	)		(0.20	)		(0.75	)		(0.51	)		(1.22	)
Net increase (decrease) in net asset value		0.32			0.22			0.66			(2.15	)		0.21			(0.21	)
Net Asset Value at end of period	$	9.36		$	9.04		$	8.82		$	8.16		$	10.31		$	10.10
Total Return (%)2		5.06	3		7.07			10.54			(13.76	)		7.13			9.78
Ratios/Supplemental Data:
Net Assets at end of period (in 000s)	$	8,218		$	8,643		$	9,958		$	11,241		$	16,166		$	18,046
Ratios of expenses to average net assets:
Before waiver of expenses by Adviser (%)		0.58	4		0.57			0.57			0.58			0.57			0.57
After waiver of expenses by Adviser (%)		0.58	4		0.57			0.57			0.54			0.47			0.47
Ratio of net investment income to average net assets :
Before reimbursement of expenses by Advisor (%)		1.87	4		2.27			2.11			1.28			2.07			0.97
After reimbursement of expenses by Advisor (%)		1.87	4		2.27			2.11			1.32			2.17			1.07
Portfolio turnover (%)5		25	3		50			57			64			59			79

¹ Per share amounts have been calculated using the average shares method. 

² These returns are after all charges at the mutual fund level have been subtracted. These returns are higher than the returns at the separate account level because charges made at the separate account level have not been subtracted. Total returns are not annualized for periods less than one year. 

³ Not annualized. 

⁴ Annualized. 

⁵ Portfolio turnover is calculated at the fund level and represents the entire fiscal year or period.

See accompanying Notes to Financial Statements.

27

Ultra Series Fund | June 30, 2025

Financial Highlights for a Share of Beneficial Interest Outstanding - continued

AGGRESSIVE ALLOCATION FUND

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended
	6/30/25			2024			2023			2022			2021			2020
CLASS I
Net Asset Value at beginning of period	$	8.01		$	7.77		$	7.04		$	9.08		$	8.76		$	9.09
Income from Investment Operations:
Net investment income		0.07	1		0.19	1		0.18			0.13			0.28			0.12
Net realized and unrealized gain (loss) on investments		0.38			0.51			0.73			(1.39	)		0.61			0.79
Total from investment operations		0.45			0.70			0.91			(1.26	)		0.89			0.91
Less Distributions From:
Net investment income		(0.02	)		(0.19	)		(0.18	)		(0.14	)		(0.26	)		(0.13	)
Capital gains		(0.12	)		(0.27	)		(0.00	)2		(0.64	)		(0.31	)		(0.72	)
Return of Capital		–			–			–			–			–			(0.39	)
Total distributions		(0.14	)		(0.46	)		(0.18	)		(0.78	)		(0.57	)		(1.24	)
Net increase (decrease) in net asset value		0.31			0.24			0.73			(2.04	)		0.32			(0.33	)
Net Asset Value at end of period	$	8.32		$	8.01		$	7.77		$	7.04		$	9.08		$	8.76
Total Return (%)3		5.68	4		9.08			12.88			(14.35	)		10.18			10.08
Ratios/Supplemental Data:
Net Assets at end of period (in 000’s)	$	40,895		$	40,438		$	38,443		$	39,149		$	52,574		$	54,472
Ratios of expenses to average net assets:
Before waiver of expenses by Adviser (%)		0.32	5		0.33			0.32			0.33			0.32			0.32
After waiver of expenses by Adviser (%)		0.32	5		0.33			0.32			0.29			0.22			0.22
Ratio of net investment income to average net assets :
Before reimbursement of expenses by Advisor (%)		1.68	5		2.25			2.14			1.46			2.64			1.04
After reimbursement of expenses by Advisor (%)		1.68	5		2.25			2.14			1.50			2.74			1.14
Portfolio turnover (%)6		27	4		60			64			70			71			93

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended
	6/30/25			2024			2023			2022			2021			2020
CLASS II
Net Asset Value at beginning of period	$	8.00		$	7.76		$	7.02		$	9.06		$	8.74		$	9.06
Income from Investment Operations:
Net investment income		0.06	1		0.16	1		0.14			0.10			0.22			0.08
Net realized and unrealized gain (loss) on investments		0.38			0.52			0.75			(1.39	)		0.64			0.80
Total from investment operations		0.44			0.68			0.89			(1.29	)		0.86			0.88
Less Distributions From:
Net investment income		(0.01	)		(0.17	)		(0.15	)		(0.11	)		(0.23	)		(0.09	)
Capital gains		(0.12	)		(0.27	)		(0.00	)2		(0.64	)		(0.31	)		(0.72	)
Return of Capital		–			–			–			–			–			(0.39	)
Total distributions		(0.13	)		(0.44	)		(0.15	)		(0.75	)		(0.54	)		(1.20	)
Net increase (decrease) in net asset value		0.31			0.24			0.74			(2.04	)		0.32			(0.32	)
Net Asset Value at end of period	$	8.31		$	8.00		$	7.76		$	7.02		$	9.06		$	8.74
Total Return (%)3		5.554			8.81			12.60			(14.57	)		9.90			9.81
Ratios/Supplemental Data:
Net Assets at end of period (in 000’s)	$	489		$	466		$	472		$	614		$	799		$	1,095
Ratios of expenses to average net assets:
Before waiver of expenses by Adviser (%)		0.57	5		0.58			0.57			0.58			0.57			0.57
After waiver of expenses by Adviser (%)		0.57	5		0.58			0.57			0.54			0.47			0.47
Ratio of net investment income to average net assets :
Before reimbursement of expenses by Advisor (%)		1.44	5		1.95			1.84			1.23			2.32			0.80
After reimbursement of expenses by Advisor (%)		1.44	5		1.95			1.84			1.27			2.42			0.90
Portfolio turnover (%)6		27	4		60			64			70			71			93

¹Per share amounts have been calculated using the average shares method. 

²Amounts represent less than $ (0.005) per share. 

³These returns are after all charges at the mutual fund level have been subtracted. These returns are higher than the returns at the separate account level because charges made at the separate account level have not been subtracted. Total returns are not annualized for periods less than one year. 

⁴Not annualized. 

⁵Annualized. 

⁶Portfolio turnover is calculated at the fund level and represents the entire fiscal year or period.

See accompanying Notes to Financial Statements.

28

Ultra Series Fund | June 30, 2025

Financial Highlights for a Share of Beneficial Interest Outstanding - continued

DIVERSIFIED INCOME FUND

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended
	6/30/25			2024			2023			2022			2021			2020
CLASS I
Net Asset Value at beginning of period	$	13.52		$	14.09		$	16.09		$	19.65		$	19.47		$	19.11
Income from Investment Operations:
Net investment income		0.29	1		0.89	1		0.45			0.41			0.36			0.40
Net realized and unrealized gain (loss) on investments		0.21			(0.17	)		0.14			(1.89	)		2.53			1.04
Total from investment operations		0.50			0.72			0.59			(1.48	)		2.89			1.44
Less Distributions From:
Net investment income		(0.18	)		(0.89	)		(0.44	)		(0.41	)		(0.39	)		(0.41	)
Capital gains		(0.01	)		(0.40	)		(2.15	)		(1.67	)		(2.32	)		(0.67	)
Total distributions		(0.19	)		(1.29	)		(2.59	)		(2.08	)		(2.71	)		(1.08	)
Net increase (decrease) in net asset value		0.31			(0.57	)		(2.00	)		(3.56	)		0.18			0.36
Net Asset Value at end of period	$	13.83		$	13.52		$	14.09		$	16.09		$	19.65		$	19.47
Total Return (%)2		3.71	3		5.24			3.77			(7.64	)		14.92			7.77
Ratios/Supplemental Data:
Net Assets at end of period (in 000’s)	$	126,162		$	131,174		$	150,186		$	166,136		$	200,806		$	195,463
Ratios of expenses to average net assets (%)		0.27	4		0.27			0.54			0.73			0.72			0.72
Ratio of net investment income to average net assets (%)		4.38	4		6.22			2.72			2.18			1.64			2.04
Portfolio turnover (%)5		16	3		11			118			32			34			31

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended
	6/30/25			2024			2023			2022			2021			2020
CLASS II
Net Asset Value at beginning of period	$	13.27		$	13.84		$	15.85		$	19.39		$	19.27		$	18.92
Net investment income		0.28	1		0.84	1		0.42			0.37			0.32			0.27
Net realized and unrealized gain (loss) on investments		0.19			(0.16	)		0.12			(1.88	)		2.48			1.12
Total from investment operations		0.47			0.68			0.54			(1.51	)		2.80			1.39
Less Distributions From:
Net investment income		(0.17	)		(0.85	)		(0.40	)		(0.36	)		(0.36	)		(0.37	)
Capital gains		(0.01	)		(0.40	)		(2.15	)		(1.67	)		(2.32	)		(0.67	)
Total distributions		(0.18	)		(1.25	)		(2.55	)		(2.03	)		(2.68	)		(1.04	)
Net increase (decrease) in net asset value		0.29			(0.57	)		(2.01	)		(3.54	)		0.12			0.35
Net Asset Value at end of period	$	13.56		$	13.27		$	13.84		$	15.85		$	19.39		$	19.27
Total Return (%)2		3.58	3		4.98			3.51			(7.87	)		14.64			7.50
Net Assets at end of period (in 000’s)	$	17,911		$	19,171		$	21,959		$	25,053		$	29,739		$	29,102
Ratios of expenses to average net assets (%)		0.52	4		0.52			0.79			0.98			0.97			0.97
Ratio of net investment income to average net assets (%)		4.11	4		5.98			2.46			1.93			1.39			1.79
Portfolio turnover (%)5		16	3		11			118			32			34			31

¹Per share amounts have been calculated using the average shares method. 

²These returns are after all charges at the mutual fund level have been subtracted. These returns are higher than the returns at the separate account level because charges made at the separate account level have not been subtracted. Total returns are not annualized for periods less than one year. 

³Not annualized. 

⁴Annualized. 

⁵Portfolio turnover is calculated at the fund level and represents the entire fiscal year or period. 

See accompanying Notes to Financial Statements.

29

Ultra Series Fund | June 30, 2025

Financial Highlights for a Share of Beneficial Interest Outstanding - continued

CORE BOND FUND

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended
	6/30/25			2024			2023			2022			2021			2020
CLASS I
Net Asset Value at beginning of period	$	8.23		$	8.41		$	8.20		$	9.74		$	10.30		$	9.89
Income from Investment Operations:
Net investment income		0.16	1		0.30	1		0.26			0.23			0.20			0.26
Net realized and unrealized gain (loss) on investments		0.15			(0.16	)		0.23			(1.50	)		(0.37	)		0.62
Total from investment operations		0.31			0.14			0.49			(1.27	)		(0.17	)		0.88
Less Distributions From:
Net investment income		(0.03	)		(0.32	)		(0.28	)		(0.23	)		(0.23	)		(0.28	)
Capital gains		–			–			–			(0.04	)		(0.16	)		(0.19	)
Total distributions		(0.03	)		(0.32	)		(0.28	)		(0.27	)		(0.39	)		(0.47	)
Net increase (decrease) in net asset value		0.28			(0.18	)		0.21			(1.54	)		(0.56	)		0.41
Net Asset Value at end of period	$	8.51		$	8.23		$	8.41		$	8.20		$	9.74		$	10.30
Total Return (%)2		3.85	3		1.52			6.16			(13.17	)		(1.58	)		8.97
Ratios/Supplemental Data:
Net Assets at end of period (in 000’s)	$	42,454		$	53,343		$	61,642		$	67,311		$	85,758		$	92,471
Ratios of expenses to average net assets (%)		0.58	4		0.57			0.57			0.58			0.57			0.57
Ratio of net investment income to average net assets (%)		3.73	4		3.55			3.18			2.40			1.97			2.23
Portfolio turnover (%)5		8	3		16			25			27			34			44

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended
	6/30/25			2024			2023			2022			2021			2020
CLASS II
Net Asset Value at beginning of period	$	8.17		$	8.36		$	8.15		$	9.69		$	10.25		$	9.84
Income from Investment Operations:
Net investment income		0.15	1		0.28	1		0.24			0.12			0.07			0.11
Net realized and unrealized gain (loss) on investments		0.15			(0.17	)		0.23			(1.41	)		(0.25	)		0.74
Total from investment operations		0.30			0.11			0.47			(1.29	)		(0.18	)		0.85
Less Distributions From:
Net investment income		(0.02	)		(0.30	)		(0.26	)		(0.21	)		(0.22	)		(0.25	)
Capital gains		–			–			–			(0.04	)		(0.16	)		(0.19	)
Total distributions		(0.02	)		(0.30	)		(0.26	)		(0.25	)		(0.38	)		(0.44	)
Net increase (decrease) in net asset value		0.28			(0.19	)		0.21			(1.54	)		(0.56	)		0.41
Net Asset Value at end of period	$	8.45		$	8.17		$	8.36		$	8.15		$	9.69		$	10.25
Total Return (%)2		3.73	3		1.27			5.89			(13.38	)		(1.83	)		8.70
Ratios/Supplemental Data:
Net Assets at end of period (in 000’s)	$	11,301		$	11,922		$	13,329		$	15,043		$	19,379		$	23,721
Ratios of expenses to average net assets (%)		0.83	4		0.82			0.82			0.83			0.82			0.82
Ratio of net investment income to average net assets (%)		3.48	4		3.30			2.93			2.15			1.72			1.98
Portfolio turnover (%)5		8	3		16			25			27			34			44

¹Per share amounts have been calculated using the average shares method. 

²These returns are after all charges at the mutual fund level have been subtracted. These returns are higher than the returns at the separate account level because charges made at the separate account level have not been subtracted. Total returns are not annualized for periods less than one year. 

³Not annualized. 

⁴Annualized. 

⁵Portfolio turnover is calculated at the fund level and represents the entire fiscal year or period.

See accompanying Notes to Financial Statements.

30

Ultra Series Fund | June 30, 2025

Financial Highlights for a Share of Beneficial Interest Outstanding - continued

LARGE CAP VALUE FUND

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended
	6/30/25			2024			2023			2022			2021			2020
CLASS I
Net Asset Value at beginning of period	$	23.37		$	22.77		$	23.35		$	27.33		$	23.34		$	25.08
Income from Investment Operations:
Net investment income		0.24	1		0.53	1		0.55			0.63			0.49			0.40
Net realized and unrealized gain (loss) on investments		0.82			1.27			0.03			(1.96	)		4.71			(1.46	)
Total from investment operations		1.06			1.80			0.58			(1.33	)		5.20			(1.06	)
Less Distributions From:
Net investment income		(0.06	)		(0.54	)		(0.58	)		(0.61	)		(0.49	)		(0.38	)
Capital gains		(0.06	)		(0.66	)		(0.58	)		(2.04	)		(0.72	)		(0.30	)
Total distributions		(0.12	)		(1.20	)		(1.16	)		(2.65	)		(1.21	)		(0.68	)
Net increase (decrease) in net asset value		0.94			0.60			(0.58	)		(3.98	)		3.99			(1.74	)
Net Asset Value at end of period	$	24.31		$	23.37		$	22.77		$	23.35		$	27.33		$	23.34
Total Return (%)2		4.55	3		8.02			2.56			(4.91	)		22.36			(3.99	)
Ratios/Supplemental Data:
Net Assets at end of period (in 000’s)	$	163,230		$	176,707		$	185,880		$	202,492		$	239,621		$	220,518
Ratios of expenses to average net assets (%)		0.63	4		0.63			0.62			0.63			0.62			0.62
Ratio of net investment income to average net assets (%)		2.02	4		2.25			2.30			2.33			1.78			1.74
Portfolio turnover (%)5		7	3		20			28			29			32			87

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended
	6/30/25			2024			2023			2022			2021			2020
CLASS II
Net Asset Value at beginning of period	$	22.89		$	22.33		$	22.91		$	26.87		$	22.99		$	24.72
Income from Investment Operations:
Net investment income		0.20	1		0.46	1		0.37			0.42			0.24			0.23
Net realized and unrealized gain (loss) on investments		0.81			1.24			0.15			(1.80	)		4.81			(1.33	)
Total from investment operations		1.01			1.70			0.52			(1.38	)		5.05			(1.10	)
Less Distributions From:
Net investment income		(0.03	)		(0.48	)		(0.52	)		(0.54	)		(0.45	)		(0.33	)
Capital gains		(0.06	)		(0.66	)		(0.58	)		(2.04	)		(0.72	)		(0.30	)
Total distributions		(0.09	)		(1.14	)		(1.10	)		(2.58	)		(1.17	)		(0.63	)
Net increase (decrease) in net asset value		0.92			0.56			(0.58	)		(3.96	)		3.88			(1.73	)
Net Asset Value at end of period	$	23.81		$	22.89		$	22.33		$	22.91		$	26.87		$	22.99
Total Return (%)2		4.42	3		7.75			2.31			(5.14	)		22.05			(4.23	)
Ratios/Supplemental Data:
Net Assets at end of period (in 000’s)	$	1,567		$	1,823		$	2,010		$	2,296		$	3,128		$	3,388
Ratios of expenses to average net assets (%)		0.88	4		0.88			0.87			0.87			0.87			0.87
Ratio of net investment income to average net assets (%)		1.77	4		2.00			2.04			2.06			1.52			1.48
Portfolio turnover (%)5		7	3		20			28			29			32			87

¹Per share amounts have been calculated using the average shares method. 

²These returns are after all charges at the mutual fund level have been subtracted. These returns are higher than the returns at the separate account level because charges made at the separate account level have not been subtracted. Total returns are not annualized for periods less than one year. 

³Not annualized. 

⁴Annualized. 

⁵Portfolio turnover is calculated at the fund level and represents the entire fiscal year or period.

See accompanying Notes to Financial Statements.

