8dd841a75f2cfdb

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-CSR

CERTIFIED SHAREHOLDER REPORT OF REGISTERED MANAGEMENT INVESTMENT COMPANIES

Investment Company Act file number

811-09645

Columbia Funds Series Trust

(Exact name of registrant as specified in charter)

290 Congress Street

Boston, MA 02210

(Address of principal executive offices) (Zip code)

Daniel J. Beckman

c/o Columbia Management Investment Advisers, LLC

290 Congress Street

Boston, MA 02210

Ryan C. Larrenaga, Esq.

c/o Columbia Management Investment Advisers, LLC

290 Congress Street

Boston, MA 02210

(Name and address of agent for service)

Registrant's telephone number, including area code:

(800) 345-6611

Date of fiscal year end:

Last Day of

February

Date of reporting period:

February 28, 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, 100

F Street, NE, Washington, DC 20549. The OMB has reviewed this collection of information under the clearance requirements of 44 U.S.C. § 3507.

Item 1. Reports to Stockholders

Columbia Mid Cap Index Fund

Class A / NTIAX

Annual Shareholder Report | February 28, 2025

This annual shareholder report contains important information about Columbia Mid Cap Index Fund (the Fund) for the period of March 1, 2024 to February 28, 2025. You can find additional information about the Fund at

columbiathreadneedleus.com/resources/literature

. You can also request more information by contacting us at

1-800-345-6611.

What were the Fund costs for the reporting period?

(Based on a hypothetical $10,000 investment)

Class	Cost of a $10,000 investment	Cost paid as a percentage of a $10,000 investment
Class A	$ 47	0.45 %

Management's Discussion of Fund Performance

The performance of Class A shares for the period presented is shown in the Average Annual Total Returns table.

Top Performance Contributors

Sectors

| The financials, utilities and industrials sectors were the top performing sectors within the portfolio, on an absolute basis, over the period.

Individual holdings

| Fund positions in Texas Pacific Land Corporation, a company engaged in land and resource management, and water services and operations in the state of Texas; Vistra Corp., an energy company focused on retail electricity and power generation; Interactive Brokers Group, Inc., an electronic brokerage firm; Williams-Sonoma, Inc., a retail company that sells kitchenware and home furnishings; and Sprouts Farmers Market, Inc., an operator of organic and natural food stores, were among the top absolute contributors during the period.

Top Performance Detractors

Sectors

| The health care, consumer discretionary and materials sectors were the weakest performing sectors within the portfolio on an absolute basis.

Individual holdings

| Fund positions in Celsius Holdings, Inc., a company that produces fitness and energy beverages; elf Beauty, Inc., a provider of cosmetic and skin care products; Five Below, Inc., an operator of specialty discount stores; Avantor, Inc., a biotechnology, chemicals and pharmaceuticals company; and Cleveland-Cliffs, Inc., a mining and natural resources company, were among the top absolute detractors during the period.

Fund Performance

The following shows the change in value of a hypothetical $10,000 investment in Class A shares of the Fund during the stated time period.

Growth of $10,000

Average Annual Total Returns (%)	1 year	5 years	10 years
Class A	8.23	12.51	8.69
S&P MidCap 400® Index	8.69	13.01	9.19
Russell 3000 ® Index (a)	17.53	16.12	12.36

(a)

Effective August 1, 2024, the Fund compares its performance to the Russell 3000

Index, a broad-based performance index as required by new regulatory requirements. The Fund’s performance also continues to be compared to its prior benchmark, which management believes more closely represents the market sectors and/or asset classes in which the Fund primarily invests.

Past performance does not guarantee future performance

. Performance does not reflect the deduction of taxes that a shareholder may pay on fund distributions or on the redemptions of fund shares. Performance results reflect the effect of any fee waivers/expense reimbursements, if applicable. All results shown assume reinvestment of distributions. Visit

columbiathreadneedleus.com/investment-products/mutual-funds

for more recent performance information.

Key Fund Statistics

Fund net assets	$ 2,506,954,643
Total number of portfolio holdings	403
Management services fees (represents 0.20% of Fund average net assets)	$ 5,248,744
Portfolio turnover for the reporting period	16%

Graphical Representation of Fund

Holdings

The tables below show the investment makeup of the Fund represented as a percentage of Fund net assets. Derivatives are excluded from the tables unless otherwise noted. The Fund's portfolio composition is subject to change.

Top Holdings

Williams-Sonoma, Inc.	0.8 %
Interactive Brokers Group, Inc., Class A	0.7 %
Expand Energy Corp.	0.7 %
RB Global, Inc.	0.6 %
EMCOR Group, Inc.	0.6 %
Watsco, Inc.	0.6 %
Equitable Holdings, Inc.	0.6 %
Dynatrace, Inc.	0.6 %
DocuSign, Inc.	0.6 %
Guidewire Software, Inc.	0.6 %

Asset Categories

Graphical Representation - Allocation 1 Chart

Equity Sector Allocation

Graphical Representation - Allocation 2 Chart

Availability of Additional Information

For additional information about the Fund, including its prospectus, financial information, holdings, federal tax information and proxy voting information, visit the Fund’s website included at the beginning of this report or scan the QR code below.

The Fund is distributed by Columbia Management Investment Distributors, Inc., member FINRA, and managed by Columbia Management Investment Advisers, LLC. Columbia Threadneedle Investments (Columbia Threadneedle) is the global brand name of the Columbia and Threadneedle group of companies. All rights reserved.

Not FDIC or NCUA Insured • No Financial Institution Guarantee • May Lose Value

Columbia Mid Cap Index Fund

Institutional Class / NMPAX

Annual Shareholder Report | February 28, 2025

columbiathreadneedleus.com/resources/literature

. You can also request more information by contacting us at

1-800-345-6611.

What were the Fund costs for the reporting period?

(Based on a hypothetical $10,000 investment)

Class	Cost of a $10,000 investment	Cost paid as a percentage of a $10,000 investment
Institutional Class	$ 21	0.20 %

Management's Discussion of Fund Performance

The performance of Institutional Class shares for the period presented is shown in the Average Annual Total Returns table.

Top Performance Contributors

Sectors

| The financials, utilities and industrials sectors were the top performing sectors within the portfolio, on an absolute basis, over the period.

Individual holdings

Top Performance Detractors

Sectors

| The health care, consumer discretionary and materials sectors were the weakest performing sectors within the portfolio on an absolute basis.

Individual holdings

Fund Performance

The following shows the change in value of a hypothetical $10,000 investment in Institutional Class shares of the Fund during the stated time period.

Growth of $10,000

Average Annual Total Returns (%)	1 year	5 years	10 years
Institutional Class	8.48	12.79	8.96
S&P MidCap 400® Index	8.69	13.01	9.19
Russell 3000 ® Index (a)	17.53	16.12	12.36

(a)

Effective August 1, 2024, the Fund compares its performance to the Russell 3000

Past performance does not guarantee future performance

columbiathreadneedleus.com/investment-products/mutual-funds

for more recent performance information.

Key Fund Statistics

Fund net assets	$ 2,506,954,643
Total number of portfolio holdings	403
Management services fees (represents 0.20% of Fund average net assets)	$ 5,248,744
Portfolio turnover for the reporting period	16%

Graphical Representation of Fund

Holdings

Top Holdings

Williams-Sonoma, Inc.	0.8 %
Interactive Brokers Group, Inc., Class A	0.7 %
Expand Energy Corp.	0.7 %
RB Global, Inc.	0.6 %
EMCOR Group, Inc.	0.6 %
Watsco, Inc.	0.6 %
Equitable Holdings, Inc.	0.6 %
Dynatrace, Inc.	0.6 %
DocuSign, Inc.	0.6 %
Guidewire Software, Inc.	0.6 %

Asset Categories

Equity Sector Allocation

Availability of Additional Information

Not FDIC or NCUA Insured • No Financial Institution Guarantee • May Lose Value

Columbia Mid Cap Index Fund

Institutional 2 Class / CPXRX

Annual Shareholder Report | February 28, 2025

columbiathreadneedleus.com/resources/literature

. You can also request more information by contacting us at

1-800-345-6611.

What were the Fund costs for the reporting period?

(Based on a hypothetical $10,000 investment)

Class	Cost of a $10,000 investment	Cost paid as a percentage of a $10,000 investment
Institutional 2 Class	$ 21	0.20 %

Management's Discussion of Fund Performance

The performance of Institutional 2 Class shares for the period presented is shown in the Average Annual Total Returns table.

Top Performance Contributors

Sectors

| The financials, utilities and industrials sectors were the top performing sectors within the portfolio, on an absolute basis, over the period.

Individual holdings

Top Performance Detractors

Sectors

| The health care, consumer discretionary and materials sectors were the weakest performing sectors within the portfolio on an absolute basis.

Individual holdings

Fund Performance

The following shows the change in value of a hypothetical $10,000 investment in Institutional 2 Class shares of the Fund during the stated time period.

Growth of $10,000

Average Annual Total Returns (%)	1 year	5 years	10 years
Institutional 2 Class	8.44	12.78	8.95
S&P MidCap 400® Index	8.69	13.01	9.19
Russell 3000 ® Index (a)	17.53	16.12	12.36

(a)

Effective August 1, 2024, the Fund compares its performance to the Russell 3000

Past performance does not guarantee future performance

columbiathreadneedleus.com/investment-products/mutual-funds

for more recent performance information.

Key Fund Statistics

Fund net assets	$ 2,506,954,643
Total number of portfolio holdings	403
Management services fees (represents 0.20% of Fund average net assets)	$ 5,248,744
Portfolio turnover for the reporting period	16%

Graphical Representation of Fund

Holdings

Top Holdings

Williams-Sonoma, Inc.	0.8 %
Interactive Brokers Group, Inc., Class A	0.7 %
Expand Energy Corp.	0.7 %
RB Global, Inc.	0.6 %
EMCOR Group, Inc.	0.6 %
Watsco, Inc.	0.6 %
Equitable Holdings, Inc.	0.6 %
Dynatrace, Inc.	0.6 %
DocuSign, Inc.	0.6 %
Guidewire Software, Inc.	0.6 %

Asset Categories

Equity Sector Allocation

Availability of Additional Information

Not FDIC or NCUA Insured • No Financial Institution Guarantee • May Lose Value

Columbia Mid Cap Index Fund

Institutional 3 Class / CMDYX

Annual Shareholder Report | February 28, 2025

columbiathreadneedleus.com/resources/literature

. You can also request more information by contacting us at

1-800-345-6611.