31

Ultra Series Fund | June 30, 2025

Financial Highlights for a Share of Beneficial Interest Outstanding - continued

LARGE CAP GROWTH FUND

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended
	6/30/25			2024			2023			2022			2021			2020
CLASS I
Net Asset Value at beginning of period	$	23.04		$	21.63		$	18.79		$	23.42		$	21.11		$	20.17
Income from Investment Operations:
Net investment income		0.04	1		0.15	1		0.07			0.07			0.10			0.09
Net realized and unrealized gain (loss) on investments		0.44			3.37			4.84			(3.21	)		4.68			2.61
Total from investment operations		0.48			3.52			4.91			(3.14	)		4.78			2.70
Less Distributions From:
Net investment income		(0.02	)		(0.15	)		(0.07	)		(0.08	)		(0.08	)		(0.09	)
Capital gains		(0.19	)		(1.96	)		(2.00	)		(1.41	)		(2.39	)		(1.67	)
Total distributions		(0.21	)		(2.11	)		(2.07	)		(1.49	)		(2.47	)		(1.76	)
Net increase (decrease) in net asset value		0.27			1.41			2.84			(4.63	)		2.31			0.94
Net Asset Value at end of period	$	23.31		$	23.04		$	21.63		$	18.79		$	23.42		$	21.11
Total Return (%)2		2.07	3		16.41			26.38			(13.45	)		22.96			13.94
Ratios/Supplemental Data:
Net Assets at end of period (in 000’s)	$	172,825		$	191,639		$	189,065		$	166,176		$	213,648		$	198,560
Ratios of expenses to average net assets (%)		0.83	4		0.83			0.82			0.83			0.82			0.82
Ratio of net investment income to average net assets (%)		0.30	4		0.63			0.36			0.30			0.40			0.43
Portfolio turnover (%)5		15	3		9			13			12			16			29

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended
	6/30/25			2024			2023			2022			2021			2020
CLASS II
Net Asset Value at beginning of period	$	22.12		$	20.86		$	18.19		$	22.73		$	20.57		$	19.71
Income from Investment Operations:
Net investment income		0.00	1,6		0.08	1		(0.09	)		(0.05	)		(0.04	)		(0.01	)
Net realized and unrealized gain (loss) on investments		0.43			3.25			4.80			(3.05	)		4.64			2.59
Total from investment operations		0.43			3.33			4.71			(3.10	)		4.60			2.58
Less Distributions From:
Net investment income		-			(0.11	)		(0.04	)		(0.03	)		(0.05	)		(0.05	)
Capital gains		(0.19	)		(1.96	)		(2.00	)		(1.41	)		(2.39	)		(1.67	)
Total distributions		(0.19	)		(2.07	)		(2.04	)		(1.44	)		(2.44	)		(1.72	)
Net increase (decrease) in net asset value		0.24			1.26			2.67			(4.54	)		2.16			0.86
Net Asset Value at end of period	$	22.36		$	22.12		$	20.86		$	18.19		$	22.73		$	20.57
Total Return (%)2		1.94	3		16.12			26.07			(13.67	)		22.66			13.65
Ratios/Supplemental Data:
Net Assets at end of period (in 000’s)	$	7,935		$	8,703		$	9,811		$	10,324		$	14,667		$	15,900
Ratios of expenses to average net assets (%)		1.08	4		1.08			1.07			1.08			1.07			1.07
Ratio of net investment income to average net assets (%)		1.08	4		0.36			0.09			0.04			0.17			0.19
Portfolio turnover (%)5		15	3		9			13			12			16			29

¹Per share amounts have been calculated using the average shares method. 

²These returns are after all charges at the mutual fund level have been subtracted. These returns are higher than the returns at the separate account level because charges made at the separate account level have not been subtracted. Total returns are not annualized for periods less than one year. 

³Not annualized. 

⁴Annualized. 

⁵Portfolio turnover is calculated at the fund level and represents the entire fiscal year or period. 

⁶Amounts represent less than $ 0.005 per share.

See accompanying Notes to Financial Statements.

32

Ultra Series Fund | June 30, 2025

Financial Highlights for a Share of Beneficial Interest Outstanding - continued

MID CAP FUND

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended
	6/30/25			2024			2023			2022			2021			2020
CLASS I
Net Asset Value at beginning of period	$	17.02		$	18.47		$	15.79		$	19.99		$	17.97		$	18.38
Income from Investment Operations:
Net investment income income		(0.00	)1,2		0.13	2		0.02			(0.02	)		0.01			(0.01	)
Net realized and unrealized gain (loss) on investments		0.09			1.82			4.18			(2.61	)		4.62			1.66
Total from investment operations		0.09			1.95			4.20			(2.63	)		4.63			1.65
Less Distributions From:
Net investment income		(0.01	)		(0.13	)		(0.03	)		–			–			–
Capital gains		(0.84	)		(3.27	)		(1.49	)		(1.57	)		(2.61	)		(2.06	)
Total distributions		(0.85	)		(3.40	)		(1.52	)		(1.57	)		(2.61	)		(2.06	)
Net increase (decrease) in net asset value		(0.76	)		(1.45	)		2.68			(4.20	)		2.02			(0.41	)
Net Asset Value at end of period	$	16.26		$	17.02		$	18.47		$	15.79		$	19.99		$	17.97
Total Return (%)3		0.59	4		10.84			26.85			(13.17	)		26.39			9.69
Ratios/Supplemental Data:
Net Assets at end of period (in 000’s)	$	118,636		$	138,093		$	149,182		$	133,928		$	176,437		$	164,068
Ratios of expenses to average net assets (%)		0.93	5		0.92			0.92			0.93			0.92			0.92
Ratio of net investment income to average net assets (%)		0.07	5		0.66			0.08			(0.15	)		0.06			(0.07	)
Portfolio turnover (%)6		11	4		15			13			17			25			24

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended
	6/30/25			2024			2023			2022			2021			2020
CLASS II
Net Asset Value at beginning of period	$	15.76		$	17.35		$	14.92		$	19.04		$	17.26		$	17.77
Income from Investment Operations:
Net investment income		(0.01	)2		0.07	2		(0.17	)		(0.14	)		(0.14	)		(0.10	)
Net realized and unrealized gain (loss) on investments		0.07			1.71			4.09			(2.41	)		4.53			1.65
Total from investment operations		0.06			1.78			3.92			(2.55	)		4.39			1.55
Less Distributions From:
Net investment income		–			(0.10	)		–			–			–			–
Capital gains		(0.84	)		(3.27	)		(1.49	)		(1.57	)		(2.61	)		(2.06	)
Total distributions		(0.84	)		(3.37	)		(1.49	)		(1.57	)		(2.61	)		(2.06	)
Net increase (decrease) in net asset value		(0.78	)		(1.59	)		2.43			(4.12	)		1.78			(0.51	)
Net Asset Value at end of period	$	14.98		$	15.76		$	17.35		$	14.92		$	19.04		$	17.26
Total Return (%)3		0.46	4		10.57			26.53			(13.39	)		26.08			9.41
Ratios/Supplemental Data:
Net Assets at end of period (in 000’s)	$	3,503		$	3,830		$	4,578		$	4,595		$	6,487		$	7,069
Ratios of expenses to average net assets (%)		1.18	5		1.17			1.17			1.18			1.17			1.17
Ratio of net investment income to average net assets (%)		(0.18	)5		0.39			(0.18	)		(0.41	)		(0.17	)		(0.31	)
Portfolio turnover (%)6		11	4		15			13			17			25			24

¹Amounts represent less than $ (0.005) per share. 

²Per share amounts have been calculated using the average shares method. 

³These returns are after all charges at the mutual fund level have been subtracted. These returns are higher than the returns at the separate account level because charges made at the separate account level have not been subtracted. Total returns are not annualized for periods less than one year. 

⁴Not annualized. 

⁵Annualized. 

⁶Portfolio turnover is calculated at the fund level and represents the entire fiscal year or period.

See accompanying Notes to Financial Statements.

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Financial Highlights for a Share of Beneficial Interest Outstanding - continued

MADISON TARGET RETIREMENT 2020 FUND

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended 6/30/25			2024			2023			2022			2021			2020
Net Asset Value at beginning of period	$	6.40		$	6.41		$	6.45		$	7.60		$	7.87		$	7.83
Income from Investment Operations:
Net investment income		0.10	1		0.23	1		0.24			0.17			0.13			0.09
Net realized and unrealized gain (loss) on investments		0.21			(0.01	)		0.03			(1.15	)		(0.02	)		0.60
Total from investment operations		0.31			0.22			0.27			(0.98	)		0.11			0.69
Less Distributions From:
Net investment income		(0.03	)		(0.23	)		(0.31	)		(0.11	)		(0.10	)		(0.13	)
Capital gains		–			–			–			(0.06	)		(0.28	)		(0.52	)
Total distributions		(0.03	)		(0.23	)		(0.31	)		(0.17	)		(0.38	)		(0.65	)
Net increase (decrease) in net asset value		0.28			(0.01	)		(0.04	)		(1.15	)		(0.27	)		0.04
Net Asset Value at end of period	$	6.68		$	6.40		$	6.41		$	6.45		$	7.60		$	7.87
Total Return (%)2		4.81	3		3.48			4.17			(13.00	)		1.45			8.80
Ratios/Supplemental Data:
Net Assets at end of period (in 000‘s)	$	10,973		$	13,715		$	15,410		$	18,687		$	27,014		$	35,685
Ratios of expenses to average net assets (%)		0.31	4		0.31			0.30			0.31			0.31			0.30
Ratio of net investment income to average net assets (%)		2.97	4		3.46			3.16			2.17			1.54			1.14
Portfolio turnover (%)5		9	3		39			231			305			210			318

¹Per share amounts have been calculated using the average shares method.

²These returns are after all charges at the mutual fund level have been subtracted. These returns are higher than the returns at the separate account level because charges made at the separate account level have not been subtracted. Total returns are not annualized for periods less than one year. 

³Not annualized. 

⁴Annualized. 

⁵Portfolio turnover is calculated at the fund level and represents the entire fiscal year or period.

See accompanying Notes to Financial Statements. 

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MADISON TARGET RETIREMENT 2030 FUND 

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended 6/30/25			2024			2023			2022			2021			2020
Net Asset Value at beginning of period	$	7.19		$	7.01		$	6.95		$	8.15		$	8.18		$	7.89
Income from Investment Operations:
Net investment income		0.10	1		0.22	1		0.22			0.19			0.29			0.09
Net realized and unrealized gain (loss) on investments		0.27			0.17			0.17			(1.14	)		0.29			0.82
Total from investment operations		0.37			0.39			0.39			(0.95	)		0.58			0.91
Less Distributions From:
Net investment income		(0.03	)		(0.21	)		(0.32	)		(0.18	)		(0.20	)		(0.12	)
Capital gains		–			–			–			(0.07	)		(0.41	)		(0.50	)
Return of Capital		–			–			(0.01	)		–			–			–
Total distributions		(0.03	)		(0.21	)		(0.33	)		(0.25	)		(0.61	)		(0.62	)
Net increase (decrease) in net asset value		0.34			0.18			0.06			(1.20	)		(0.03	)		0.29
Net Asset Value at end of period	$	7.53		$	7.19		$	7.01		$	6.95		$	8.15		$	8.18
Total Return (%)2		5.14	3		5.47			5.72			(11.79	)		7.20			11.77
Ratios/Supplemental Data:
Net Assets at end of period (in 000‘s)	$	50,934		$	51,649		$	55,775		$	56,944		$	71,328		$	70,125
Ratios of expenses to average net assets (%)		0.31	4		0.31			0.30			0.31			0.31			0.30
Ratio of net investment income to average net assets (%)		2.62	4		2.96			3.03			2.38			3.40			1.09
Portfolio turnover (%)5		13	3		38			220			303			215			372

¹Per share amounts have been calculated using the average shares method.

²These returns are after all charges at the mutual fund level have been subtracted. These returns are higher than the returns at the separate account level because charges made at the separate account level have not been subtracted. Total returns are not annualized for periods less than one year.

³Not annualized. 

⁴Annualized. 

⁵Portfolio turnover is calculated at the fund level and represents the entire fiscal year or period.

See accompanying Notes to Financial Statements.

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Ultra Series Fund | June 30, 2025

Financial Highlights for a Share of Beneficial Interest Outstanding - continued

MADISON TARGET RETIREMENT 2040 FUND

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended 6/30/25			2024			2023			2022			2021			2020
Net Asset Value at beginning of period	$	6.81		$	6.46		$	6.33		$	7.49		$	7.52		$	7.21
Income from Investment Operations:
Net investment income		0.08	1		0.17	1		0.19			0.18			0.31			0.08
Net realized and unrealized gain (loss) on investments		0.31			0.33			0.23			(1.01	)		0.36			0.81
Total from investment operations		0.39			0.50			0.42			(0.83	)		0.67			0.89
Less Distributions From:
Net investment income		(0.02	)		(0.15	)		(0.27	)		(0.17	)		(0.21	)		(0.10	)
Capital gains		–			–			(0.00	)2		(0.16	)		(0.49	)		(0.48	)
Return of Capital		–			–			(0.02	)		–			–			–
Total distributions		(0.02	)		(0.15	)		(0.29	)		(0.33	)		(0.70	)		(0.58	)
Net increase (decrease) in net asset value		0.37			0.35			0.13			(1.16	)		(0.03	)		0.31
Net Asset Value at end of period	$	7.18		$	6.81		$	6.46		$	6.33		$	7.49		$	7.52
Total Return (%)3		5.66	4		7.78			6.70			(11.35	)		8.91			12.51
Ratios/Supplemental Data:
Net Assets at end of period (in 000‘s)	$	42,381		$	41,180		$	38,064		$	36,024		$	40,984		$	41,990
Ratios of expenses to average net assets (%)		0.31	5		0.31			0.30			0.31			0.31			0.30
Ratio of net investment income to average net assets (%)		2.18	5		2.50			2.84			2.57			3.71			1.08
Portfolio turnover (%)6		18	4		43			210			309			209			367

¹Per share amounts have been calculated using the average shares method. 

²Amounts represent less than $ (0.005) per share. 

³These returns are after all charges at the mutual fund level have been subtracted. These returns are higher than the returns at the separate account level because charges made at the separate account level have not been subtracted. Total returns are not annualized for periods less than one year. 

⁴Not annualized. 

⁵Annualized. 

⁶Portfolio turnover is calculated at the fund level and represents the entire fiscal year or period.

See accompanying Notes to Financial Statements.

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Ultra Series Fund | June 30, 2025

Financial Highlights for a Share of Beneficial Interest Outstanding - concluded

MADISON TARGET RETIREMENT 2050 FUND

	(unaudited)
	Six-Months			Year Ended December 31,
	Ended 6/30/25			2024			2023			2022			2021			2020
Net Asset Value at beginning of period	$	12.11		$	11.32		$	11.01		$	13.21		$	13.00		$	12.37
Income from Investment Operations:
Net investment income		0.12	1		0.27	1		0.29			0.33			0.57			0.13
Net realized and unrealized gain (loss) on investments		0.61			0.75			0.53			(1.76	)		0.74			1.43
Total from investment operations		0.73			1.02			0.82			(1.43	)		1.31			1.56
Less Distributions From:
Net investment income		(0.04	)		(0.23	)		(0.48	)		(0.33	)		(0.38	)		(0.18	)
Capital gains		–			–			(0.02	)		(0.44	)		(0.72	)		(0.75	)
Return of Capital		–			–			(0.01	)		–			–			–
Total distributions		(0.04	)		(0.23	)		(0.51	)		(0.77	)		(1.10	)		(0.93	)
Net increase (decrease) in net asset value		0.69			0.79			0.31			(2.20	)		0.21			0.63
Net Asset Value at end of period	$	12.80		$	12.11		$	11.32		$	11.01		$	13.21		$	13.00
Total Return (%)2		5.96	3		9.04			7.60			(11.04	)		10.22			12.80
Ratios/Supplemental Data:
Net Assets at end of period (in 000‘s)	$	36,499		$	35,846		$	32,365		$	28,467		$	34,283		$	30,437
Ratios of expenses to average net assets (%)		0.31	4		0.31			0.30			0.31			0.30			0.30
Ratio of net investment income to average net assets (%)		1.98	4		2.25			2.71			2.63			4.34			1.07
Portfolio turnover (%)5		19	3		37			226			329			228			390

¹Per share amounts have been calculated using the average shares method.

²These returns are after all charges at the mutual fund level have been subtracted. These returns are higher than the returns at the separate account level because charges made at the separate account level have not been subtracted. Total returns are not annualized for periods less than one year. 

³Not annualized. 

⁴Annualized. 

⁵Portfolio turnover is calculated at the fund level and represents the entire fiscal year or period.

See accompanying Notes to Financial Statements.

37

Ultra Series Fund | June 30, 2025

Notes to Financial Statements (unaudited)

1. ORGANIZATION

The Ultra Series Fund (the “Trust”), a Massachusetts business trust, is registered under the Investment Company Act of 1940, as amended (the “1940 Act”), as a diversified, open-end management investment company. The Trust is a series trust with 12 investment portfolios (individually, a “Fund,” and collectively, the “Funds”), each with different investment objectives and policies. The Funds are the Core Bond Fund, Large Cap Value Fund, Large Cap Growth Fund, and Mid Cap Fund (collectively, the “Core Funds”), the Conservative Allocation Fund, Moderate Allocation Fund, Aggressive Allocation Fund and Diversified Income Fund (collectively, the “Target Allocation Funds”) and the Madison Target Retirement 2020 Fund, Madison Target Retirement 2030 Fund, Madison Target Retirement 2040 Fund, and Madison Target Retirement 2050 Fund, (collectively, the “Target Date Funds”). Madison Asset Management, LLC (the “Investment Adviser” or “Madison”) serves as the Funds’ investment adviser.

The Declaration of Trust permits the Board of Trustees to issue an unlimited number of full and fractional shares of the Trust without par value. All Funds, except the Target Date Funds, offer Class I and II shares. The Target Date Funds only offer Class I shares. Each class of shares represents an interest in the assets of the respective Fund and has identical voting, dividend, liquidation and other rights, except that each class of shares bears its own distribution fee, if any, and its proportional share of Fund level expenses, and has exclusive voting rights on matters pertaining to Rule 12b-1 under the 1940 Act as it relates to that class and other class specific matters. Shares are offered to separate accounts (the “Accounts”) of TruStage Financial Group, Inc. (“TruStage”) and to qualified pension and retirement plans of TruStage. The Trust may, in the future, offer other share classes to separate accounts of insurance companies and to qualified pension and retirement plans that are not affiliated with TruStage. The Trust does not offer shares directly to the general public.

2. SIGNIFICANT ACCOUNTING POLICIES

The preparation of financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of income and expenses during the reported period. Actual results could differ from those estimates.

The Funds are investment companies that apply the accounting and reporting guidance in the Financial Accounting Standards Board (FASB) Accounting Standards Codification Topic 946 Financial Services—Investment Companies (ASC 946).

The following is a summary of significant accounting policies consistently followed by each Fund in the preparation of its financial statements.