What were the Fund costs for the reporting period?

(Based on a hypothetical $10,000 investment)

Class	Cost of a $10,000 investment	Cost paid as a percentage of a $10,000 investment
Institutional 3 Class	$ 21	0.20 %

Management's Discussion of Fund Performance

The performance of Institutional 3 Class shares for the period presented is shown in the Average Annual Total Returns table.

Top Performance Contributors

Sectors

| The financials, utilities and industrials sectors were the top performing sectors within the portfolio, on an absolute basis, over the period.

Individual holdings

Top Performance Detractors

Sectors

| The health care, consumer discretionary and materials sectors were the weakest performing sectors within the portfolio on an absolute basis.

Individual holdings

Fund Performance

The following shows the change in value of a hypothetical $10,000 investment in Institutional 3 Class shares of the Fund during the stated time period.

Growth of $10,000

Average Annual Total Returns (%)	1 year	5 years	10 years
Institutional 3 Class (a)	8.47	12.78	8.95
S&P MidCap 400® Index	8.69	13.01	9.19
Russell 3000 ® Index (b)	17.53	16.12	12.36

(a)	The returns shown for periods prior to March 1, 2017 (including Since Fund Inception returns, if shown) include the returns of Institutional Class. These returns are adjusted to reflect any higher class-related operating expenses of the newer share classes, as applicable. Please visit columbiathreadneedleus.com/investment-products/mutual-funds/appended-performance for more information.
(b)	Effective August 1, 2024, the Fund compares its performance to the Russell 3000 ® Index, a broad-based performance index as required by new regulatory requirements. The Fund’s performance also continues to be compared to its prior benchmark, which management believes more closely represents the market sectors and/or asset classes in which the Fund primarily invests.

Past performance does not guarantee future performance

columbiathreadneedleus.com/investment-products/mutual-funds

for more recent performance information.

Key Fund Statistics

Fund net assets	$ 2,506,954,643
Total number of portfolio holdings	403
Management services fees (represents 0.20% of Fund average net assets)	$ 5,248,744
Portfolio turnover for the reporting period	16%

Graphical Representation of Fund

Holdings

Top Holdings

Williams-Sonoma, Inc.	0.8 %
Interactive Brokers Group, Inc., Class A	0.7 %
Expand Energy Corp.	0.7 %
RB Global, Inc.	0.6 %
EMCOR Group, Inc.	0.6 %
Watsco, Inc.	0.6 %
Equitable Holdings, Inc.	0.6 %
Dynatrace, Inc.	0.6 %
DocuSign, Inc.	0.6 %
Guidewire Software, Inc.	0.6 %

Asset Categories

Equity Sector Allocation

Availability of Additional Information

Not FDIC or NCUA Insured • No Financial Institution Guarantee • May Lose Value

Columbia Mid Cap Index Fund | Class A

ASR196_01_(04/25)

Item 4. Principal Accountant Fees and Services.

The Registrant has engaged its principal accountant to perform audit services, audit-related services, tax services and other services during the past two fiscal years. The following table details the aggregate fees billed or expected to be billed for each of the last two fiscal years for the series of the relevant registrant whose reports to shareholders are included in this annual filing.

	Amount billed to the registrant ($)		Amount billed to the registrant's investment advisor ($)
	February 28, 2025	February 29, 2024	February 28, 2025	February 29, 2024
Audit fees ^(a)	31,523	30,993	0	0
Audit-related fees ^(b)	0	0	0	0
Tax fees ^(c)	14,845	12,850	0	0
All other fees ^(d)	0	0	0	0
Non-audit fees ^(g)	0	0	587,000	581,000

(a) Audit Fees include amounts related to the audit of the registrant’s annual financial statements or services that are normally provided by the accountant in connection with statutory and regulatory filings or engagements for those fiscal years.

(b) Audit-Related Fees include amounts for assurance and related services by the principal accountant that are reasonably related to the performance of the audit of the registrant’s financial statements and are not reported in Audit Fees above.

(c) Tax Fees include amounts for the review of annual tax returns, the review of required shareholder distribution calculations and typically include amounts for professional services by the principal accountant for tax compliance, tax advice, tax planning and foreign tax filings, if applicable.

(d) All Other Fees include amounts for products and services provided by the principal accountant, other than the services reported in paragraphs (a) through (c) above and typically include SOC-1 reviews.

(e)(1) Audit Committee Pre-Approval Policies and Procedures
The registrant’s Audit Committee is required to pre-approve the engagement of the registrant’s independent auditors to provide audit and non-audit services to the registrant and non-audit services to its investment adviser (excluding any sub-adviser whose role is primarily portfolio management and is sub-contracted or overseen by another investment adviser (the “Adviser”) or any entity controlling, controlled by or under common control with the Adviser that provides ongoing services to the Fund (a “Control Affiliate”) if the engagement relates directly to the operations and financial reporting of the registrant.

The Audit Committee has adopted a Policy for Engagement of Independent Auditors for Audit and Non-Audit Services (the “Policy”). The Policy sets forth the understanding of the Audit Committee regarding the engagement of the registrant’s independent accountants to provide (i) audit and permissible audit-related, tax and other services to the registrant (“Fund Services”); (ii) non-audit services to the registrant’s Adviser and any Control Affiliates, that relates directly to the operations and financial reporting of a Fund (“Fund-related Adviser Services”); and (iii) certain other audit and non-audit services to the registrant’s Adviser and its Control Affiliates. A service will require specific pre-approval by the Audit Committee if it is to be provided by the Fund’s independent auditor; provided, however, that pre-approval of non-audit services to the Fund, the Adviser or Control Affiliates may be waived if certain de minimis requirements set forth in the SEC’s rules are met.

Under the Policy, the Audit Committee may delegate pre-approval authority to any pre-designated member or members who are independent board members. The member(s) to whom such authority is delegated must report, for informational purposes only, any pre-approval decisions to the Audit Committee at its next regular meeting. The Audit Committee's responsibilities with respect to the pre-approval of services performed by the independent auditor may not be delegated to management.

On an annual basis, at a regularly scheduled Audit Committee meeting, the Fund’s Treasurer or other Fund officer shall submit to the Audit Committee a schedule of the types of Fund Services and Fund-related Adviser Services that are subject to specific pre-approval. This schedule will provide a description of each type of service that is subject to specific pre-approval, along with total projected fees for each service. The pre-approval will generally cover a one-year period. The Audit Committee will review and approve the types of services and the projected fees for the next one-year period and may add to, or subtract from, the list of pre-approved services from time to time, based on subsequent determinations. This specific approval acknowledges that the Audit Committee is in agreement with the specific types of services that the independent auditor will be permitted to perform and the projected fees for each service.

The Fund’s Treasurer or other Fund officer shall report to the Audit Committee at each of its regular meetings regarding all Fund Services or Fund-related Adviser Services provided since the last such report was rendered, including a description of the services, by category, with forecasted fees for the annual reporting period, proposed changes requiring specific pre-approval and a description of services provided by the independent auditor, by category, with actual fees during the current reporting period.

(e)(2) None, or 0%, of the Audit-Related Fees, Tax Fees and All Other Fees paid by the Fund or affiliated entities relating directly to the operations and financial reporting of the Registrant disclosed above were approved by the audit committee pursuant to paragraphs (c)(7)(i)(C) of Rule 2-01 of Regulation S-X (which permits audit committee approval after the start of the engagement with respect to services other than audit, review or attest services, if certain conditions are satisfied).

(f) Not applicable.

(g) The aggregate non-audit fees billed by the registrant’s accountant for services rendered to the registrant and rendered to the registrant’s investment adviser (not including any sub-adviser whose role is primarily portfolio management and is subcontracted with or overseen by another investment adviser), and any entity controlling, controlled by, or under common control with the adviser that provides ongoing services to the registrant.

(h) The registrant’s Audit Committee of the Board of Directors has considered whether the provision of non-audit services that were rendered to the registrant’s adviser (not including any sub-adviser whose role is primarily portfolio management and is subcontracted with or overseen by another investment adviser), and any entity controlling, controlled by, or under common control with the investment adviser that provides ongoing services to the registrant that were not pre-approved pursuant to paragraph (c)(7)(ii) of Rule 2-01 of Regulation S-X, is compatible with maintaining the principal accountant’s independence.

(i) Not applicable.

(j) Not applicable.

Portfolio of Investments

February 28, 2025

(Percentages represent value of investments compared to net assets)

Investments in securities

Common Stocks 98.2%
Issuer	Shares	Value ($)
Communication Services 1.4%
Diversified Telecommunication Services 0.4%
Frontier Communications Parent, Inc.(a)	187,358	6,743,014
Iridium Communications, Inc.	96,246	3,037,524
Total		9,780,538
Entertainment 0.5%
TKO Group Holdings, Inc.(a)	56,255	8,474,253
Warner Music Group Corp., Class A	119,711	4,034,261
Total		12,508,514
Interactive Media & Services 0.1%
ZoomInfo Technologies, Inc.(a)	229,322	2,673,895
Media 0.4%
New York Times Co. (The), Class A	137,946	6,633,823
Nexstar Media Group, Inc., Class A	24,652	4,169,886
Total		10,803,709
Total Communication Services		35,766,656
Consumer Discretionary 13.4%
Automobile Components 0.8%
Autoliv, Inc.	61,250	5,962,687
Gentex Corp.	192,269	4,675,982
Goodyear Tire & Rubber Co. (The)(a)	240,868	2,276,203
Lear Corp.	45,939	4,317,807
Visteon Corp.(a)	23,349	2,024,825
Total		19,257,504
Automobiles 0.3%
Harley-Davidson, Inc.	96,877	2,495,551
Thor Industries, Inc.	44,892	4,461,816
Total		6,957,367
Broadline Retail 0.4%
Macy’s, Inc.	234,488	3,364,903
Nordstrom, Inc.	81,905	1,989,472
Ollie’s Bargain Outlet Holdings, Inc.(a)	51,863	5,368,339
Total		10,722,714