Portfolio Valuation: Equity securities, including closed-end investment companies, American Depositary Receipts (“ADRs”),Global Depositary Receipts (“GDRs”) and exchange-traded Funds (“ETFs”) listed on any U.S. or foreign stock exchange or quoted on the National Association of Securities Dealers Automated Quotation System (“NASDAQ’’) are valued at the last quoted sale price or official closing price on that exchange or NASDAQ on the valuation day (provided that, for securities traded on NASDAQ, the Funds utilize the NASDAQ Official Closing Price (“NOCP”). If no sale occurs, equities traded on a U.S. exchange, foreign exchange or on NASDAQ are valued at the bid price. Debt securities (other than short-term obligations) purchased with a remaining maturity of 61 days or more are valued on the basis of last available bid prices or current market quotations provided by dealers or pricing services approved by the Trust. In determining the value of a particular investment, pricing services may use certain information with respect to transactions in such investments, quotations from dealers, pricing

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Ultra Series Fund | June 30, 2025

Notes to Financial Statements (unaudited) - continued

matrixes, market transactions in comparable investments, various relationships observed in the market between investments and calculated yield measures based on valuation technology commonly employed in the market for such investments.

Municipal debt securities are traded via a network among dealers and brokers that connect buyers and sellers. They are valued on the basis of last available bid prices or current market quotations provided by dealers or pricing services approved by the Trust. There may be little trading in the secondary market for the particular bonds and other debt securities, making them more difficult to value or sell. Asset-backed and mortgage-backed securities are valued by independent pricing services using models that consider estimated cash flows of each tranche of the security, establish a benchmark yield and develop an estimated tranche specific spread to the benchmark yield based on the unique attributes of the tranche.

Investments in shares of open-end mutual funds, including money market funds, are valued at their daily net asset value (“NAV”) which is calculated as of the close of regular trading on the New York Stock Exchange (the “NYSE”) usually 4:00 p.m. Eastern Standard Time on each day on which the NYSE is open for business. NAV per share is determined by dividing each Fund’s total net assets by the number of shares of such Fund outstanding at the time of calculation. Because the assets of each Target Allocation Fund and each Target Date Fund consist primarily of shares of other registered investment companies (the “Underlying Funds”), the NAV of each Fund is determined based on the NAVs of the Underlying Funds. Total net assets are determined by adding the total current value of portfolio securities, cash, receivables, and other assets and subtracting liabilities. Short-term instruments having maturities of 60 days or less are valued on an amortized cost basis, which approximates fair value.

Over-the-counter securities not listed or traded on NASDAQ are valued at the last sale price on the valuation day. If no sale occurs on the valuation day, an over-the-counter security is valued at the last bid price. Exchange-traded options are valued at the mean of the best bid and ask prices across all option exchanges. Over-the-counter options are valued based upon prices provided by market makers in such securities or dealers in such currencies. Financial futures contracts generally are valued at the settlement price established by the exchange(s) on which the contracts are primarily traded. Overnight repurchase agreements are valued at cost, and term repurchase agreements (i.e., those whose maturity exceeds seven days), swaps, caps, collars and floors, if any, are valued at the average of the closing bids obtained daily from at least one dealer.

Through the end of this reporting period, the value of all assets and liabilities expressed in foreign currencies was converted into U.S. dollar values using the then-current exchange rate at the close of regular trading on the NYSE.

All other securities for which either quotations are not readily available, no other sales have occurred, or in the Investment Adviser’s opinion, do not reflect the current fair value, are appraised at their fair values as determined in good faith by the Investment Adviser’s Pricing Committee (the “Committee”) and under the general supervision of the Board of Trustees. When fair value pricing of securities is employed, the prices of securities used by the Funds to calculate NAV may differ from market quotations or NOCP. Because the Target Allocation Funds and Target Date Funds primarily invest in Underlying Funds, government securities and short-term paper, it is not anticipated that the Investment Adviser will need to “fair value” any of the investments of these Funds. However, an Underlying Fund may need to “fair value” one or more of its investments, which may, in turn, require a Target Allocation Fund or Target Date Fund to do the same because of delays in obtaining the Underlying Fund’s NAV.

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Ultra Series Fund | June 30, 2025

Notes to Financial Statements (unaudited) - continued

Rule 2a-5 under the 1940 Act (the “Valuation Rule”) establishes requirements for determining fair value in good faith , including related oversight and reporting requirements. The Valuation Rule also defines when market quotations are “readily available,” which is the threshold for determining whether a Fund must fair value a security. Among other things, the Valuation Rule permits a board of trustees of a Fund to designate a Fund’s investment adviser as valuation designee to perform a Fund’s fair value determinations subject to board oversight and certain reporting and other requirements intended to ensure that the board receives the information it needs to oversee a Fund’s investment adviser fair value determinations. The Board has designated the Funds’ Investment Adviser as Valuation Designee and the Valuation Designee has delegated valuation decisions to the Committee.

A Fund’s investments will be valued at fair value if, in the judgment of the Committee, an event impacting the value of an investment occurred between the closing time of a security’s primary market or exchange (for example, a foreign exchange or market) and the time the Fund’s share price is calculated as of the close of regular trading on the NYSE. Significant events may include, but are not limited to, the following: (1) significant fluctuations in domestic markets, foreign markets or foreign currencies; (2) occurrences not directly tied to the securities markets such as natural disasters, armed conflicts or significant government actions; and (3) major announcements affecting a single issuer or an entire market or market sector. Fixed income securities either newly issued or not being priced for various reasons by one of our approved pricing sources may also be fair valued. In responding to a significant event, the Committee would determine the fair value of affected securities considering factors including, but not limited to: fundamental analytical data relating to the investment; the nature and duration of any restrictions on the disposition of the investment; and the forces influencing the market(s) in which the investment is purchased or sold.

In addition to the fair value decisions made by the Committee noted above, the Committee also engages an independent fair valuation service to adjust the valuations of foreign equity securities based on specific market-movement parameters established by the Committee and approved by the Board of Trustees. Such adjustments to the valuation of foreign securities are applied automatically upon market close if the parameters established are exceeded. A foreign security is also automatically fair valued if the exchange it is traded on is on holiday.

Segment Reporting: The Funds have adopted FASB Accounting Standards Update 2023-07, Segment Reporting (Topic 280) - Improvements to Reportable Segment Disclosures (“ASU 2023-07”). Adoption of the new standard impacted financial statement disclosures only and did not affect the Fund’s financial position or the results of its operations. An operating segment is defined in Topic 280 as a component of a public entity that engages in business activities from which it may recognize revenues and incur expenses, has operating results that are regularly reviewed by the public entity’s chief operating decision maker (CODM) to make decisions about resources to be allocated to the segment and assess its performance, and has discrete financial information available. The Management Committee of the Trust’s Investment Adviser acts as the CODM. Each Fund within the Trust represents a single operating segment, as the CODM monitors the operating results of each Fund as a whole and the Fund’s long-term strategic asset allocation is pre-determined in accordance with the terms of its prospectus, based on a defined investment strategy which is executed by the Fund’s portfolio managers as a team. The financial information in the form of a Fund’s total returns, expense ratios, changes in net assets resulting from operations, subscriptions and redemptions and profitability to the Investment Adviser, which are used by the CODM to assess the segment’s performance versus the Fund’s comparative benchmarks and peers to make resource allocation decisions for the Fund’s single segment, is consistent with that presented within the Fund’s financial statements.

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Ultra Series Fund | June 30, 2025

Notes to Financial Statements (unaudited) - continued

Segment assets are reflected on the accompanying statement of assets and liabilities as “total assets” and significant segment expenses are listed on the accompanying statement of operations.

Security Transactions and Investment Income: Security transactions are accounted for on a trade date basis. Net realized gains or losses on sales are determined by the identified cost method. Net realized gain on investments in the Statements of Operations also includes realized gain distributions received from the underlying exchange-listed funds. Distributions of net realized gains are recorded on the Fund’s ex-distribution date. Dividend income is recorded on ex-dividend date, except that certain dividends from foreign securities may be recorded after the ex-dividend date based on when the Funds are informed of the dividend. Interest income is recorded on an accrual basis and is increased by the accretion of discount and decreased by the amortization of premium. Amortization and accretion are recorded on the effective yield method.

Expenses: Expenses that are directly related to one fund are charged directly to that Fund. Other operating expenses are prorated to the Funds on the basis of relative net assets. Class-specific expenses are borne by that class.

Share Classes: Income and realized and unrealized gains/losses are allocated to the respective classes on the basis of relative net assets.

Repurchase Agreements: Each Fund may engage in repurchase agreements. In a repurchase agreement, a security is purchased for a relatively short period (usually not more than seven days) subject to the obligation to sell it back to the issuer at a fixed time and price plus accrued interest. The Funds will enter into repurchase agreements only with members of the Federal Reserve System, U.S. Central Credit Union and with “primary dealers” in U.S. government securities.

The Trust has established a procedure providing that the securities serving as collateral for each repurchase agreement must be delivered to the Trust’s custodian either physically or in book-entry form and that the collateral must be marked to market daily to ensure that each repurchase agreement is fully collateralized at all times. In the event of bankruptcy or other default by a seller of a repurchase agreement, a Fund could experience one of the following: delays in liquidating the underlying securities during the period in which the Fund seeks to enforce its rights thereto, possible decreased levels of income, declines in value of the underlying securities, or lack of access to income during this period and the expense of enforcing its rights. As of June 30, 2025, none of the Funds held open repurchase agreements.

Foreign Currency Transactions: The Trust’s books and records are maintained in U.S. dollars. Foreign currency-denominated transactions (i.e., fair value of investment securities, assets and liabilities, purchases and sales of investment securities, and income and expenses) are translated into U.S. dollars at the current rate of exchange. The Funds enter into contracts on the trade date to settle any securities transactions denominated in foreign currencies on behalf of the Funds at the spot rate at settlement.

Each Fund may invest in foreign currency transactions. Such funds report certain foreign currency-related transactions as components of realized gains or losses for financial reporting purposes, whereas such components are treated as ordinary income for federal income tax purposes. Realized gains or losses associated with currency transactions are included in the Statements of Operations under the heading “Net realized gain (loss) on investments. As of June 30, 2025, none of the Funds had open foreign currency transactions.

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Notes to Financial Statements (unaudited) - continued

The Funds do not isolate the portion of gains and losses on investments in securities that is due to changes in the foreign exchange rates from that which is due to change in market prices of securities. Such amounts are categorized as gain or loss on investments for financial reporting purposes.

Cash Concentration: At times, the Funds maintain cash balances at financial institutions in excess of federally insured limits. The Funds monitor this credit risk and have not experienced any losses related to this risk.

Illiquid Securities: Each Fund currently limits investments in illiquid investments, as defined by Rule 22e-4 under the 1940 Act, to 15% of net assets at the time of purchase. An illiquid investment is generally defined as a security that a Fund reasonably expects cannot be sold or disposed of in current market conditions in seven calendar days or less without the sale or disposition significantly changing the market value of the security. As of June 30, 2025, there were no illiquid securities held in the Funds.

Delayed Delivery Securities: Each Fund may purchase securities on a when-issued or delayed delivery basis. “When-issued” refers to securities whose terms are available and for which a market exists, but that have not been issued. For when-issued or delayed delivery transactions, no payment is made until delivery date, which is typically longer than the normal course of settlement. When a Fund enters into an agreement to purchase securities on a when-issued or delayed delivery basis, the Fund may segregate cash or other liquid securities, of any type or maturity, equal in value to the Fund’s commitment. Losses may arise due to changes in the fair value of the underlying securities, if the counterparty does not perform under the contract, or if the issuer does not issue the securities due to political, economic or other factors. During the period ended June 30, 2025, none of the Funds had entered into such transactions.

Indemnifications: Under the Funds’ organizational documents, the Funds’ officers and Trustees are indemnified against certain liabilities arising out of the performance of their duties to the Funds. In the normal course of business, the Funds enter into contracts that contain a variety of representations and provide general indemnifications. The Funds’ maximum liability exposure under these arrangements is unknown, as future claims that have not yet occurred may be made against the Funds. However, based on experience, management expects the risk of loss to be remote.

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3. FAIR VALUE MEASUREMENTS

Each Fund has adopted FASB guidance on fair value measurements. Fair value is defined as the price that each Fund would receive upon selling an investment in a timely transaction to an independent buyer in the principal or most advantageous market of the investment. A three-tier hierarchy is used to maximize the use of observable market data “inputs” and minimize the use of unobservable “inputs” and to establish classification of fair value measurements for disclosure purposes. Inputs refer broadly to the assumptions that market participants would use in pricing the asset or liability, including assumptions about risk (for example, the risk inherent in a particular valuation technique used to measure fair value including such a pricing model and/or the risk inherent in the inputs used in the valuation technique). Inputs may be observable or unobservable.

Observable inputs are inputs that reflect the assumptions market participants would use in pricing the asset or liability developed based on market data obtained from sources independent of the reporting entity. Unobservable inputs are inputs that reflect the reporting entity’s own assumptions about the assumptions market participants would use in pricing the asset or liability developed based on the best information available in the circumstances. The three-tier hierarchy of inputs is summarized in the three broad Levels listed below:

• Level 1 - unadjusted quoted prices in active markets for identical investments

• Level 2 - other significant observable inputs (including quoted prices for similar investments, interest rate volatilities, prepayment speeds, credit risk, benchmark yields, transactions, bids, offers, new issues, spreads, and other relationships observed in the markets among comparable securities, underlying equity of the issuer; and proprietary pricing models such as yield measures calculated using factors such as cash flows, financial or collateral performance, and other reference data, etc.)

• Level 3 - significant unobservable inputs (including the Fund’s own assumptions in determining the fair value of investments).

The valuation techniques used by the Funds to measure fair value for the period ended June 30, 2025 maximized the use of observable inputs and minimized the use of unobservable inputs. The Funds utilized the following fair value techniques: multi-dimensional relational pricing model and option adjusted spread pricing; the Funds estimated the price that would have prevailed in a liquid market for an international equity security given information available at the time of valuation. As of June 30, 2025, none of the Funds held securities deemed as a Level 3, and there were no transfers between classification levels.

The following is a summary of the inputs used as of June 30, 2025, in valuing the Funds’ investments carried at fair value (please see the portfolio of Investments for each fund for a listing of all securities within each category):

Fund1	Level 1		Level 2		Level 3		Value at 6/30/25
Conservative Allocation
Exchange Traded Funds	$	22,466,999	$	–	$	–	$	22,466,999
Investment Companies		23,893,867		–		–		23,893,867
Short-Term Investments		1,358,877		–		–		1,358,877
		47,719,743		–		–		47,719,743
Moderate Allocation
Exchange Traded Funds		55,752,216		–		–		55,752,216
Investment Companies		42,959,421		–		–		42,959,421
Short-Term Investments		6,792,233		–		–		6,792,233
		105,503,870		–		–		105,503,870

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Fund1	Level 1		Level 2		Level 3		Value at 6/30/25
Aggressive Allocation
Exchange Traded Funds	$	26,726,229	$	–	$	–	$	26,726,229
Investment Companies		13,159,284		–		–		13,159,284
Short-Term Investments		3,571,889		–		–		3,571,889
		43,457,402		–		–		43,457,402
Diversified Income
Commercial Mortgage-Backed Securities		–		–		–		–
Exchange Traded Funds		143,254,426		–		–		143,254,426
Mortgage Backed Securities		–		16,842		–		16,842
Short-Term Investments		2,004,406		–		–		2,004,406
		145,258,832		16,842		–		145,275,674
Core Bond
Asset Backed Securities		–		650,821		–		650,821
Collateralized Mortgage Obligations		–		3,504,613		–		3,504,613
Commercial Mortgage-Backed Securities		–		411,134		–		411,134
Corporate Notes and Bonds		–		13,797,200		–		13,797,200
Foreign Corporate Bonds		–		1,680,986		–		1,680,986
Mortgage Backed Securities		–		22,127,479		–		22,127,479
U.S. Government and Agency Obligations		–		10,162,561		–		10,162,561
Short-Term Investments		1,299,464		–		–		1,299,464
		1,299,464		52,334,794		–		53,634,258
Large Cap Value
Common Stocks		162,254,429		–		–		162,254,429
Short-Term Investments		2,613,412		–		–		2,613,412
		164,867,841		–		–		164,867,841
Large Cap Growth
Common Stocks		177,084,943		–		–		177,084,943
Short-Term Investments		3,704,865		–		–		3,704,865
		180,789,808		–		–		180,789,808
Mid Cap
Common Stocks		116,638,224		–		–		116,638,224
Short-Term Investments		5,611,413		–		–		5,611,413
		122,249,637		–		–		122,249,637
Madison Target Retirement 2020 Fund	$	10,972,142	$	–	$	–	$	10,972,142
Madison Target Retirement 2030 Fund		50,919,355		–		–		50,919,355
Madison Target Retirement 2040 Fund		42,356,163		–		–		42,356,163
Madison Target Retirement 2050 Fund		36,479,637		–		–		36,479,637

¹ See respective portfolio of Investments for underlying holdings in each Fund. For additional Fund’s information on the Underlying Funds held in the Target Allocation Funds and Target Date Funds including shareholder prospectuses and financial reports, please visit each Underlying fund’s website or visit the Securities and Exchange Commission website at http://www.sec.gov.

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4. ADVISORY, DISTRIBUTION, ADMINISTRATIVE SERVICES AGREEMENTS AND OTHER EXPENSES

Investment Advisory Agreements: For its investment advisory services to the Funds, the Investment Adviser is entitled to receive a fee, which is computed daily and paid monthly, at an annualized percentage rate of the average daily value of the net assets of each Fund as follows as of June 30, 2025:

Fund	Advisory Fee	Fund	Advisory Fee
Conservative Allocation	0.30%	Large Cap Growth	0.80%
Moderate Allocation	0.30%	Mid Cap	0.90%
Aggressive Allocation	0.30%	Madison Target Retirement 2020	0.25%
Diversified Income	0.25%	Madison Target Retirement 2030	0.25%
Core Bond	0.55%	Madison Target Retirement 2040	0.25%
Large Cap Value	0.60%	Madison Target Retirement 2050	0.25%

The Investment Advisory Agreement for the Core Funds and the Target Allocation Funds is structured as a “unitary fee arrangement” and, as such, requires the Investment Adviser to provide or arrange to provide overall management of the Funds, including but not limited to, investment management services, custody, transfer agency, dividend disbursing, legal, accounting and administrative services. The unitary fee arrangement with these Funds does not cover, and therefore these Funds pay directly for, the following fees and expenses: (i) fees and expenses of the Independent Trustees; (ii) fees and expenses of the Trust’s independent registered public accountant; (iii) brokerage commissions and other expenses incurred in the acquisition or disposition of any securities or other investments; (iv) costs of borrowing money, overdrafts (if any) and any potential taxes owed; and (v) extraordinary expenses (including litigation and/or and consulting expenses) as approved by a majority of the Independent Trustees, (these expenses are collectively referred to as “Direct Fund Expenses”).