Common Stocks (continued)
Issuer	Shares	Value ($)
Diversified Consumer Services 1.3%
Duolingo, Inc.(a)	32,038	9,998,099
Graham Holdings Co., Class B	2,849	2,802,761
Grand Canyon Education, Inc.(a)	24,299	4,369,446
H&R Block, Inc.	115,857	6,315,365
Service Corp. International	122,268	9,903,708
Total		33,389,379
Hotels, Restaurants & Leisure 3.2%
Aramark	222,717	8,251,665
Boyd Gaming Corp.	56,042	4,273,763
Choice Hotels International, Inc.	18,887	2,706,318
Churchill Downs, Inc.	62,134	7,362,879
Hilton Grand Vacations, Inc.(a)	52,455	2,250,320
Hyatt Hotels Corp., Class A	35,752	5,039,244
Light & Wonder, Inc.(a)	74,655	8,322,539
Marriott Vacations Worldwide Corp.	27,152	2,048,347
Planet Fitness, Inc., Class A(a)	71,166	6,586,413
Texas Roadhouse, Inc.	56,399	10,382,492
Travel + Leisure Co.	57,829	3,228,015
Vail Resorts, Inc.	31,670	5,035,213
Wendy’s Co. (The)	144,756	2,243,718
Wingstop, Inc.	24,696	5,798,127
Wyndham Hotels & Resorts, Inc.	65,762	7,123,998
Total		80,653,051
Household Durables 1.6%
KB Home	59,545	3,632,245
Somnigroup International, Inc.	146,801	9,377,648
Taylor Morrison Home Corp., Class A(a)	87,479	5,392,206
Toll Brothers, Inc.	85,361	9,529,702
TopBuild Corp.(a)	24,788	7,594,795
Whirlpool Corp.	46,615	4,744,941
Total		40,271,537

The accompanying Notes to Financial Statements are an integral part of this statement.

Columbia Mid Cap Index Fund | 2025

Portfolio of Investments (continued)

February 28, 2025

Common Stocks (continued)
Issuer	Shares	Value ($)
Leisure Products 0.5%
Brunswick Corp.	55,781	3,394,274
Mattel, Inc.(a)	284,812	6,066,496
Polaris, Inc.	44,319	1,990,809
YETI Holdings, Inc.(a)	71,710	2,555,744
Total		14,007,323
Specialty Retail 4.4%
Abercrombie & Fitch Co., Class A(a)	43,182	4,447,314
AutoNation, Inc.(a)	22,121	4,034,207
Burlington Stores, Inc.(a)	53,243	13,275,077
Chewy, Inc., Class A(a)	139,341	5,191,846
Dick’s Sporting Goods, Inc.	48,899	11,007,165
Five Below, Inc.(a)	46,501	4,040,472
Floor & Decor Holdings, Inc., Class A(a)	90,652	8,759,703
GameStop Corp., Class A(a)	343,502	8,601,290
Gap, Inc. (The)	187,699	4,243,874
Lithia Motors, Inc., Class A	22,519	7,756,444
Murphy U.S.A., Inc.	15,578	7,309,821
Penske Automotive Group, Inc.	15,805	2,666,778
Restoration Hardware Holdings, Inc.(a)	12,657	4,076,440
Valvoline, Inc.(a)	108,942	4,017,781
Williams-Sonoma, Inc.	106,806	20,782,311
Total		110,210,523
Textiles, Apparel & Luxury Goods 0.9%
Capri Holdings Ltd.(a)	99,666	2,190,659
Columbia Sportswear Co.	27,077	2,351,367
Crocs, Inc.(a)	49,271	4,905,913
PVH Corp.	47,185	3,531,325
Skechers U.S.A., Inc., Class A(a)	111,247	6,784,955
Under Armour, Inc., Class A(a)	159,628	1,087,067
Under Armour, Inc., Class C(a)	109,606	695,998
Total		21,547,284
Total Consumer Discretionary		337,016,682

Common Stocks (continued)
Issuer	Shares	Value ($)
Consumer Staples 4.7%
Beverages 0.5%
Boston Beer Co., Inc. (The), Class A(a)	7,274	1,773,183
Celsius Holdings, Inc.(a)	133,124	3,419,955
Coca-Cola Bottling Co. Consolidated	4,983	7,061,509
Total		12,254,647
Consumer Staples Distribution & Retail 2.7%
BJ’s Wholesale Club Holdings, Inc.(a)	112,087	11,349,930
Casey’s General Stores, Inc.	31,377	12,996,667
Maplebear, Inc.(a)	136,821	5,621,975
Performance Food Group, Inc.(a)	131,716	11,214,300
Sprouts Farmers Market, Inc.(a)	84,531	12,544,401
U.S. Foods Holding Corp.(a)	196,924	14,115,512
Total		67,842,785
Food Products 1.0%
Darling Ingredients, Inc.(a)	134,457	4,852,553
Flowers Foods, Inc.	165,575	3,102,876
Ingredion, Inc.	55,084	7,194,521
Lancaster Colony Corp.	16,313	3,118,312
Pilgrim’s Pride Corp.(a)	34,078	1,853,502
Post Holdings, Inc.(a)	40,027	4,543,465
Total		24,665,229
Personal Care Products 0.5%
BellRing Brands, Inc.(a)	109,260	8,006,573
Coty, Inc., Class A(a)	308,869	1,757,465
elf Beauty, Inc.(a)	47,622	3,345,445
Total		13,109,483
Total Consumer Staples		117,872,144
Energy 4.5%
Energy Equipment & Services 0.6%
ChampionX Corp.	161,047	4,799,201
NOV, Inc.	328,927	4,907,591
Valaris Ltd.(a)	55,313	1,974,674
Weatherford International PLC	61,419	3,802,450
Total		15,483,916

The accompanying Notes to Financial Statements are an integral part of this statement.

Columbia Mid Cap Index Fund | 2025

Portfolio of Investments (continued)

February 28, 2025

Common Stocks (continued)
Issuer	Shares	Value ($)
Oil, Gas & Consumable Fuels 3.9%
Antero Midstream Corp.	284,834	4,827,936
Antero Resources Corp.(a)	247,271	9,074,846
Chord Energy Corp.	51,679	5,906,910
Civitas Resources, Inc.	75,065	2,877,992
CNX Resources Corp.(a)	126,192	3,646,949
DT Midstream, Inc.	82,135	7,892,352
Expand Energy Corp.	177,736	17,574,536
HF Sinclair Corp.	135,202	4,768,575
Matador Resources Co.	98,098	5,134,449
Murphy Oil Corp.	115,896	3,070,085
Ovintiv, Inc.	220,075	9,564,459
PBF Energy, Inc., Class A	82,725	1,772,797
Permian Resources Corp.	537,993	7,580,321
Range Resources Corp.	204,001	7,572,517
Viper Energy, Inc.	107,849	5,022,528
Total		96,287,252
Total Energy		111,771,168
Financials 18.3%
Banks 6.8%
Associated Banc-Corp.	136,038	3,380,544
Bank OZK	89,193	4,282,156
Cadence Bank	154,679	5,129,156
Columbia Banking System, Inc.	177,135	4,734,818
Comerica, Inc.	111,181	7,152,274
Commerce Bancshares, Inc.	103,578	6,737,749
Cullen/Frost Bankers, Inc.	54,217	7,429,355
East West Bancorp, Inc.	117,195	11,066,724
First Financial Bankshares, Inc.	108,733	4,094,885
First Horizon Corp.	448,173	9,653,646
Flagstar Financial, Inc.	256,182	3,074,184
FNB Corp.	303,990	4,511,212
Glacier Bancorp, Inc.	95,865	4,682,047
Hancock Whitney Corp.	72,754	4,156,436
Home Bancshares, Inc.	156,297	4,681,095
International Bancshares Corp.	45,224	3,030,008
Old National Bancorp	269,656	6,404,330
Pinnacle Financial Partners, Inc.	64,700	7,392,622
Prosperity Bancshares, Inc.	80,536	6,181,943

Common Stocks (continued)
Issuer	Shares	Value ($)
SouthState Corp.	82,950	8,361,360
Synovus Financial Corp.	119,762	6,213,253
Texas Capital Bancshares, Inc.(a)	39,067	3,092,544
UMB Financial Corp.	57,468	6,340,444
United Bankshares, Inc.	114,046	4,121,622
Valley National Bancorp	401,375	3,949,530
Webster Financial Corp.	144,908	8,161,219
Western Alliance Bancorp	92,206	8,014,545
Wintrust Financial Corp.	56,212	6,996,708
Zions Bancorp	124,873	6,748,137
Total		169,774,546
Capital Markets 3.7%
Affiliated Managers Group, Inc.	25,552	4,365,559
Carlyle Group, Inc. (The)	178,404	8,891,656
Evercore, Inc., Class A	29,930	7,237,074
Federated Hermes, Inc., Class B	65,871	2,552,501
Hamilton Lane, Inc., Class A	35,312	5,519,972
Houlihan Lokey, Inc., Class A	45,301	7,852,928
Interactive Brokers Group, Inc., Class A	92,045	18,813,998
Janus Henderson Group PLC	107,530	4,537,766
Jefferies Financial Group, Inc.	137,244	9,085,553
Morningstar, Inc.	22,840	7,165,365
SEI Investments Co.	82,824	6,630,061
Stifel Financial Corp.	86,528	9,188,408
Total		91,840,841
Consumer Finance 0.7%
Ally Financial, Inc.	231,843	8,601,375
FirstCash Holdings, Inc.	32,915	3,695,696
SLM Corp.	179,502	5,419,166
Total		17,716,237
Financial Services 1.9%
Equitable Holdings, Inc.	264,892	14,574,358
Essent Group Ltd.	89,791	5,173,757
Euronet Worldwide, Inc.(a)	34,911	3,576,981
MGIC Investment Corp.	214,192	5,271,265
Shift4 Payments, Inc., Class A(a)	58,049	5,732,339
Voya Financial, Inc.	81,342	5,877,773

The accompanying Notes to Financial Statements are an integral part of this statement.