In contrast, the Investment Advisory Agreement for the Target Date Funds is not structured as a “unitary fee arrangement.” Accordingly, under the Investment Advisory Agreement for these Funds, the Investment Adviser is only responsible for providing investment management services to the Funds. Other services performed by the Investment Adviser for the Target Date Funds are covered under a separate Administrative Services Agreement (discussed below).

Under the Investment Advisory Agreements for the Core Funds, the Allocation Funds, and the Target Date Funds, the Investment Adviser may from time to time, contractually or voluntarily, agree to waive a portion of its management fee and/or reimburse a Fund’s operating expenses to ensure that the Fund’s operating expenses do not exceed certain expense limitations. Any fees waived or reimbursed are not subject to later recoupment by the Investment Adviser. The Investment Adviser may also permanently reduce the amount of the management fee for one or more Funds under such terms as it may determine by written notice thereof to the Trust.

In connection with the most recent approval by the Board of Trustees of the Investment Advisory Agreements, the Investment Adviser contractually agreed to enter into an Operating Expense Limitation Agreement with the Trust, on behalf of the Funds, under which the Investment Adviser agreed to waive its management fees and/ or reimburse expenses of each Fund to the extent necessary to limit each class of each Fund’s total operating expenses (excluding certain expenses described below) to the annual rate set forth in the Funds’ then-currently effective prospectus (i.e., the prospectus dated May 1, 2024, as supplemented). The Operating Expense Limitation Agreement became effective for all Funds on December 1, 2023, and will remain in place until at least November 30, 2025. For the period ended June 30, 2025, the Investment Adviser did not waive any of its management fees and/or reimburse Fund expenses because all Funds operated under the fee cap during the period. Expenses excluded from the fee cap in the Operating Expense Limitation Agreement are as follows:

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Core Funds and Allocation Funds: Excluded expenses are those expenses assumed by the Funds as provided in Section 4(b) of the relevant Investment Advisory Agreement. Such expenses consist of those expenses identified as “Direct Fund Expenses,” above.

Target Date Funds: Excluded expenses consist of the following: any front-end or contingent deferred loads, taxes, leverage/borrowing interest, interest expense, dividends paid on short sales, brokerage commissions, acquired fund fees and expenses, extraordinary expenses such as litigation, and other “Excluded Expenses” (as defined in the Administrative Services Agreement, described below).

Administrative Services Agreement - Target Date Funds: With respect to the Target Date Funds only, in addition to the advisory fee, the Investment Adviser is entitled to receive an administrative services fee pursuant to the terms of a separate Administrative Services Agreement. Under this agreement, the Investment Adviser has agreed to provide or arrange to have a third party provide the Target Date Funds with such services as they may require in the conduct of their business, to the extent that the Investment Adviser, acting as the Funds’ investment adviser, has not undertaken to provide such services. Services to the Target Date Funds under the Administrative Services Agreement include transfer agent services; fund administrator services; fund accountant services; services of the Trust’s independent public accountants; services of legal counsel to the Trust and the Independent Trustees; and such other services necessary to conduct the Funds’ business. In exchange for these services, each Target Date Fund pays the Investment Adviser a fee, which is computed daily and paid monthly, at an annualized rate of 0.05% the average daily value of the net assets of each Target Date Fund. Not included in this fee and, therefore, the responsibility of the Target Date Funds, are the following fees and expenses: (i) any fees and expenses relating to portfolio holdings (e.g., brokerage commissions, interest on loans, etc.); (ii) extraordinary and non-recurring fees and expenses (e.g., costs relating to overdrafts of any line of credit maintained with its custodian or another entity for investment purposes); (iii) the costs associated with investment by the Target Date Funds in other investment companies (i.e., acquired fund fees); and (iv) the compensation of Trust’s Independent Trustees (these expenses are collectively referred to as “Excluded Expenses”).

Other Expenses: Due to the “unitary fee arrangement” in place with respect to the Core Funds and the Target Allocation Funds, and the Administrative Services Agreement arrangement in place with respect to the Target Date Funds, the Core Funds and the Allocation Funds are directly responsible for certain fees and expenses that differ somewhat from the fees and expenses for which the Target Date Funds are directly responsible.

Distribution Agreement: MFD Distributor, LLC (“MFD”) serves as distributor of the Funds. The Trust adopted a distribution and service plan with respect to the Trust’s Class II shares pursuant to Rule 12b-1 under the 1940 Act. Under the plan, the Trust will pay a service fee with regard to Class II shares at an annual rate of 0.25% each Fund’s daily net assets.

MFD may from time to time voluntarily agree to waive a portion of its fees or expenses related to the Funds. For the period ended June 30, 2025, no fees were waived. MFD does not have the right to recoup waived fees.

Officers and Trustees: Certain officers and Trustees of the Trust may also be officers, directors and/or employees of the Adviser or its affiliates. The Trust does not compensate its officers or Trustees who are officers, directors and/ or employees of the Adviser or its affiliates. The Independent Trustees fees are a direct expense of the Funds which is included in the “Trustee fees” line item on the Statements of Operations. The Nominating and Governance Committee of the Board reviews fees paid to Independent Trustees periodically, and may change such fees at any time.

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5. DIVIDENDS FROM NET INCOME AND DISTRIBUTIONS OF CAPITAL GAINS

The Funds declare dividends from net investment income and net realized gains from investment transactions, if any, annually, which are reinvested in additional full and fractional shares of the respective Funds.

Income and capital gain distributions, if any, are determined in accordance with federal income tax regulations, which may differ from accounting principles generally accepted in the United States of America. Taxable distributions from income and realized capital gains of the Funds may differ from book amounts earned during the period due to differences in the timing of capital gains recognition, and due to the reclassification of certain gains or losses from capital to income. Dividends from net investment income are determined on a class level. Capital gains are determined on a Fund level.

6. SECURITIES TRANSACTIONS

For the period ended June 30, 2025, aggregate cost of purchases and proceeds from sales of securities, other than short-term investment, were as follows:

	U.S. Government Securities				Other Investment Securities
Fund	Purchases		Sales		Purchases		Sales
Conservative Allocation	$	–	$	–	$	9,052,410	$	11,807,632
Moderate Allocation		–		–		25,407,832		32,686,190
Aggressive Allocation		–		–		10,438,088		11,438,155
Diversified Income		–		244		23,652,296		30,188,378
Core Bond		3,694,321		7,637,977		1,023,465		7,025,330
Large Cap Value		–		–		12,073,105		31,573,313
Large Cap Growth		–		–		28,465,831		52,234,438
Mid Cap		–		–		14,050,050		33,533,106
Madison Target Retirement 2020		–		–		1,027,884		3,945,705
Madison Target Retirement 2030		–		–		6,496,097		8,809,878
Madison Target Retirement 2040		–		–		7,121,847		7,765,386
Madison Target Retirement 2050		–		–		6,379,285		7,118,037

7. FOREIGN SECURITIES

Each Fund may invest in foreign securities. Foreign securities are defined as securities that are: (i) issued by companies organized outside the U.S. or whose principal operations are outside the U.S., or issued by foreign governments or their agencies or instrumentalities (“foreign issuers”); (ii) principally traded outside of the U.S.; and/or (iii) quoted or denominated in a foreign currency (“non-dollar securities”). Foreign securities include American Depositary Receipts (“ADRs”), European Depositary Receipts (“EDRs”), Global Depositary Receipts (“GDRs”), Swedish Depositary Receipts (“SDRs”) and foreign money market securities. U.S. dollar-denominated securities that are part of the Merrill Lynch U.S. Domestic Master Index are not considered a foreign security.

8. SECURITIES LENDING

The Board of Trustees has authorized the Funds, other than the Target Date Funds, to engage in securities lending with State Street Bank and Trust Company as securities lending agent pursuant to a Securities Lending Authorization Agreement (the “Agreement”) and subject to the Trust’s securities lending policies and procedures. Under the terms of the Agreement, and subject to the policies and procedures, the authorized Funds may lend portfolio securities to qualified borrowers in order to generate additional income, while managing risk associated with the securities lending program. The Agreement requires that loans are collateralized at all times by cash or U.S. government securities, initially equal to at least 102% of the value of domestic securities and 105% of

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non-domestic securities, based upon the prior days market value for securities loaned. The loaned securities and collateral are marked to market daily to maintain collateral at 102% and 105% for non-domestic security of the total loaned portfolio for each broker/borrower. Amounts earned as interest on investments of cash collateral, net of rebates and fees, if any, are included in the Statements of Operations. The primary risk associated with securities lending is loss associated with investment of cash and non-cash collateral. A secondary risk is if the borrower defaults on its obligation to return the securities loaned because of insolvency or other reasons. The Funds could experience delays and costs in recovering securities loaned or in gaining access to the collateral. Under the Agreement, the securities lending agent has provided a limited indemnification in the event of a borrower default. The Funds do not have a master netting agreement.

As of June 30, 2025, the aggregate fair value of securities on loan for the Trust was $23,159,402. Cash collateral received for such loans are reinvested into the State Street Navigator Securities Lending Government Money Market Portfolio. Non-cash collateral is comprised of U.S.treasuries or other U.S. government securities. See below for fair value on loan and collateral breakout for each Fund and each respective Fund’s portfolio of investments for individual securities identified on loan.

Fund	Market Value		Cash Collateral1		Non-Cash Collateral1
Conservative Allocation	$	1,678,713	$	913,695	$	800,072
Moderate Allocation		3,824,490		3,545,191		355,205
Aggressive Allocation		2,075,446		1,931,648		191,607
Diversified Income		7,115,160		1,088,375		6,218,526
Core Bond		193,305		196,490		–
Large Cap Growth		5,339,463		–		5,447,235
Mid Cap		2,932,825		–		3,030,023

¹Collateral Represents minimum 102% of the value of domestic securities and 105% of non-domestic securities on loan, based upon the prior days market value for securities loaned.

The following table provides increased transparency about the types of collateral pledged for securities lending transactions that are accounted for as secured borrowing. Non-cash collateral is not reflected in the table because the Funds cannot repledge or resell this collateral.

	Remaining Contractual Maturity of the Agreements As of June 30, 2025
	Overnight and Continuous		<30 days		Between 30 & 90 days		>90 days		Total
Securities Lending Transactions1
Conservative Allocation Fund
Common Stocks	$	913,695	$	—	$	—	$	—	$	913,695
Total Borrowings	$	913,695	$	—	$	—	$	—	$	913,695
Gross amount of recognized liabilities for securities lending transactions									$	913,695
Moderate Allocation Fund
Common Stocks	$	3,545,191	$	—	$	—	$	—	$	3,545,191
Total Borrowings	$	3,545,191	$	—	$	—	$	—	$	3,545,191
Gross amount of recognized liabilities for securities lending transactions									$	3,545,191
Aggressive Allocation Fund
Common Stocks	$	1,931,648	$	—	$	—	$	—	$	1,931,648
Total Borrowings	$	1,931,648	$	—	$	—	$	—	$	1,931,648
Gross amount of recognized liabilities for securities lending transactions									$	1,931,648

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	Remaining Contractual Maturity of the Agreements As of June 30, 2025
	Overnight and Continuous		<30 days		Between 30 & 90 days		>90 days		Total
Diversified Income Fund
Common Stocks	$	1,088,375	$	—	$	—	$	—	$	1,088,375
Total Borrowings	$	1,088,375	$	—	$	—	$	—	$	1,088,375
Gross amount of recognized liabilities for securities lending transactions									$	1,088,375
Core Bond Fund
Corporate Bonds	$	196,490	$	—	$	—	$	—	$	196,490
Total Borrowings	$	196,490	$	—	$	—	$	—	$	196,490
Gross amount of recognized liabilities for securities lending transactions									$	196,490

¹ Amounts represent the payable for cash collateral received on securities on loan. This will generally be in the “Overnight and Continuous” column as the securities are typically callable on demand. The payable will be allocated into categories of securities based on the market value of the securities on loan.

9. FEDERAL AND FOREIGN INCOME TAX INFORMATION

It is each Fund’s policy to comply with the requirements of Subchapter M of the Internal Revenue Code of 1986, as amended applicable to regulated investment companies and to distribute all its taxable income to its shareholders and any net realized capital gains at least annually. Accordingly, no provisions for federal income taxes are recorded in the accompanying statements.

The Funds have not recorded any liabilities for material unrecognized tax benefits as of June 30, 2025. It is each Fund’s policy to recognize accrued interest and penalties related to uncertain tax benefits in income taxes, as appropriate. Tax years that remain open to examination by major tax jurisdictions include tax years ended October 31, 2021 through October 31, 2024.

For federal income tax purposes, the Funds listed below have capital loss carryforwards as December 31, 2024 which are available to offset future capital gains, if any, realized through the fiscal year listed:

	No-Expiration Date
Fund	Short-Term		Long-Term
Conservative Allocation	$	4,005,544	$	1,770,530
Core Bond		367,965		5,355,172
Madison Target Retirement 2020		2,176,408		820,842
Madison Target Retirement 2030		2,678,365		1,125,439
Madison Target Retirement 2040		1,390,852		302,228
Madison Target Retirement 2050		1,131,960		274,974

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At June 30, 2025, the aggregate gross unrealized appreciation (depreciation) and net unrealized appreciation (depreciation) for all securities, as computed on a federal income tax basis for each Fund were as follows:

Fund	Appreciation		Depreciation			Net
Conservative Allocation	$	3,120,235	$	(1,588,637	)	$	1,531,598
Moderate Allocation		13,602,717		(2,406,545	)		11,196,172
Aggressive Allocation		6,778,291		(545,855	)		6,232,436
Diversified Income		5,099,882		(1,863,351	)		3,236,531
Core Bond		459,819		(3,793,922	)		(3,334,103	)
Large Cap Value		40,616,340		(3,047,532	)		37,568,808
Large Cap Growth		78,836,786		(1,589,523	)		77,247,263
Mid Cap		59,876,568		(249,024	)		59,627,544
Madison Target Retirement 2020		471,921		(27,761	)		444,160
Madison Target Retirement 2030		3,783,795		(160,610	)		3,623,185
Madison Target Retirement 2040		4,230,703		(152,479	)		4,078,224
Madison Target Retirement 2050		4,312,343		(149,984	)		4,162,359

10. CAPITAL SHARES AND AFFILIATED OWNERSHIP

All capital shares outstanding at June 30, 2025, are owned by separate investment accounts and/or pension plans of TruStage.

The Allocation Funds invest in Underlying Funds, including the Madison Funds (the “Affiliated Underlying Funds”), which may be deemed to be under common control because of the same or affiliated investment adviser and membership in a common family of investment companies. Madison Funds’ historical financial information is available to you at no cost on the SEC’s website at www.sec.gov, by calling 1-800-877-6089 or by visiting the Madison Funds’ website at www.madisonfunds.com. (the “Affiliated Issuers”). A summary of the transactions with each Affiliated Underlying Fund during the period ended June 30, 2025 follows:

Fund/Underlying Fund	Beginning value as of 12/31/2024		Gross Additions		Gross Sales			Realized Gain (Loss)			Change in Unrealized Appreciation (depreciation)			Value at 6/30/2025		Shares		Dividend Income		Distributions Received1
Conservative Allocation Fund
Madison Core Bond Fund Class R6	$	19,488,271	$	–	$	–		$	–		$	419,815		$	19,908,086		2,209,555	$	378,626	$	–
Madison Large Cap Fund Class R6		–		–		(1,224,827	)		(11,240	)		73,855			3,985,781		133,304		–		–
Totals	$	24,636,264	$	–	$	(1,224,827	)	$	(11,240	)	$	493,670			23,893,867			$	378,626	$	–
Moderate Allocation Fund
Madison Core Bond Fund Class R6		27,172,934		–		–			–			585,358			27,758,292		3,080,832		527,927		–
Madison Large Cap Fund Class R6		–		–		(4,556,043	)		640,992			(394,895	)		14,095,634		471,426		–		–
Madison Mid Cap Fund Class R6		1,095,108		–		–			–			10,387			1,105,495		64,915		–		–
Totals	$	46,673,623	$	–	$	(4,556,043	)	$	640,992		$	200,850			42,959,421			$	527,927	$	–

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Fund/Underlying Fund	Beginning value as of 12/31/24		Gross Additions		Gross Sales			Realized Gain (Loss)			Change in Unrealized Appreciation (depreciation)			Value at 6/30/2025		Shares		Dividend Income		Distributions Received1
Aggressive Allocation Fund
Madison Core Bond Fund Class R6	$	5,374,007	$	644,996	$	(374,208	)	$	(78,022	)	$	198,487		$	5,765,260		639,873	$	109,149	$	–
Madison Large Cap Fund Class R6		–		125,000		(1,383,690	)		93,157			65,022			6,848,307		229,040		–		–
Madison Mid Cap Fund Class R6		825,556		–		(246,284	)		87,796			(121,351	)		545,717		32,044		–		–
Totals	$	14,148,380	$	769,996	$	(2,004,182	)	$	102,931		$	142,158			13,159,284			$	109,149	$	–
Diversified Income Fund
Madison Aggregate Bond ETF		27,081,000		298,913		(2,026,955	)		5,204			405,587			25,763,749		1,265,000		594,791		–
Madison Covered Call ETF		29,846,208		1,300,050		(6,646,640	)		(874,535	)		348,667			22,673,700		1,220,000		789,000		–
Madison Dividend Value ETF		26,028,800		–		(1,096,875	)		107,500			1,057,024			27,396,499		1,235,000		237,229		–
Madison Short-Term Strategic Income ETF		31,796,875		–		–			–			428,281			32,225,156		1,562,500		732,875		–
Totals	$	114,752,883	$	1,598,963	$	(9,770,470	)	$	(761,831	)	$	2,239,559			108,059,104			$	2,353,895	$	–

¹Distributions received include distributions from net investment income and from capital gains from the underlying funds.

11. CONCENTRATION OF RISKS

Investing in certain financial instruments involves certain risks. Risks associated with these instruments include potential for an illiquid secondary market for the instruments or inability of counterparties to perform under the terms of the contracts, changes in the value of foreign currency relative to the U.S. dollar and volatility resulting from an imperfect correlation between the movements in the prices of the instruments and the prices of the underlying securities and interest rates being hedged.

Investing in foreign securities involves certain risks not necessarily found in U.S. markets. These include risks associated with adverse changes in economic, political, regulatory and other conditions, changes in currency exchange rates, exchange control regulations, expropriation of assets or nationalization, imposition of withholding taxes on dividend or interest payments or capital gains, and possible difficulty in obtaining and enforcing judgments against foreign entities. Further, issuers of foreign securities are subject to different, and often less comprehensive, accounting, reporting and disclosure requirements than domestic issuers.