Columbia Mid Cap Index Fund | 2025

Portfolio of Investments (continued)

February 28, 2025

Common Stocks (continued)
Issuer	Shares	Value ($)
Western Union Co. (The)	285,573	3,092,756
WEX, Inc.(a)	33,632	5,283,587
Total		48,582,816
Insurance 4.6%
American Financial Group, Inc.	61,021	7,705,732
Brighthouse Financial, Inc.(a)	50,177	2,975,998
CNO Financial Group, Inc.	87,252	3,637,536
Fidelity National Financial, Inc.	219,765	14,181,435
First American Financial Corp.	87,078	5,720,154
Hanover Insurance Group, Inc. (The)	30,462	5,194,685
Kemper Corp.	50,894	3,439,416
Kinsale Capital Group, Inc.	18,703	8,076,891
Old Republic International Corp.	197,206	7,594,403
Primerica, Inc.	28,211	8,181,190
Reinsurance Group of America, Inc.	55,681	11,285,982
RenaissanceRe Holdings Ltd.	43,910	10,433,894
RLI Corp.	70,501	5,364,421
Ryan Specialty Holdings, Inc., Class A	89,946	6,295,320
Selective Insurance Group, Inc.	51,395	4,422,283
Unum Group	142,028	11,687,484
Total		116,196,824
Mortgage Real Estate Investment Trusts (REITS) 0.6%
Annaly Capital Management, Inc.	473,881	10,406,427
Starwood Property Trust, Inc.	270,779	5,556,385
Total		15,962,812
Total Financials		460,074,076
Health Care 8.9%
Biotechnology 2.7%
BioMarin Pharmaceutical, Inc.(a)	161,117	11,465,086
Cytokinetics, Inc.(a)	99,768	4,589,328
Exelixis, Inc.(a)	241,425	9,340,733
Halozyme Therapeutics, Inc.(a)	107,556	6,361,938
Neurocrine Biosciences, Inc.(a)	85,593	10,161,601
Roivant Sciences Ltd.(a)	363,087	3,899,554
Sarepta Therapeutics, Inc.(a)	80,752	8,620,276
United Therapeutics Corp.(a)	37,742	12,079,327
Total		66,517,843

Common Stocks (continued)
Issuer	Shares	Value ($)
Health Care Equipment & Supplies 1.7%
Dentsply Sirona, Inc.	168,046	2,781,161
Envista Holdings Corp.(a)	145,489	2,906,870
Globus Medical, Inc., Class A(a)	96,152	7,722,929
Haemonetics Corp.(a)	42,459	2,781,065
Lantheus Holdings, Inc.(a)	58,777	5,514,458
LivaNova PLC(a)	45,905	1,911,025
Masimo Corp.(a)	37,568	7,091,711
Neogen Corp.(a)	166,707	1,675,405
Penumbra, Inc.(a)	32,445	9,261,101
Total		41,645,725
Health Care Providers & Services 2.0%
Acadia Healthcare Co., Inc.(a)	78,524	2,354,150
Amedisys, Inc.(a)	27,687	2,547,204
Chemed Corp.	12,666	7,609,733
Encompass Health Corp.	85,173	8,529,224
Ensign Group, Inc. (The)	48,106	6,212,890
HealthEquity, Inc.(a)	73,823	8,102,812
Option Care Health, Inc.(a)	143,869	4,819,612
Tenet Healthcare Corp.(a)	80,394	10,177,076
Total		50,352,701
Health Care Technology 0.3%
Doximity, Inc., Class A(a)	108,325	7,636,913
Life Sciences Tools & Services 1.8%
Avantor, Inc.(a)	575,384	9,608,913
Bio-Rad Laboratories, Inc., Class A(a)	16,278	4,316,275
Bruker Corp.	93,556	4,417,714
Illumina, Inc.(a)	134,079	11,898,170
Medpace Holdings, Inc.(a)	21,547	7,052,764
Repligen Corp.(a)	44,033	7,012,696
Sotera Health Co.(a)	129,302	1,612,396
Total		45,918,928
Pharmaceuticals 0.4%
Jazz Pharmaceuticals PLC(a)	51,108	7,335,531
Perrigo Co. PLC	115,335	3,344,715
Total		10,680,246
Total Health Care		222,752,356

The accompanying Notes to Financial Statements are an integral part of this statement.

Columbia Mid Cap Index Fund | 2025

Portfolio of Investments (continued)

February 28, 2025

Common Stocks (continued)
Issuer	Shares	Value ($)
Industrials 20.5%
Aerospace & Defense 1.3%
BWX Technologies, Inc.	77,306	8,037,505
Curtiss-Wright Corp.	32,081	10,319,174
Hexcel Corp.	68,478	4,339,451
Woodward, Inc.	50,435	9,531,963
Total		32,228,093
Air Freight & Logistics 0.2%
GXO Logistics, Inc.(a)	101,010	3,981,814
Building Products 2.4%
AAON, Inc.	57,032	4,380,057
Advanced Drainage Systems, Inc.	59,649	6,644,302
Carlisle Companies, Inc.	38,212	13,021,121
Fortune Brands Innovations, Inc.	105,019	6,796,830
Owens Corning	72,521	11,171,135
Simpson Manufacturing Co., Inc.	35,645	5,860,038
Trex Company, Inc.(a)	90,578	5,587,757
UFP Industries, Inc.	51,336	5,492,952
Total		58,954,192
Commercial Services & Supplies 1.6%
Brink’s Co. (The)	36,895	3,469,606
Clean Harbors, Inc.(a)	42,832	9,146,773
MSA Safety, Inc.	33,232	5,440,078
RB Global, Inc.	155,902	15,961,247
Tetra Tech, Inc.	226,325	6,606,427
Total		40,624,131
Construction & Engineering 2.3%
AECOM	113,339	11,339,567
Comfort Systems U.S.A., Inc.	29,994	10,897,720
EMCOR Group, Inc.	38,890	15,902,510
Fluor Corp.(a)	144,998	5,514,274
MasTec, Inc.(a)	52,046	6,796,687
Valmont Industries, Inc.	16,937	5,900,343
Total		56,351,101