Slowing global economic growth, the risks associated with ongoing trade negotiations with China, the possibility of changes to some international trade agreements, tensions or open conflict between nations, such as between Russia and Ukraine, or political or economic dysfunction within some nations that are major producers of oil could affect the economies of many nations, including the United States, in ways that cannot necessarily be foreseen at the present time.

The Core Bond Fund is subject to derivatives risk, which is the risk that loss may result from investments in options, forwards, futures, swaps and other derivatives instruments. These instruments may be illiquid, difficult to price and leveraged so that small changes in the value of the underlying instruments may produce disproportionate losses to the Fund. Derivatives are also subject to counterparty risk, which is the risk that the other party to the transaction will not fulfill its contractual obligations.

51

Ultra Series Fund | June 30, 2025

Notes to Financial Statements (unaudited) - concluded

The Target Allocation Funds and Target Date Funds are fund of funds, meaning that each invests primarily in Underlying Funds, including ETFs. Thus, each Fund’s investment performance and its ability to achieve its investment goal are directly related to the performance of the Underlying Funds in which it invests; and the Underlying Fund’s performance, in turn, depends on the particular securities in which that Underlying Fund invests and the expenses of that Fund. Accordingly, these Funds are subject to the risks of the Underlying Funds in direct proportion to the allocation of their respective assets among the Underlying Funds. Additionally, the Target Allocation Funds and Target Date Funds are subject to asset allocation risk and manager risk. Manager risk (i.e., fund selection risk) is the risk that the Underlying Fund(s) selected to fulfill a particular asset class underperforms their peers. Asset allocation risk is the risk that the allocation of the Fund’s assets among the various asset classes and market segments will cause the Fund to underperform other Funds with a similar investment objective.

The Funds may be subject to interest rate risk which is the risk that the value of your investment will fluctuate with changes in interest rates. Typically, a rise in interest rates causes a decline in the fair value of income-bearing securities. When interest rates rise, bond prices fall; generally the longer a bond’s maturity, the more sensitive it is to risk. Federal Reserve policy changes may expose fixed-income and related markets to heightened volatility and may reduce liquidity for certain Fund investments, which could cause the value of a fund’s investments and share price to decline. The Core Bond Fund may invest in derivatives tied to fixed-income markets and may be more substantially exposed to these risks than a Fund that does not invest in derivatives.

U.S. and international markets have experienced and may continue to experience significant periods of volatility in recent month and years due to a number of economic, political and global macro factors including uncertainty regarding inflation and interest rate levels, the possibility of a national or global recession, trade tensions, political events, and wars in Europe and in the Middle East. These developments, as well as other events, could result in further market volatility and negatively affect financial asset prices, the liquidity of certain securities and the normal operations of securities exchanges and other markets, despite government efforts to address market disruptions. Continuing market volatility as a result of recent market conditions or other events may have adverse effects on the value of the Funds’ portfolio holdings.

In addition to the other risks described above and in the Prospectus, you should understand what we refer to as “unknown market risks.” While investments in securities have been keystones in wealth building and management, at times these investments have produced surprises. Those who enjoyed growth and income of their investments generally were rewarded for the risks they took by investing in the markets. Although the Investment Adviser seeks to appropriately address and manage the risks identified and disclosed to you in connection with the management of the securities in the Funds, you should understand that the very nature of the securities markets includes the possibility that there may be additional risks of which we are not aware. We certainly seek to identify all applicable risks and then appropriately address them, take appropriate action to reasonably manage them and to make you aware of them so you can determine if they exceed your risk tolerance. Nevertheless, the often volatile nature of the securities markets and the global economy in which we work suggests that the risk of the unknown is something to consider in connection with an investment in securities. Unforeseen events could under certain circumstances produce a material loss of the value of some or all of the securities we manage for you in the Funds.

52 

Ultra Series Fund | June 30, 2025

Notes to Financial Statements (unaudited) - concluded

12. SUBSEQUENT EVENTS

Management has evaluated the impact of all subsequent events on the Funds through the date the financial statements were available for issue. No other events have taken place that meet the definition of a subsequent event that requires adjustment to, or disclosure in the financial statements.

53

Item 8. Changes in and Disagreements with Accountants for Open-End Management Investment Companies.

Not applicable.

Item 9. Proxy Disclosures for Open-End Management Investment Companies.

Not applicable.

Item 10. Remuneration Paid to Directors, Officers, and Others of Open-End Management Investment Companies.

The registrant discloses remuneration paid to directors, officers, and others as part of the financial statements included in item 7 of this Form. 

Item 11. Statement Regarding Basis for Approval of Investment Advisory Contract.

There were no investment advisory contracts for the registrant’s board of directors to approve during the Fund’s most recent fiscal half-year.

Item 12. Disclosure of Proxy Voting Policies and Procedures for Closed-End Management Investment Companies.

Not applicable.

Item 13. Portfolio Managers of Closed-End Management Investment Companies.

Not applicable.

Item 14. Purchases of Equity Securities by Closed-End Management Investment Company and Affiliated Purchasers.

Not applicable.

Item 15. Submission of Matters to a Vote of Security Holders.

The registrant does not normally hold shareholder meetings. There have been no changes to the registrant's procedures during the period covered by this report.

Item 16. Controls and Procedures.

(a) The registrant’s President (principal executive officer) and Treasurer (principal financial officer) determined that the registrant’s disclosure controls and procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940 (the "Act")) are effective, based on their evaluation of these controls and procedures required by Rule 30a-3(b) under the Act and Rules 13a-15(b) or 15d-15(b) under the Securities Exchange Act of 1934 within 90 days of the date of this report. There were no significant changes in the registrant’s internal controls or in other factors that could significantly affect these controls subsequent to the date of their evaluation. The officers identified no significant deficiencies or material weaknesses.

(b) There were no changes in the registrant’s internal control over financial reporting (as defined in Rule 30a-3(d) under the Act) that occurred during the period covered by this report that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting.

Item 17. Disclosure of Securities Lending Activities for Closed-End Management Investment Companies.

Not applicable.

Item 18. Recovery of Erroneously Awarded Compensation.

The registrant did not require an accounting restatement that required recovery of erroneously awarded compensation pursuant to the registrant’s compensation recovery policy required by the listing standards adopted pursuant to 17 CFR 240.10D-1.

Item 19. Exhibits.

(a) (1) Code of ethics – See Item 2.

(2) Not applicable.

(3) Certifications of principal executive and principal financial officers as required by Rule 30a-2(a) under the Act. – Filed herewith.

(4) Not applicable.

(5) There was no change in the registrant’s independent public accountant for the period covered by this report.

(b) Certification of principal executive and principal financial officers as required by Rule 30a-2(b) under the Act. - Filed herewith.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the Registrant has duly caused this Report to be signed on its behalf by the undersigned, thereunto duly authorized.

Madison Funds

/s/ Steve J. Fredricks 

Steve J. Fredricks, Chief Legal Officer & Chief Compliance Officer

Date: August 29, 2025

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this Report has been signed below by the following persons on behalf of the Registrant and in the capacities and on the dates indicated.

/s/ Patrick F. Ryan

Patrick F. Ryan, Principal Executive Officer

Date: August 29, 2025

/s/ Greg D. Hoppe

Greg D. Hoppe, Principal Financial Officer & Principal Accounting Officer

Date: August 29, 2025

EX-99.CERT

Exhibit 99.CERT

Financial Statement Certifications

I, Greg Hoppe, certify that:

1. I have reviewed this report on Form N-CSR of Ultra Series Fund;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the schedules of investments included in this report fairly present in all material respects the investments of the registrant as of the end of the fiscal quarter for which the report is filed;

4. The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940) and internal control over financial reporting (as defined in Rule 30a-3(d) under the Investment Company Act of 1940) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of a date within 90 days prior to the filing date of this report, based on such evaluation; and

(d) Disclosed in this report there were no changes in the registrant’s internal control over financial reporting during the period covered by this report that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer(s) and I have disclosed to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions): 

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize, and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: August 29, 2025

/s/ Greg Hoppe 

Greg Hoppe 
Principal Financial Officer and Principal Accounting Officer

I, Patrick F. Ryan, certify that:

1. I have reviewed this report on Form N-CSR of Ultra Series Fund;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the schedules of investments included in this report fairly present in all material respects the investments of the registrant as of the end of the fiscal quarter for which the report is filed;

4. The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940) and internal control over financial reporting (as defined in Rule 30a-3(d) under the Investment Company Act of 1940) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of a date within 90 days prior to the filing date of this report, based on such evaluation; and

(d) Disclosed in this report there were no changes in the registrant’s internal control over financial reporting during the period covered by this report that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer(s) and I have disclosed to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions): 

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize, and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: August 29, 2025

/s/ Patrick F. Ryan

Patrick F. Ryan
Principal Executive Officer

EX-99.906

Exhibit 99.906 CERT 

Certification under Section 906 of Sarbanes Oxley (18 USC 1350)

Ultra Series Fund
Semi-Annual Report dated June 30, 2025

The undersigned certify that this periodic report containing the financial statements fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934 (15 U.S.C 78m or 78o(d)) and the information contained in this periodic report fairly presents, in all material respects, the financial condition and results of operations of the issuer.

/s/Patrick F. Ryan	/s/ Greg Hoppe
Patrick F. Ryan	Greg Hoppe
Principal Executive Officer	Principal Financial Officer and Principal Accounting Officer

Dated this 29^th day of August, 2025

A signed original of this written statement required by Section 906, or other document authenticating, acknowledging, or otherwise adopting the signature that appears in typed form within the electronic version of this written statement required by Section 906, has been provided to Ultra Series Fund and will be retained by Ultra Series Fund and furnished to the SEC or its staff upon request.

XML

Form N-CSR Cover	6 Months Ended
	Jun. 30, 2025
Shareholder Report [Line Items]
Document Type	N-CSRS
Amendment Flag	false
Registrant Name	Ultra Series Fund
Entity Central Index Key	0000732697
Entity Investment Company Type	N-1A
Document Period End Date	Jun. 30, 2025

XML

Shareholder Report

6 Months Ended

Jun. 30, 2025

USD ($)

Holdings

Shareholder Report [Line Items]

Document Type

N-CSRS

Amendment Flag

false

Registrant Name

Ultra Series Fund

Entity Central Index Key

0000732697

Entity Investment Company Type

N-1A

Document Period End Date

Jun. 30, 2025

Conservative Allocation Fund Class I

Shareholder Report [Line Items]

Fund Name

Conservative Allocation Fund

Class Name

Conservative Allocation Fund Class I

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Conservative Allocation Fund Class I for the period of January 1, 2025 to June 30, 2025.

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$17	0.33%

¹  Annualized.

Expenses Paid, Amount

$ 17

Expense Ratio, Percent

0.33%

^[1]

Net Assets

$ 46,984,089

Holdings Count | Holdings

20

Advisory Fees Paid, Amount

$ 70,831

Investment Company, Portfolio Turnover

19.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$46,984,089
# of Portfolio Holdings	20
Portfolio Turnover Rate	19%
Total Advisory Fees Paid	$70,831

Holdings [Text Block]

Portfolio Allocation (% of Net Assets) 

Investment Companies	50.9%
Exchange Traded Funds	47.9%
Short-Term Investments	2.8%
Other Assets and Liabilities, Net	(1.6%)

Exposure Basis Explanation [Text Block]

The Fund invests primarily in shares of other registered investment companies. The Fund’s total net assets will be allocated among various asset classes and underlying funds with target allocations over time of approximately 35% equity investments and 65% fixed income investments.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

Madison Core Bond Fund, Class R6	42.4%
Schwab Intermediate-Term U.S. Treasury ETF	8.5%
Madison Large Cap Fund, Class R6	8.5%
Janus Henderson Mortgage-Backed Securities ETF	7.8%
Invesco S&P 500 Quality ETF	6.6%
Vanguard Information Technology ETF	3.1%
Vanguard FTSE Europe ETF	2.9%
iShares MSCI Emerging Markets Asia ETF	2.6%
Vanguard Short-Term Corporate Bond ETF	2.1%
Distillate U.S. Fundamental Stability & Value ETF	2.1%

Conservative Allocation Fund Class II

Shareholder Report [Line Items]

Fund Name

Conservative Allocation Fund

Class Name

Conservative Allocation Fund Class II

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Conservative Allocation Fund Class II for the period of January 1, 2025 to June 30, 2025.

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class II	$29	0.58%

¹  Annualized.

Expenses Paid, Amount

$ 29

Expense Ratio, Percent

0.58%

^[2]

Net Assets

$ 46,984,089

Holdings Count | Holdings

20

Advisory Fees Paid, Amount

$ 70,831

Investment Company, Portfolio Turnover

19.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$46,984,089
# of Portfolio Holdings	20
Portfolio Turnover Rate	19%
Total Advisory Fees Paid	$70,831

Holdings [Text Block]

Portfolio Allocation (% of Net Assets) 

Investment Companies	50.9%
Exchange Traded Funds	47.9%
Short-Term Investments	2.8%
Other Assets and Liabilities, Net	(1.6%)

Exposure Basis Explanation [Text Block]

The Fund invests primarily in shares of other registered investment companies. The Fund’s total net assets will be allocated among various asset classes and underlying funds with target allocations over time of approximately 35% equity investments and 65% fixed income investments.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

Madison Core Bond Fund, Class R6	42.4%
Schwab Intermediate-Term U.S. Treasury ETF	8.5%
Madison Large Cap Fund, Class R6	8.5%
Janus Henderson Mortgage-Backed Securities ETF	7.8%
Invesco S&P 500 Quality ETF	6.6%
Vanguard Information Technology ETF	3.1%
Vanguard FTSE Europe ETF	2.9%
iShares MSCI Emerging Markets Asia ETF	2.6%
Vanguard Short-Term Corporate Bond ETF	2.1%
Distillate U.S. Fundamental Stability & Value ETF	2.1%

Moderate Allocation Fund Class I

Shareholder Report [Line Items]

Fund Name

Moderate Allocation Fund

Class Name

Moderate Allocation Fund Class I

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Moderate Allocation Fund Class I for the period of January 1, 2025 to June 30, 2025.

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$17	0.33%

¹  Annualized.

Expenses Paid, Amount

$ 17

Expense Ratio, Percent

0.33%

^[3]

Net Assets

$ 101,959,298

Holdings Count | Holdings

20

Advisory Fees Paid, Amount

$ 153,356

Investment Company, Portfolio Turnover

25.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$101,959,298
# of Portfolio Holdings	20
Portfolio Turnover Rate	25%
Total Advisory Fees Paid	$153,356

Holdings [Text Block]

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	54.7%
Investment Companies	42.1%
Short-Term Investments	6.7%
Other Assets and Liabilities, Net	(3.5%)

Exposure Basis Explanation [Text Block]

The Fund invests primarily in shares of other registered investment companies. The Fund’s total net assets will be allocated among various asset classes and underlying funds with target allocations over time of approximately 60% equity investments and 40% fixed income investments.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

Madison Core Bond Fund, Class R6	27.2%
Madison Large Cap Fund, Class R6	13.8%
Invesco S&P 500 Quality ETF	9.7%
Vanguard FTSE Europe ETF	5.5%
Vanguard Information Technology ETF	5.1%
iShares MSCI Emerging Markets Asia ETF	4.8%
Janus Henderson Mortgage-Backed Securities ETF	4.2%
Distillate U.S. Fundamental Stability & Value ETF	3.6%
iShares Core S&P Small-Cap ETF	3.2%
Schwab Intermediate-Term U.S. Treasury ETF	3.1%

Moderate Allocation Fund Class II

Shareholder Report [Line Items]

Fund Name

Moderate Allocation Fund

Class Name

Moderate Allocation Fund Class II

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Moderate Allocation Fund Class II for the period of January 1, 2025 to June 30, 2025.

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class II	$29	0.58%

¹  Annualized.

Expenses Paid, Amount

$ 29

Expense Ratio, Percent

0.58%

^[4]

Net Assets

$ 101,959,298

Holdings Count | Holdings

20

Advisory Fees Paid, Amount

$ 153,356

Investment Company, Portfolio Turnover

25.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$101,959,298
# of Portfolio Holdings	20
Portfolio Turnover Rate	25%
Total Advisory Fees Paid	$153,356

Holdings [Text Block]

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	54.7%
Investment Companies	42.1%
Short-Term Investments	6.7%
Other Assets and Liabilities, Net	(3.5%)

Exposure Basis Explanation [Text Block]

The Fund invests primarily in shares of other registered investment companies. The Fund’s total net assets will be allocated among various asset classes and underlying funds with target allocations over time of approximately 60% equity investments and 40% fixed income investments.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

Madison Core Bond Fund, Class R6	27.2%
Madison Large Cap Fund, Class R6	13.8%
Invesco S&P 500 Quality ETF	9.7%
Vanguard FTSE Europe ETF	5.5%
Vanguard Information Technology ETF	5.1%
iShares MSCI Emerging Markets Asia ETF	4.8%
Janus Henderson Mortgage-Backed Securities ETF	4.2%
Distillate U.S. Fundamental Stability & Value ETF	3.6%
iShares Core S&P Small-Cap ETF	3.2%
Schwab Intermediate-Term U.S. Treasury ETF	3.1%

Aggressive Allocation Fund Class I

Shareholder Report [Line Items]

Fund Name

Aggressive Allocation Fund

Class Name

Aggressive Allocation Fund Class I

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Aggressive Allocation Fund Class I for the period of January 1, 2025 to June 30, 2025

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$17	0.32%

¹  Annualized.

Expenses Paid, Amount

$ 17

Expense Ratio, Percent

0.32%

^[5]

Net Assets

$ 41,383,479

Holdings Count | Holdings

19

Advisory Fees Paid, Amount

$ 59,918

Investment Company, Portfolio Turnover

27.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$41,383,479
# of Portfolio Holdings	19
Portfolio Turnover Rate	27%
Total Advisory Fees Paid	$59,918

Holdings [Text Block]

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	64.5%
Investment Companies	31.8%
Short-Term Investments	8.7%
Other Assets and Liabilities, Net	(5.0%)

Exposure Basis Explanation [Text Block]

The Fund invests primarily in shares of other registered investment companies. The Fund’s total net assets will be allocated among various asset classes and underlying funds with target allocations over time of approximately 80% equity investments and 20% fixed income investments.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

Madison Large Cap Fund, Class R6	16.5%
Madison Core Bond Fund, Class R6	13.9%
Invesco S&P 500 Quality ETF	12.4%
Vanguard FTSE Europe ETF	8.2%
Vanguard Information Technology ETF	7.3%
Distillate U.S. Fundamental Stability & Value ETF	6.8%
iShares MSCI Emerging Markets Asia ETF	6.3%
SPDR S&P Bank ETF	4.5%
iShares Core S&P Small-Cap ETF	4.1%
Vanguard FTSE All-World ex-U.S. ETF	3.5%

Aggressive Allocation Fund Class II

Shareholder Report [Line Items]

Fund Name

Aggressive Allocation Fund

Class Name

Aggressive Allocation Fund Class II

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Aggressive Allocation Fund Class II for the period of January 1, 2025 to June 30, 2025.

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class II	$29	0.57%

¹  Annualized.

Expenses Paid, Amount

$ 29

Expense Ratio, Percent

0.57%

^[6]

Net Assets

$ 41,383,479

Holdings Count | Holdings

19

Advisory Fees Paid, Amount

$ 59,918

Investment Company, Portfolio Turnover

27.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$41,383,479
# of Portfolio Holdings	19
Portfolio Turnover Rate	27%
Total Advisory Fees Paid	$59,918

Holdings [Text Block]

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	64.5%
Investment Companies	31.8%
Short-Term Investments	8.7%
Other Assets and Liabilities, Net	(5.0%)

Exposure Basis Explanation [Text Block]

The Fund invests primarily in shares of other registered investment companies. The Fund’s total net assets will be allocated among various asset classes and underlying funds with target allocations over time of approximately 80% equity investments and 20% fixed income investments.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

Madison Large Cap Fund, Class R6	16.5%
Madison Core Bond Fund, Class R6	13.9%
Invesco S&P 500 Quality ETF	12.4%
Vanguard FTSE Europe ETF	8.2%
Vanguard Information Technology ETF	7.3%
Distillate U.S. Fundamental Stability & Value ETF	6.8%
iShares MSCI Emerging Markets Asia ETF	6.3%
SPDR S&P Bank ETF	4.5%
iShares Core S&P Small-Cap ETF	4.1%
Vanguard FTSE All-World ex-U.S. ETF	3.5%

Diversified Income Fund Class I

Shareholder Report [Line Items]

Fund Name

Diversified Income Fund

Class Name

Diversified Income Fund Class I

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Diversified Income Fund Class I for the period of January 1, 2025 to June 30, 2025.

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$14	0.27%

¹  Annualized.

Expenses Paid, Amount

$ 14

Expense Ratio, Percent

0.27%

^[7]

Net Assets

$ 144,073,661

Holdings Count | Holdings

16

Advisory Fees Paid, Amount

$ 180,875

Investment Company, Portfolio Turnover

16.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$144,073,661
# of Portfolio Holdings	16
Portfolio Turnover Rate	16%
Total Advisory Fees Paid	$180,875

Holdings [Text Block]

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	99.4%
Short-Term Investments	1.4%
Mortgage Backed Securities	0.0%
Commercial Mortgage-Backed Securities	0.0%
Other Assets and Liabilities, Net	(0.8%)

Exposure Basis Explanation [Text Block]

The Fund primarily invests in shares of other registered investment companies, diversifying across various asset classes according to an asset allocation approximately 60% in equity investments and 40% in fixed income investments.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

Madison Short-Term Strategic Income ETF	22.4%
Madison Dividend Value ETF	19.0%
Madison Aggregate Bond ETF	17.9%
Madison Covered Call ETF	15.7%
SPDR Portfolio High Yield Bond ETF	10.0%
Janus Henderson Mortgage-Backed Securities ETF	4.9%
Global X MLP ETF	4.0%
Schwab U.S. Dividend Equity ETF	3.4%
iShares 5-10 Year Investment Grade Corporate Bond ETF	2.0%
Federal National Mortgage Association, 7.000%, due 11/01/31	0.0%

Diversified Income Fund Class II

Shareholder Report [Line Items]

Fund Name

Diversified Income Fund

Class Name

Diversified Income Fund Class II

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Diversified Income Fund Class II for the period of January 1, 2025 to June 30, 2025.

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class II	$26	0.52%

¹  Annualized.

Expenses Paid, Amount

$ 26

Expense Ratio, Percent

0.52%

^[8]

Net Assets

$ 144,073,661

Holdings Count | Holdings

16

Advisory Fees Paid, Amount

$ 180,875

Investment Company, Portfolio Turnover

16.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$144,073,661
# of Portfolio Holdings	16
Portfolio Turnover Rate	16%
Total Advisory Fees Paid	$180,875

Holdings [Text Block]

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	99.4%
Short-Term Investments	1.4%
Mortgage Backed Securities	0.0%
Commercial Mortgage-Backed Securities	0.0%
Other Assets and Liabilities, Net	(0.8%)

Exposure Basis Explanation [Text Block]

The Fund primarily invests in shares of other registered investment companies, diversifying across various asset classes according to an asset allocation approximately 60% in equity investments and 40% in fixed income investments.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

Madison Short-Term Strategic Income ETF	22.4%
Madison Dividend Value ETF	19.0%
Madison Aggregate Bond ETF	17.9%
Madison Covered Call ETF	15.7%
SPDR Portfolio High Yield Bond ETF	10.0%
Janus Henderson Mortgage-Backed Securities ETF	4.9%
Global X MLP ETF	4.0%
Schwab U.S. Dividend Equity ETF	3.4%
iShares 5-10 Year Investment Grade Corporate Bond ETF	2.0%
Federal National Mortgage Association, 7.000%, due 11/01/31	0.0%

Core Bond Fund Class I

Shareholder Report [Line Items]

Fund Name

Core Bond Fund

Class Name

Core Bond Fund Class I

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Core Bond Fund Class I for the period of January 1, 2025 to June 30, 2025.

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$29	0.58%

¹  Annualized.

Expenses Paid, Amount

$ 29

Expense Ratio, Percent

0.58%

^[9]

Net Assets

$ 53,754,931

Holdings Count | Holdings

254

Advisory Fees Paid, Amount

$ 172,883

Investment Company, Portfolio Turnover

8.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$53,754,931
# of Portfolio Holdings	254
Portfolio Turnover Rate	8%
Total Advisory Fees Paid	$172,883

Holdings [Text Block]

Portfolio Allocation (% of Net Assets) 

Mortgage Backed Securities	41.1%
Corporate Notes and Bonds	25.7%
U.S. Government and Agency Obligations	18.9%
Collateralized Mortgage Obligations	6.5%
Foreign Corporate Bonds	3.1%
Short-Term Investments	2.5%
Asset Backed Securities	1.2%
Commercial Mortgage-Backed Securities	0.8%
Other Assets and Liabilities, Net	0.2%

Exposure Basis Explanation [Text Block]

The Fund invests primary in fixed income securities such as Corporate, U.S. Government and Foreign debt securities. In addition the fund also invested in asset backed, mortgage-backed and commercial mortgage-backed securities.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

Federal Home Loan Mortgage Corp., 2.500%, due 01/01/52	1.5%
U.S. Treasury Bonds, 6.625%, due 02/15/27	1.5%
U.S. Treasury Notes, 4.375%, due 05/15/34	1.4%
U.S. Treasury Bonds, 4.500%, due 05/15/38	1.4%
U.S. Treasury Notes, 4.000%, due 02/15/34	1.4%
U.S. Treasury Notes, 2.875%, due 05/15/28	1.4%
U.S. Treasury Notes, 2.625%, due 02/15/29	1.3%
U.S. Treasury Bonds, 4.250%, due 08/15/54	1.3%
U.S. Treasury Bonds, 3.750%, due 08/15/41	1.3%
Federal National Mortgage Association, 4.500%, due 08/01/52	1.1%

Core Bond Fund Class II

Shareholder Report [Line Items]

Fund Name

Core Bond Fund

Class Name

Core Bond Fund Class II

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Core Bond Fund Class II for the period of January 1, 2025 to June 30, 2025

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class II	$42	0.83%

¹  Annualized.

Expenses Paid, Amount

$ 42

Expense Ratio, Percent

0.83%

^[10]

Net Assets

$ 53,754,931

Holdings Count | Holdings

254

Advisory Fees Paid, Amount

$ 172,883

Investment Company, Portfolio Turnover

8.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$53,754,931
# of Portfolio Holdings	254
Portfolio Turnover Rate	8%
Total Advisory Fees Paid	$172,883

Holdings [Text Block]

Portfolio Allocation (% of Net Assets) 

Mortgage Backed Securities	41.1%
Corporate Notes and Bonds	25.7%
U.S. Government and Agency Obligations	18.9%
Collateralized Mortgage Obligations	6.5%
Foreign Corporate Bonds	3.1%
Short-Term Investments	2.5%
Asset Backed Securities	1.2%
Commercial Mortgage-Backed Securities	0.8%
Other Assets and Liabilities, Net	0.2%

Exposure Basis Explanation [Text Block]

The Fund invests primary in fixed income securities such as Corporate, U.S. Government and Foreign debt securities. In addition the fund also invested in asset backed, mortgage-backed and commercial mortgage-backed securities.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

Federal Home Loan Mortgage Corp., 2.500%, due 01/01/52	1.5%
U.S. Treasury Bonds, 6.625%, due 02/15/27	1.5%
U.S. Treasury Notes, 4.375%, due 05/15/34	1.4%
U.S. Treasury Bonds, 4.500%, due 05/15/38	1.4%
U.S. Treasury Notes, 4.000%, due 02/15/34	1.4%
U.S. Treasury Notes, 2.875%, due 05/15/28	1.4%
U.S. Treasury Notes, 2.625%, due 02/15/29	1.3%
U.S. Treasury Bonds, 4.250%, due 08/15/54	1.3%
U.S. Treasury Bonds, 3.750%, due 08/15/41	1.3%
Federal National Mortgage Association, 4.500%, due 08/01/52	1.1%

Large Cap Value Fund Class I

Shareholder Report [Line Items]

Fund Name

Large Cap Value Fund

Class Name

Large Cap Value Fund Class I

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Large Cap Value Fund Class I for the period of January 1, 2025 to June 30, 2025.

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$32	0.63%

¹  Annualized.

Expenses Paid, Amount

$ 32

Expense Ratio, Percent

0.63%

^[11]

Net Assets

$ 164,797,008

Holdings Count | Holdings

40

Advisory Fees Paid, Amount

$ 521,825

Investment Company, Portfolio Turnover

7.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$164,797,008
# of Portfolio Holdings	40
Portfolio Turnover Rate	7%
Total Advisory Fees Paid	$521,825

Holdings [Text Block]

Sector Allocation (% of Net Assets) 

Industrials	20.3%
Financials	20.0%
Health Care	14.1%
Energy	8.9%
Consumer Discretionary	8.7%
Information Technology	8.1%
Consumer Staples	7.3%
Utilities	3.6%
Equity Real Estate Investment Trusts (REITs)	2.8%
Communication Services	2.7%
Materials	1.9%
Short-Term Investments	1.6%
Other Assets and Liabilities, Net	0.0%

Exposure Basis Explanation [Text Block]

The Fund invests primarily in common stocks of large-cap companies as defined as those in the Russell 1000^® Value Index. The Fund targets to maintain at least 80% of its net assets in such stocks.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

CME Group, Inc.	4.3%
Automatic Data Processing, Inc.	4.0%
Blackrock, Inc.	3.9%
Morgan Stanley	3.8%
Honeywell International, Inc.	3.8%
NextEra Energy, Inc.	3.5%
Home Depot, Inc.	3.5%
Texas Instruments, Inc.	3.5%
Johnson & Johnson	3.3%
Fastenal Co.	3.3%

Large Cap Value Fund Class II

Shareholder Report [Line Items]

Fund Name

Large Cap Value Fund

Class Name

Large Cap Value Fund Class II

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Large Cap Value Fund Class II for the period of January 1, 2025 to June 30, 2025.

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class II	$44	0.88%

¹  Annualized.

Expenses Paid, Amount

$ 44

Expense Ratio, Percent

0.88%

^[12]

Net Assets

$ 164,797,008

Holdings Count | Holdings

40

Advisory Fees Paid, Amount

$ 521,825

Investment Company, Portfolio Turnover

7.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$164,797,008
# of Portfolio Holdings	40
Portfolio Turnover Rate	7%
Total Advisory Fees Paid	$521,825

Holdings [Text Block]

Sector Allocation (% of Net Assets) 

Industrials	20.3%
Financials	20.0%
Health Care	14.1%
Energy	8.9%
Consumer Discretionary	8.7%
Information Technology	8.1%
Consumer Staples	7.3%
Utilities	3.6%
Equity Real Estate Investment Trusts (REITs)	2.8%
Communication Services	2.7%
Materials	1.9%
Short-Term Investments	1.6%
Other Assets and Liabilities, Net	0.0%

Exposure Basis Explanation [Text Block]

The Fund invests primarily in common stocks of large-cap companies as defined as those in the Russell 1000^® Value Index. The Fund targets to maintain at least 80% of its net assets in such stocks.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

CME Group, Inc.	4.3%
Automatic Data Processing, Inc.	4.0%
Blackrock, Inc.	3.9%
Morgan Stanley	3.8%
Honeywell International, Inc.	3.8%
NextEra Energy, Inc.	3.5%
Home Depot, Inc.	3.5%
Texas Instruments, Inc.	3.5%
Johnson & Johnson	3.3%
Fastenal Co.	3.3%

Large Cap Growth Fund Class I

Shareholder Report [Line Items]

Fund Name

Large Cap Growth Fund

Class Name

Large Cap Growth Fund Class I

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Large Cap Growth Fund Class I for the period of January 1, 2025 to June 30, 2025.

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$41	0.83%

¹  Annualized.

Expenses Paid, Amount

$ 41

Expense Ratio, Percent

0.83%

^[13]

Net Assets

$ 180,760,334

Holdings Count | Holdings

31

Advisory Fees Paid, Amount

$ 769,153

Investment Company, Portfolio Turnover

15.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$180,760,334
# of Portfolio Holdings	31
Portfolio Turnover Rate	15%
Total Advisory Fees Paid	$769,153

Holdings [Text Block]

Sector Allocation (% of Net Assets) 

Financials	26.1%
Information Technology	20.0%
Industrials	17.6%
Consumer Discretionary	15.5%
Health Care	11.7%
Communication Services	7.1%
Short-Term Investments	2.0%
Other Assets and Liabilities, Net	0.0%

Exposure Basis Explanation [Text Block]

The Fund invests primarily in common stocks of large-cap companies as defined as those in the Russell 1000^® Growth Index. The Fund targets to maintain at least 80% of its net assets in such stocks.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

Arch Capital Group Ltd.	6.0%
Amazon.com, Inc.	5.3%
Alphabet, Inc., Class C	5.2%
Texas Instruments, Inc.	5.0%
Ferguson Enterprises, Inc.	4.6%
Fiserv, Inc.	4.2%
Visa, Inc., Class A	3.9%
Progressive Corp.	3.8%
PACCAR, Inc.	3.8%
Parker-Hannifin Corp.	3.7%

Large Cap Growth Fund Class II

Shareholder Report [Line Items]

Fund Name

Large Cap Growth Fund

Class Name

Large Cap Growth Fund Class II

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Large Cap Growth Fund Class II for the period of January 1, 2025 to June 30, 2025.

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class II	$54	1.08%

¹  Annualized.

Expenses Paid, Amount

$ 54

Expense Ratio, Percent

1.08%

^[14]

Net Assets

$ 180,760,334

Holdings Count | Holdings

31

Advisory Fees Paid, Amount

$ 769,153

Investment Company, Portfolio Turnover

15.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$180,760,334
# of Portfolio Holdings	31
Portfolio Turnover Rate	15%
Total Advisory Fees Paid	$769,153

Holdings [Text Block]

Sector Allocation (% of Net Assets) 

Financials	26.1%
Information Technology	20.0%
Industrials	17.6%
Consumer Discretionary	15.5%
Health Care	11.7%
Communication Services	7.1%
Short-Term Investments	2.0%
Other Assets and Liabilities, Net	0.0%

Exposure Basis Explanation [Text Block]

The Fund invests primarily in common stocks of large-cap companies as defined as those in the Russell 1000^® Growth Index. The Fund targets to maintain at least 80% of its net assets in such stocks.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

Arch Capital Group Ltd.	6.0%
Amazon.com, Inc.	5.3%
Alphabet, Inc., Class C	5.2%
Texas Instruments, Inc.	5.0%
Ferguson Enterprises, Inc.	4.6%
Fiserv, Inc.	4.2%
Visa, Inc., Class A	3.9%
Progressive Corp.	3.8%
PACCAR, Inc.	3.8%
Parker-Hannifin Corp.	3.7%

Mid Cap Fund Class I

Shareholder Report [Line Items]

Fund Name

Mid Cap Fund

Class Name

Mid Cap Fund Class I

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Mid Cap Fund Class I for the period of January 1, 2025 to June 30, 2025.

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$46	0.93%

¹  Annualized.

Expenses Paid, Amount

$ 46

Expense Ratio, Percent

0.93%

^[15]

Net Assets

$ 122,138,845

Holdings Count | Holdings

32

Advisory Fees Paid, Amount

$ 598,960

Investment Company, Portfolio Turnover

11.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$122,138,845
# of Portfolio Holdings	32
Portfolio Turnover Rate	11%
Total Advisory Fees Paid	$598,960

Holdings [Text Block]

Sector Allocation (% of Net Assets) 

Information Technology	26.0%
Financials	24.1%
Industrials	16.6%
Consumer Discretionary	14.3%
Health Care	8.0%
Communication Services	6.5%
Short-Term Investments	4.6%
Other Assets and Liabilities, Net	(0.1%)

Exposure Basis Explanation [Text Block]

The Fund invests in common stocks, securities convertible into common stocks and related equity securities of midsize companies defined as those companies with market capitalizations of between $500 million and $70 billion.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

Arch Capital Group Ltd.	7.2%
Amphenol Corp., Class A	5.6%
Brown & Brown, Inc.	5.5%
Gartner, Inc.	5.2%
Ross Stores, Inc.	4.7%
Carlisle Cos., Inc.	4.3%
CDW Corp.	4.2%
Copart, Inc.	3.7%
PACCAR, Inc.	3.6%
Liberty Media Corp.-Liberty Formula One, Class C	3.4%

Mid Cap Fund Class II

Shareholder Report [Line Items]

Fund Name

Mid Cap Fund

Class Name

Mid Cap Fund Class II

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Mid Cap Fund Class II for the period of January 1, 2025 to June 30, 2025.

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class II	$59	1.18%

¹  Annualized.

Expenses Paid, Amount

$ 59

Expense Ratio, Percent

1.18%

^[16]

Net Assets

$ 122,138,845

Holdings Count | Holdings

32

Advisory Fees Paid, Amount

$ 598,960

Investment Company, Portfolio Turnover

11.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$122,138,845
# of Portfolio Holdings	32
Portfolio Turnover Rate	11%
Total Advisory Fees Paid	$598,960

Holdings [Text Block]

Sector Allocation (% of Net Assets) 

Information Technology	26.0%
Financials	24.1%
Industrials	16.6%
Consumer Discretionary	14.3%
Health Care	8.0%
Communication Services	6.5%
Short-Term Investments	4.6%
Other Assets and Liabilities, Net	(0.1%)

Exposure Basis Explanation [Text Block]

The Fund invests in common stocks, securities convertible into common stocks and related equity securities of midsize companies defined as those companies with market capitalizations of between $500 million and $70 billion.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

Arch Capital Group Ltd.	7.2%
Amphenol Corp., Class A	5.6%
Brown & Brown, Inc.	5.5%
Gartner, Inc.	5.2%
Ross Stores, Inc.	4.7%
Carlisle Cos., Inc.	4.3%
CDW Corp.	4.2%
Copart, Inc.	3.7%
PACCAR, Inc.	3.6%
Liberty Media Corp.-Liberty Formula One, Class C	3.4%

Madison Target Retirement 2020 Fund Class I

Shareholder Report [Line Items]

Fund Name

Madison Target Retirement 2020 Fund

Class Name

Madison Target Retirement 2020 Fund Class I

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Madison Target Retirement 2020 Fund Class I for the period of January 1, 2025 to June 30, 2025.

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$16	0.31%

¹  Annualized.

Expenses Paid, Amount

$ 16

Expense Ratio, Percent

0.31%

^[17]

Net Assets

$ 10,973,144

Holdings Count | Holdings

17

Advisory Fees Paid, Amount

$ 14,342

Investment Company, Portfolio Turnover

9.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$10,973,144
# of Portfolio Holdings	17
Portfolio Turnover Rate	9%
Total Advisory Fees Paid	$14,342

Holdings [Text Block]

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	98.1%
Short-Term Investments	1.9%
Other Assets and Liabilities, Net	0.0%

Exposure Basis Explanation [Text Block]

The Fund primarily invests in shares of other registered investment companies, following an asset allocation strategy for those planning to retire around 2020. As time progresses, the Fund’s allocation will shift to a more conservative mix, aiming for about 10-30% in stock funds and 70-90% in bond funds.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

Janus Henderson Mortgage-Backed Securities ETF	24.1%
iShares 7-10 Year Treasury Bond ETF	16.8%
Schwab Intermediate-Term U.S. Treasury ETF	16.5%
SPDR Portfolio Short Term Treasury ETF	10.5%
iShares Aaa - A Rated Corporate Bond ETF	7.8%
Invesco S&P 500 Quality ETF	6.2%
iShares MSCI International Quality Factor ETF	3.9%
Distillate U.S. Fundamental Stability & Value ETF	3.3%
Vanguard Information Technology ETF	2.1%
SPDR Portfolio Long Term Treasury ETF	1.6%

Madison Target Retirement 2030 Fund Class I

Shareholder Report [Line Items]

Fund Name

Madison Target Retirement 2030 Fund

Class Name

Madison Target Retirement 2030 Fund Class I

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Madison Target Retirement 2030 Fund Class I for the period of January 1, 2025 to June 30, 2025.

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$16	0.31%

¹  Annualized.

Expenses Paid, Amount

$ 16

Expense Ratio, Percent

0.31%

^[18]

Net Assets

$ 50,933,863

Holdings Count | Holdings

19

Advisory Fees Paid, Amount

$ 61,385

Investment Company, Portfolio Turnover

13.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$50,933,863
# of Portfolio Holdings	19
Portfolio Turnover Rate	13%
Total Advisory Fees Paid	$61,385

Holdings [Text Block]

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	97.0%
Short-Term Investments	3.0%
Other Assets and Liabilities, Net	0.0%

Exposure Basis Explanation [Text Block]

The Fund primarily invests in shares of other registered investment companies, following an asset allocation strategy for those planning to retire around 2030. As time progresses, the Fund’s allocation will shift to a more conservative mix, aiming for about 10-30% in stock funds and 70-90% in bond funds.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

Janus Henderson Mortgage-Backed Securities ETF	18.6%
iShares 7-10 Year Treasury Bond ETF	13.2%
Schwab Intermediate-Term U.S. Treasury ETF	11.7%
Invesco S&P 500 Quality ETF	10.3%
Distillate U.S. Fundamental Stability & Value ETF	8.0%
SPDR Portfolio Short Term Treasury ETF	7.9%
iShares Aaa - A Rated Corporate Bond ETF	6.1%
iShares MSCI International Quality Factor ETF	4.6%
Vanguard Information Technology ETF	3.8%
iShares MSCI Emerging Markets Asia ETF	2.4%

Madison Target Retirement 2040 Fund Class I

Shareholder Report [Line Items]

Fund Name

Madison Target Retirement 2040 Fund

Class Name

Madison Target Retirement 2040 Fund Class I

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Madison Target Retirement 2040 Fund Class I for the period of January 1, 2025 to June 30, 2025.

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$16	0.31%

¹  Annualized.

Expenses Paid, Amount

$ 16

Expense Ratio, Percent

0.31%

^[19]

Net Assets

$ 42,381,174

Holdings Count | Holdings

19

Advisory Fees Paid, Amount

$ 49,619

Investment Company, Portfolio Turnover

18.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$42,381,174
# of Portfolio Holdings	19
Portfolio Turnover Rate	18%
Total Advisory Fees Paid	$49,619

Holdings [Text Block]

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	96.5%
Short-Term Investments	3.4%
Other Assets and Liabilities, Net	0.1%

Exposure Basis Explanation [Text Block]

The Fund primarily invests in shares of other registered investment companies, following an asset allocation strategy for those planning to retire around 2040. As time progresses, the Fund’s allocation will shift to a more conservative mix, aiming for about 10-30% in stock funds and 70-90% in bond funds.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

Invesco S&P 500 Quality ETF	15.4%
Distillate U.S. Fundamental Stability & Value ETF	12.9%
Janus Henderson Mortgage-Backed Securities ETF	11.0%
Schwab Intermediate-Term U.S. Treasury ETF	9.2%
iShares 7-10 Year Treasury Bond ETF	7.9%
iShares MSCI International Quality Factor ETF	7.0%
Vanguard Information Technology ETF	6.5%
iShares Aaa - A Rated Corporate Bond ETF	4.5%
iShares MSCI Emerging Markets Asia ETF	4.1%
SPDR S&P Bank ETF	3.7%

Madison Target Retirement 2050 Fund Class I

Shareholder Report [Line Items]

Fund Name

Madison Target Retirement 2050 Fund

Class Name

Madison Target Retirement 2050 Fund Class I

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Madison Target Retirement 2050 Fund Class I for the period of January 1, 2025 to June 30, 2025.

Shareholder Report Annual or Semi-Annual

Semi-Annual Shareholder Report

Additional Information [Text Block]

You can find additional information about the Fund at www.madisonfunds.com/funds/ultra-series-fund/. You can also request this information by contacting us at 1-800-877-6089.

Additional Information Phone Number

1-800-877-6089

Additional Information Website

www.madisonfunds.com/funds/ultra-series-fund/

Expenses [Text Block]

What were the Fund costs for last period? 

(based on a hypothetical $10,000 investment)

	Cost of a $10,000 investment	Costs paid as a percentage of a $10,000 investment1
Class I	$16	0.31%

¹  Annualized.

Expenses Paid, Amount

$ 16

Expense Ratio, Percent

0.31%

^[20]

Net Assets

$ 36,499,161

Holdings Count | Holdings

19

Advisory Fees Paid, Amount

$ 42,692

Investment Company, Portfolio Turnover

19.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics (As of June 30, 2025) 

Total Net Assets	$36,499,161
# of Portfolio Holdings	19
Portfolio Turnover Rate	19%
Total Advisory Fees Paid	$42,692

Holdings [Text Block]

Portfolio Allocation (% of Net Assets) 

Exchange Traded Funds	96.3%
Short-Term Investments	3.6%
Other Assets and Liabilities, Net	0.1%

Exposure Basis Explanation [Text Block]

The Fund primarily invests in shares of other registered investment companies, following an asset allocation strategy for those planning to retire around 2050. As time progresses, the Fund’s allocation will shift to a more conservative mix, aiming for about 10-30% in stock funds and 70-90% in bond funds.

Largest Holdings [Text Block]

Top Ten Holdings (% of Net Assets) 

Invesco S&P 500 Quality ETF	17.9%
Distillate U.S. Fundamental Stability & Value ETF	15.2%
Janus Henderson Mortgage-Backed Securities ETF	8.0%
iShares MSCI International Quality Factor ETF	7.7%
Vanguard Information Technology ETF	7.2%
Schwab Intermediate-Term U.S. Treasury ETF	6.8%
iShares 7-10 Year Treasury Bond ETF	6.1%
iShares MSCI Emerging Markets Asia ETF	4.9%
iShares MSCI Eurozone ETF	4.2%
SPDR S&P Bank ETF	4.1%

[1] Annualized.

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XML

Shareholder Report, Holdings (Details)	Jun. 30, 2025
Conservative Allocation Fund Class I | Madison Core Bond Fund Class R6 [Member]
Holdings [Line Items]
Percent of Net Asset Value	42.40%
Conservative Allocation Fund Class I | Schwab Intermediate Term US Treasury ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.50%
Conservative Allocation Fund Class I | Madison Large Cap Fund, Class R6 [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.50%
Conservative Allocation Fund Class I | Janus Henderson Mortgage-Backed Securities ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.80%
Conservative Allocation Fund Class I | Invesco S&P 500 Quality ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.60%
Conservative Allocation Fund Class I | Vanguard Information Technology ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.10%
Conservative Allocation Fund Class I | Vanguard FTSE Europe ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.90%
Conservative Allocation Fund Class I | iShares MSCI Emerging Markets Asia ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.60%
Conservative Allocation Fund Class I | Vanguard Short-Term Corporate Bond ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.10%
Conservative Allocation Fund Class I | Distillate U.S. Fundamental Stability & Value ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.10%
Conservative Allocation Fund Class I | Investment Companies [Member]
Holdings [Line Items]
Percent of Net Asset Value	50.90%
Conservative Allocation Fund Class I | Exchange Traded Funds [Member]
Holdings [Line Items]
Percent of Net Asset Value	47.90%
Conservative Allocation Fund Class I | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.80%
Conservative Allocation Fund Class I | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	(1.60%)
Conservative Allocation Fund Class II | Madison Core Bond Fund Class R6 [Member]
Holdings [Line Items]
Percent of Net Asset Value	42.40%
Conservative Allocation Fund Class II | Schwab Intermediate Term US Treasury ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.50%
Conservative Allocation Fund Class II | Madison Large Cap Fund, Class R6 [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.50%
Conservative Allocation Fund Class II | Janus Henderson Mortgage-Backed Securities ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.80%
Conservative Allocation Fund Class II | Invesco S&P 500 Quality ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.60%
Conservative Allocation Fund Class II | Vanguard Information Technology ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.10%
Conservative Allocation Fund Class II | Vanguard FTSE Europe ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.90%
Conservative Allocation Fund Class II | iShares MSCI Emerging Markets Asia ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.60%
Conservative Allocation Fund Class II | Vanguard Short-Term Corporate Bond ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.10%
Conservative Allocation Fund Class II | Distillate U.S. Fundamental Stability & Value ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.10%
Conservative Allocation Fund Class II | Investment Companies [Member]
Holdings [Line Items]
Percent of Net Asset Value	50.90%
Conservative Allocation Fund Class II | Exchange Traded Funds [Member]
Holdings [Line Items]
Percent of Net Asset Value	47.90%
Conservative Allocation Fund Class II | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.80%
Conservative Allocation Fund Class II | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	(1.60%)
Moderate Allocation Fund Class I | Madison Core Bond Fund Class R6 [Member]
Holdings [Line Items]
Percent of Net Asset Value	27.20%
Moderate Allocation Fund Class I | Schwab Intermediate Term US Treasury ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.10%
Moderate Allocation Fund Class I | Madison Large Cap Fund, Class R6 [Member]
Holdings [Line Items]
Percent of Net Asset Value	13.80%
Moderate Allocation Fund Class I | Janus Henderson Mortgage-Backed Securities ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.20%
Moderate Allocation Fund Class I | Invesco S&P 500 Quality ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	9.70%
Moderate Allocation Fund Class I | Vanguard Information Technology ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.10%
Moderate Allocation Fund Class I | Vanguard FTSE Europe ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.50%
Moderate Allocation Fund Class I | iShares MSCI Emerging Markets Asia ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.80%
Moderate Allocation Fund Class I | Distillate U.S. Fundamental Stability & Value ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.60%
Moderate Allocation Fund Class I | iShares Core S&P Small-Cap ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.20%
Moderate Allocation Fund Class I | Investment Companies [Member]
Holdings [Line Items]
Percent of Net Asset Value	42.10%
Moderate Allocation Fund Class I | Exchange Traded Funds [Member]
Holdings [Line Items]
Percent of Net Asset Value	54.70%
Moderate Allocation Fund Class I | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.70%
Moderate Allocation Fund Class I | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	(3.50%)
Moderate Allocation Fund Class II | Madison Core Bond Fund Class R6 [Member]
Holdings [Line Items]
Percent of Net Asset Value	27.20%
Moderate Allocation Fund Class II | Schwab Intermediate Term US Treasury ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.10%
Moderate Allocation Fund Class II | Madison Large Cap Fund, Class R6 [Member]
Holdings [Line Items]
Percent of Net Asset Value	13.80%
Moderate Allocation Fund Class II | Janus Henderson Mortgage-Backed Securities ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.20%
Moderate Allocation Fund Class II | Invesco S&P 500 Quality ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	9.70%
Moderate Allocation Fund Class II | Vanguard Information Technology ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.10%
Moderate Allocation Fund Class II | Vanguard FTSE Europe ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.50%
Moderate Allocation Fund Class II | iShares MSCI Emerging Markets Asia ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.80%
Moderate Allocation Fund Class II | Distillate U.S. Fundamental Stability & Value ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.60%
Moderate Allocation Fund Class II | iShares Core S&P Small-Cap ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.20%
Moderate Allocation Fund Class II | Investment Companies [Member]
Holdings [Line Items]
Percent of Net Asset Value	42.10%
Moderate Allocation Fund Class II | Exchange Traded Funds [Member]
Holdings [Line Items]
Percent of Net Asset Value	54.70%
Moderate Allocation Fund Class II | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.70%
Moderate Allocation Fund Class II | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	(3.50%)
Aggressive Allocation Fund Class I | Invesco S&P 500 Quality ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	12.40%
Aggressive Allocation Fund Class I | Vanguard Information Technology ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.30%
Aggressive Allocation Fund Class I | Vanguard FTSE Europe ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.20%
Aggressive Allocation Fund Class I | iShares MSCI Emerging Markets Asia ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.30%
Aggressive Allocation Fund Class I | Distillate U.S. Fundamental Stability & Value ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.80%
Aggressive Allocation Fund Class I | iShares Core S&P Small-Cap ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.10%
Aggressive Allocation Fund Class I | Madison Large Cap Fund, Class R6 [Member]
Holdings [Line Items]
Percent of Net Asset Value	16.50%
Aggressive Allocation Fund Class I | Madison Core Bond Fund, Class R6 [Member]
Holdings [Line Items]
Percent of Net Asset Value	13.90%
Aggressive Allocation Fund Class I | SPDR S&P Bank ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.50%
Aggressive Allocation Fund Class I | Vanguard FTSE All-World ex-U.S. ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.50%
Aggressive Allocation Fund Class I | Investment Companies [Member]
Holdings [Line Items]
Percent of Net Asset Value	31.80%
Aggressive Allocation Fund Class I | Exchange Traded Funds [Member]
Holdings [Line Items]
Percent of Net Asset Value	64.50%
Aggressive Allocation Fund Class I | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.70%
Aggressive Allocation Fund Class I | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	(5.00%)
Aggressive Allocation Fund Class II | Invesco S&P 500 Quality ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	12.40%
Aggressive Allocation Fund Class II | Vanguard Information Technology ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.30%
Aggressive Allocation Fund Class II | Vanguard FTSE Europe ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.20%
Aggressive Allocation Fund Class II | iShares MSCI Emerging Markets Asia ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.30%
Aggressive Allocation Fund Class II | Distillate U.S. Fundamental Stability & Value ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.80%
Aggressive Allocation Fund Class II | iShares Core S&P Small-Cap ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.10%
Aggressive Allocation Fund Class II | Madison Large Cap Fund, Class R6 [Member]
Holdings [Line Items]
Percent of Net Asset Value	16.50%
Aggressive Allocation Fund Class II | Madison Core Bond Fund, Class R6 [Member]
Holdings [Line Items]
Percent of Net Asset Value	13.90%
Aggressive Allocation Fund Class II | SPDR S&P Bank ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.50%
Aggressive Allocation Fund Class II | Vanguard FTSE All-World ex-U.S. ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.50%
Aggressive Allocation Fund Class II | Investment Companies [Member]
Holdings [Line Items]
Percent of Net Asset Value	31.80%
Aggressive Allocation Fund Class II | Exchange Traded Funds [Member]
Holdings [Line Items]
Percent of Net Asset Value	64.50%
Aggressive Allocation Fund Class II | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.70%
Aggressive Allocation Fund Class II | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	(5.00%)
Diversified Income Fund Class I | Janus Henderson Mortgage-Backed Securities ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.90%
Diversified Income Fund Class I | Madison Short-Term Strategic Income ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	22.40%
Diversified Income Fund Class I | Madison Dividend Value ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	19.00%
Diversified Income Fund Class I | Madison Aggregate Bond ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	17.90%
Diversified Income Fund Class I | Madison Covered Call ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	15.70%
Diversified Income Fund Class I | SPDR Portfolio High Yield Bond ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	10.00%
Diversified Income Fund Class I | Global X MLP ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.00%
Diversified Income Fund Class I | Schwab U.S. Dividend Equity ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.40%
Diversified Income Fund Class I | iShares 5-10 Year Investment Grade Corporate Bond ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.00%
Diversified Income Fund Class I | Federal National Mortgage Association, 7.000%, due 11/01/31 [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.00%
Diversified Income Fund Class I | Exchange Traded Funds [Member]
Holdings [Line Items]
Percent of Net Asset Value	99.40%
Diversified Income Fund Class I | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.40%
Diversified Income Fund Class I | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	(0.80%)
Diversified Income Fund Class I | Mortgage Backed Securities [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.00%
Diversified Income Fund Class I | Commercial Mortgage-Backed Securities [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.00%
Diversified Income Fund Class II | Janus Henderson Mortgage-Backed Securities ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.90%
Diversified Income Fund Class II | Madison Short-Term Strategic Income ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	22.40%
Diversified Income Fund Class II | Madison Dividend Value ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	19.00%
Diversified Income Fund Class II | Madison Aggregate Bond ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	17.90%
Diversified Income Fund Class II | Madison Covered Call ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	15.70%
Diversified Income Fund Class II | SPDR Portfolio High Yield Bond ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	10.00%
Diversified Income Fund Class II | Global X MLP ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.00%
Diversified Income Fund Class II | Schwab U.S. Dividend Equity ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.40%
Diversified Income Fund Class II | iShares 5-10 Year Investment Grade Corporate Bond ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.00%
Diversified Income Fund Class II | Federal National Mortgage Association, 7.000%, due 11/01/31 [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.00%
Diversified Income Fund Class II | Exchange Traded Funds [Member]
Holdings [Line Items]
Percent of Net Asset Value	99.40%
Diversified Income Fund Class II | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.40%
Diversified Income Fund Class II | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	(0.80%)
Diversified Income Fund Class II | Mortgage Backed Securities [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.00%
Diversified Income Fund Class II | Commercial Mortgage-Backed Securities [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.00%
Core Bond Fund Class I | Federal Home Loan Mortgage Corp., 2.500%, due 01/01/52 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.50%
Core Bond Fund Class I | U.S. Treasury Bonds, 6.625%, due 02/15/27 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.50%
Core Bond Fund Class I | U.S. Treasury Notes, 4.375%, due 05/15/34 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.40%
Core Bond Fund Class I | U.S. Treasury Bonds, 4.500%, due 05/15/38 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.40%
Core Bond Fund Class I | U.S. Treasury Notes, 4.000%, due 02/15/34 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.40%
Core Bond Fund Class I | U.S. Treasury Notes, 2.875%, due 05/15/28 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.40%
Core Bond Fund Class I | U.S. Treasury Notes, 2.625%, due 02/15/29 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.30%
Core Bond Fund Class I | U.S. Treasury Bonds, 4.250%, due 08/15/54 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.30%
Core Bond Fund Class I | U.S. Treasury Bonds, 3.750%, due 08/15/41 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.30%
Core Bond Fund Class I | Federal National Mortgage Association, 4.500%, due 08/01/52 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.10%
Core Bond Fund Class I | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.50%
Core Bond Fund Class I | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.20%
Core Bond Fund Class I | Mortgage Backed Securities [Member] [Default Label]
Holdings [Line Items]
Percent of Net Asset Value	41.10%
Core Bond Fund Class I | Corporate Notes and Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	25.70%
Core Bond Fund Class I | U.S. Government and Agency Obligations [Member]
Holdings [Line Items]
Percent of Net Asset Value	18.90%
Core Bond Fund Class I | Collateralized Mortgage Obligations [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.50%
Core Bond Fund Class I | Foreign Corporate Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.10%
Core Bond Fund Class I | Asset Backed Securities [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.20%
Core Bond Fund Class I | Commercial Mortgage-Backed Securities [Member] [Default Label]
Holdings [Line Items]
Percent of Net Asset Value	0.80%
Core Bond Fund Class II | Federal Home Loan Mortgage Corp., 2.500%, due 01/01/52 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.50%
Core Bond Fund Class II | U.S. Treasury Bonds, 6.625%, due 02/15/27 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.50%
Core Bond Fund Class II | U.S. Treasury Notes, 4.375%, due 05/15/34 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.40%
Core Bond Fund Class II | U.S. Treasury Bonds, 4.500%, due 05/15/38 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.40%
Core Bond Fund Class II | U.S. Treasury Notes, 4.000%, due 02/15/34 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.40%
Core Bond Fund Class II | U.S. Treasury Notes, 2.875%, due 05/15/28 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.40%
Core Bond Fund Class II | U.S. Treasury Notes, 2.625%, due 02/15/29 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.30%
Core Bond Fund Class II | U.S. Treasury Bonds, 4.250%, due 08/15/54 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.30%
Core Bond Fund Class II | U.S. Treasury Bonds, 3.750%, due 08/15/41 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.30%
Core Bond Fund Class II | Federal National Mortgage Association, 4.500%, due 08/01/52 [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.10%
Core Bond Fund Class II | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.50%
Core Bond Fund Class II | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.20%
Core Bond Fund Class II | Mortgage Backed Securities [Member] [Default Label]
Holdings [Line Items]
Percent of Net Asset Value	41.10%
Core Bond Fund Class II | Corporate Notes and Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	25.70%
Core Bond Fund Class II | U.S. Government and Agency Obligations [Member]
Holdings [Line Items]
Percent of Net Asset Value	18.90%
Core Bond Fund Class II | Collateralized Mortgage Obligations [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.50%
Core Bond Fund Class II | Foreign Corporate Bonds [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.10%
Core Bond Fund Class II | Asset Backed Securities [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.20%
Core Bond Fund Class II | Commercial Mortgage-Backed Securities [Member] [Default Label]
Holdings [Line Items]
Percent of Net Asset Value	0.80%
Large Cap Value Fund Class I | CME Group, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.30%
Large Cap Value Fund Class I | Automatic Data Processing, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.00%
Large Cap Value Fund Class I | Blackrock, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.90%
Large Cap Value Fund Class I | Morgan Stanley [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.80%
Large Cap Value Fund Class I | Honeywell International, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.80%
Large Cap Value Fund Class I | NextEra Energy, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.50%
Large Cap Value Fund Class I | Home Depot, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.50%
Large Cap Value Fund Class I | Texas Instruments, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.50%
Large Cap Value Fund Class I | Johnson & Johnson [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.30%
Large Cap Value Fund Class I | Fastenal Co. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.30%
Large Cap Value Fund Class I | Industrial Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	20.30%
Large Cap Value Fund Class I | Financial Services Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	20.00%
Large Cap Value Fund Class I | Healthcare Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	14.10%
Large Cap Value Fund Class I | Energy Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.90%
Large Cap Value Fund Class I | Consumer Discretionary Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.70%
Large Cap Value Fund Class I | Information Technology Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.10%
Large Cap Value Fund Class I | Consumer Staples Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.30%
Large Cap Value Fund Class I | Utilities Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.60%
Large Cap Value Fund Class I | Equity Real Estate Investment Trusts (REITs) [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.80%
Large Cap Value Fund Class I | Communications Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.70%
Large Cap Value Fund Class I | Materials Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.90%
Large Cap Value Fund Class I | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.60%
Large Cap Value Fund Class I | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.00%
Large Cap Value Fund Class II | CME Group, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.30%
Large Cap Value Fund Class II | Automatic Data Processing, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.00%
Large Cap Value Fund Class II | Blackrock, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.90%
Large Cap Value Fund Class II | Morgan Stanley [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.80%
Large Cap Value Fund Class II | Honeywell International, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.80%
Large Cap Value Fund Class II | NextEra Energy, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.50%
Large Cap Value Fund Class II | Home Depot, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.50%
Large Cap Value Fund Class II | Texas Instruments, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.50%
Large Cap Value Fund Class II | Johnson & Johnson [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.30%
Large Cap Value Fund Class II | Fastenal Co. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.30%
Large Cap Value Fund Class II | Industrial Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	20.30%
Large Cap Value Fund Class II | Financial Services Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	20.00%
Large Cap Value Fund Class II | Healthcare Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	14.10%
Large Cap Value Fund Class II | Energy Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.90%
Large Cap Value Fund Class II | Consumer Discretionary Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.70%
Large Cap Value Fund Class II | Information Technology Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.10%
Large Cap Value Fund Class II | Consumer Staples Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.30%
Large Cap Value Fund Class II | Utilities Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.60%
Large Cap Value Fund Class II | Equity Real Estate Investment Trusts (REITs) [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.80%
Large Cap Value Fund Class II | Communications Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.70%
Large Cap Value Fund Class II | Materials Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.90%
Large Cap Value Fund Class II | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.60%
Large Cap Value Fund Class II | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.00%
Large Cap Growth Fund Class I | Texas Instruments, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.00%
Large Cap Growth Fund Class I | Arch Capital Group Ltd. [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.00%
Large Cap Growth Fund Class I | Amazon.com, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.30%
Large Cap Growth Fund Class I | Alphabet, Inc., Class C [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.20%
Large Cap Growth Fund Class I | Ferguson Enterprises, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.60%
Large Cap Growth Fund Class I | Fiserv, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.20%
Large Cap Growth Fund Class I | Visa, Inc., Class A [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.90%
Large Cap Growth Fund Class I | Progressive Corp. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.80%
Large Cap Growth Fund Class I | PACCAR, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.80%
Large Cap Growth Fund Class I | Parker-Hannifin Corp. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.70%
Large Cap Growth Fund Class I | Industrial Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	17.60%
Large Cap Growth Fund Class I | Financial Services Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	26.10%
Large Cap Growth Fund Class I | Healthcare Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	11.70%
Large Cap Growth Fund Class I | Consumer Discretionary Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	15.50%
Large Cap Growth Fund Class I | Information Technology Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	20.00%
Large Cap Growth Fund Class I | Communications Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.10%
Large Cap Growth Fund Class I | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.00%
Large Cap Growth Fund Class I | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.00%
Large Cap Growth Fund Class II | Texas Instruments, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.00%
Large Cap Growth Fund Class II | Arch Capital Group Ltd. [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.00%
Large Cap Growth Fund Class II | Amazon.com, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.30%
Large Cap Growth Fund Class II | Alphabet, Inc., Class C [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.20%
Large Cap Growth Fund Class II | Ferguson Enterprises, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.60%
Large Cap Growth Fund Class II | Fiserv, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.20%
Large Cap Growth Fund Class II | Visa, Inc., Class A [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.90%
Large Cap Growth Fund Class II | Progressive Corp. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.80%
Large Cap Growth Fund Class II | PACCAR, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.80%
Large Cap Growth Fund Class II | Parker-Hannifin Corp. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.70%
Large Cap Growth Fund Class II | Industrial Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	17.60%
Large Cap Growth Fund Class II | Financial Services Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	26.10%
Large Cap Growth Fund Class II | Healthcare Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	11.70%
Large Cap Growth Fund Class II | Consumer Discretionary Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	15.50%
Large Cap Growth Fund Class II | Information Technology Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	20.00%
Large Cap Growth Fund Class II | Communications Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.10%
Large Cap Growth Fund Class II | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.00%
Large Cap Growth Fund Class II | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.00%
Mid Cap Fund Class I | Arch Capital Group Ltd. [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.20%
Mid Cap Fund Class I | PACCAR, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.60%
Mid Cap Fund Class I | Amphenol Corp Class A [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.60%
Mid Cap Fund Class I | Brown And Brown Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.50%
Mid Cap Fund Class I | Gartner Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.20%
Mid Cap Fund Class I | Ross Stores Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.70%
Mid Cap Fund Class I | Carlisle Cos Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.30%
Mid Cap Fund Class I | C D W Corp [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.20%
Mid Cap Fund Class I | Copart Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.70%
Mid Cap Fund Class I | Liberty Media Corp Liberty Formula One Class C [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.40%
Mid Cap Fund Class I | Industrial Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	16.60%
Mid Cap Fund Class I | Financial Services Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	24.10%
Mid Cap Fund Class I | Healthcare Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.00%
Mid Cap Fund Class I | Consumer Discretionary Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	14.30%
Mid Cap Fund Class I | Information Technology Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	26.00%
Mid Cap Fund Class I | Communications Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.50%
Mid Cap Fund Class I | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.60%
Mid Cap Fund Class I | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	(0.10%)
Mid Cap Fund Class II | Arch Capital Group Ltd. [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.20%
Mid Cap Fund Class II | PACCAR, Inc. [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.60%
Mid Cap Fund Class II | Amphenol Corp Class A [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.60%
Mid Cap Fund Class II | Brown And Brown Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.50%
Mid Cap Fund Class II | Gartner Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.20%
Mid Cap Fund Class II | Ross Stores Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.70%
Mid Cap Fund Class II | Carlisle Cos Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.30%
Mid Cap Fund Class II | C D W Corp [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.20%
Mid Cap Fund Class II | Copart Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.70%
Mid Cap Fund Class II | Liberty Media Corp Liberty Formula One Class C [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.40%
Mid Cap Fund Class II | Industrial Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	16.60%
Mid Cap Fund Class II | Financial Services Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	24.10%
Mid Cap Fund Class II | Healthcare Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.00%
Mid Cap Fund Class II | Consumer Discretionary Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	14.30%
Mid Cap Fund Class II | Information Technology Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	26.00%
Mid Cap Fund Class II | Communications Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.50%
Mid Cap Fund Class II | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.60%
Mid Cap Fund Class II | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	(0.10%)
Madison Target Retirement 2020 Fund Class I | Schwab Intermediate Term US Treasury ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	16.50%
Madison Target Retirement 2020 Fund Class I | Janus Henderson Mortgage-Backed Securities ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	24.10%
Madison Target Retirement 2020 Fund Class I | Invesco S&P 500 Quality ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.20%
Madison Target Retirement 2020 Fund Class I | Vanguard Information Technology ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.10%
Madison Target Retirement 2020 Fund Class I | Distillate U.S. Fundamental Stability & Value ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.30%
Madison Target Retirement 2020 Fund Class I | I Shares 7 To 10 Year Treasury Bond E T F [Member]
Holdings [Line Items]
Percent of Net Asset Value	16.80%
Madison Target Retirement 2020 Fund Class I | S P D R Portfolio Short Term Treasury E T F [Member]
Holdings [Line Items]
Percent of Net Asset Value	10.50%
Madison Target Retirement 2020 Fund Class I | I Shares Aaa A Rated Corporate Bond E T F [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.80%
Madison Target Retirement 2020 Fund Class I | iShares MSCI International Quality Factor ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.90%
Madison Target Retirement 2020 Fund Class I | S P D R Portfolio Long Term Treasury E T F [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.60%
Madison Target Retirement 2020 Fund Class I | Exchange Traded Funds [Member]
Holdings [Line Items]
Percent of Net Asset Value	98.10%
Madison Target Retirement 2020 Fund Class I | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.90%
Madison Target Retirement 2020 Fund Class I | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.00%
Madison Target Retirement 2030 Fund Class I | Schwab Intermediate Term US Treasury ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	11.70%
Madison Target Retirement 2030 Fund Class I | Janus Henderson Mortgage-Backed Securities ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	18.60%
Madison Target Retirement 2030 Fund Class I | Invesco S&P 500 Quality ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	10.30%
Madison Target Retirement 2030 Fund Class I | Vanguard Information Technology ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.80%
Madison Target Retirement 2030 Fund Class I | iShares MSCI Emerging Markets Asia ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.40%
Madison Target Retirement 2030 Fund Class I | Distillate U.S. Fundamental Stability & Value ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.00%
Madison Target Retirement 2030 Fund Class I | I Shares 7 To 10 Year Treasury Bond E T F [Member]
Holdings [Line Items]
Percent of Net Asset Value	13.20%
Madison Target Retirement 2030 Fund Class I | S P D R Portfolio Short Term Treasury E T F [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.90%
Madison Target Retirement 2030 Fund Class I | I Shares Aaa A Rated Corporate Bond E T F [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.10%
Madison Target Retirement 2030 Fund Class I | iShares MSCI International Quality Factor ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.60%
Madison Target Retirement 2030 Fund Class I | Exchange Traded Funds [Member]
Holdings [Line Items]
Percent of Net Asset Value	97.00%
Madison Target Retirement 2030 Fund Class I | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.00%
Madison Target Retirement 2030 Fund Class I | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.00%
Madison Target Retirement 2040 Fund Class I | Schwab Intermediate Term US Treasury ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	9.20%
Madison Target Retirement 2040 Fund Class I | Janus Henderson Mortgage-Backed Securities ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	11.00%
Madison Target Retirement 2040 Fund Class I | Invesco S&P 500 Quality ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	15.40%
Madison Target Retirement 2040 Fund Class I | Vanguard Information Technology ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.50%
Madison Target Retirement 2040 Fund Class I | iShares MSCI Emerging Markets Asia ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.10%
Madison Target Retirement 2040 Fund Class I | Distillate U.S. Fundamental Stability & Value ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	12.90%
Madison Target Retirement 2040 Fund Class I | SPDR S&P Bank ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.70%
Madison Target Retirement 2040 Fund Class I | I Shares 7 To 10 Year Treasury Bond E T F [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.90%
Madison Target Retirement 2040 Fund Class I | I Shares Aaa A Rated Corporate Bond E T F [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.50%
Madison Target Retirement 2040 Fund Class I | iShares MSCI International Quality Factor ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.00%
Madison Target Retirement 2040 Fund Class I | Exchange Traded Funds [Member]
Holdings [Line Items]
Percent of Net Asset Value	96.50%
Madison Target Retirement 2040 Fund Class I | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.40%
Madison Target Retirement 2040 Fund Class I | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.10%
Madison Target Retirement 2050 Fund Class I | Schwab Intermediate Term US Treasury ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.80%
Madison Target Retirement 2050 Fund Class I | Janus Henderson Mortgage-Backed Securities ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	8.00%
Madison Target Retirement 2050 Fund Class I | Invesco S&P 500 Quality ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	17.90%
Madison Target Retirement 2050 Fund Class I | Vanguard Information Technology ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.20%
Madison Target Retirement 2050 Fund Class I | iShares MSCI Emerging Markets Asia ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.90%
Madison Target Retirement 2050 Fund Class I | Distillate U.S. Fundamental Stability & Value ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	15.20%
Madison Target Retirement 2050 Fund Class I | SPDR S&P Bank ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.10%
Madison Target Retirement 2050 Fund Class I | I Shares 7 To 10 Year Treasury Bond E T F [Member]
Holdings [Line Items]
Percent of Net Asset Value	6.10%
Madison Target Retirement 2050 Fund Class I | iShares MSCI International Quality Factor ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.70%
Madison Target Retirement 2050 Fund Class I | iShares MSCI Eurozone ETF [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.20%
Madison Target Retirement 2050 Fund Class I | Exchange Traded Funds [Member]
Holdings [Line Items]
Percent of Net Asset Value	96.30%
Madison Target Retirement 2050 Fund Class I | Short-Term Investments [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.60%
Madison Target Retirement 2050 Fund Class I | Other Assets and Liabilities, Net [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.10%