Common Stocks (continued)
Issuer	Shares	Value ($)
Electrical Equipment 1.4%
Acuity Brands, Inc.	25,838	7,677,245
EnerSys	33,663	3,416,458
NEXTracker, Inc., Class A(a)	121,432	5,345,437
nVent Electric PLC	139,334	8,407,413
Regal Rexnord Corp.	55,988	7,244,847
Sensata Technologies Holding	126,441	3,647,823
Total		35,739,223
Ground Transportation 1.6%
Avis Budget Group, Inc.(a)	14,259	1,126,604
Knight-Swift Transportation Holdings, Inc.	136,863	6,903,370
Landstar System, Inc.	29,868	4,743,038
Ryder System, Inc.	35,752	5,880,131
Saia, Inc.(a)	22,483	9,205,439
XPO, Inc.(a)	98,405	12,099,879
Total		39,958,461
Machinery 5.1%
AGCO Corp.	52,377	5,078,998
Chart Industries, Inc.(a)	35,549	6,773,862
CNH Industrial NV	739,114	9,519,788
Crane Co.	41,126	6,703,127
Donaldson Co., Inc.	101,235	6,994,326
Esab Corp.	48,036	6,018,911
Flowserve Corp.	111,064	6,112,963
Graco, Inc.	142,744	12,428,720
ITT, Inc.	68,899	9,731,295
Lincoln Electric Holdings, Inc.	47,702	9,859,526
Middleby Corp. (The)(a)	45,476	7,522,185
Mueller Industries, Inc.	96,150	7,709,307
Oshkosh Corp.	55,005	5,627,012
RBC Bearings, Inc.(a)	26,407	9,485,394
Terex Corp.	56,472	2,298,410
Timken Co. (The)	53,941	4,369,221
Toro Co. (The)	86,750	6,958,218
Watts Water Technologies, Inc., Class A	23,147	4,966,883
Total		128,158,146
Marine Transportation 0.2%
Kirby Corp.(a)	48,525	5,057,276

The accompanying Notes to Financial Statements are an integral part of this statement.

Columbia Mid Cap Index Fund | 2025

Portfolio of Investments (continued)

February 28, 2025

Common Stocks (continued)
Issuer	Shares	Value ($)
Passenger Airlines 0.3%
American Airlines Group, Inc.(a)	555,532	7,971,884
Professional Services 2.3%
CACI International, Inc., Class A(a)	18,943	6,343,063
Concentrix Corp.	39,454	1,781,743
ExlService Holdings, Inc.(a)	136,008	6,589,588
Exponent, Inc.	42,915	3,633,184
FTI Consulting, Inc.(a)	29,863	4,945,313
Genpact Ltd.	137,166	7,299,974
Insperity, Inc.	30,023	2,641,123
KBR, Inc.	112,641	5,522,788
ManpowerGroup, Inc.	39,679	2,286,701
MAXIMUS, Inc.	50,873	3,316,920
Parsons Corp.(a)	39,500	2,299,690
Paylocity Holding Corp.(a)	36,760	7,509,700
Science Applications International Corp.	41,864	4,135,745
Total		58,305,532
Trading Companies & Distributors 1.8%
Applied Industrial Technologies, Inc.	32,503	8,144,602
Core & Main, Inc., Class A(a)	162,862	8,307,591
GATX Corp.	30,044	5,018,850
MSC Industrial Direct Co., Inc., Class A	37,809	3,038,331
Watsco, Inc.	29,445	14,849,997
WESCO International, Inc.	37,697	6,803,177
Total		46,162,548
Total Industrials		513,492,401
Information Technology 10.3%
Communications Equipment 0.5%
Ciena Corp.(a)	122,097	9,715,258
Lumentum Holdings, Inc.(a)	58,078	4,084,626
Total		13,799,884
Electronic Equipment, Instruments & Components 2.9%
Arrow Electronics, Inc.(a)	44,459	4,804,684
Avnet, Inc.	73,499	3,714,639
Belden, Inc.	34,100	3,752,023
Cognex Corp.	144,997	4,755,902
Coherent Corp.(a)	130,751	9,831,168
Crane NXT Co.	41,570	2,320,437

Common Stocks (continued)
Issuer	Shares	Value ($)
Fabrinet(a)	30,661	6,133,733
Flex Ltd.(a)	327,828	12,421,403
IPG Photonics Corp.(a)	22,668	1,319,051
Littelfuse, Inc.	20,978	4,869,203
Novanta, Inc.(a)	30,367	4,392,283
TD SYNNEX Corp.	64,020	8,802,110
Vontier Corp.	126,977	4,742,591
Total		71,859,227
IT Services 0.4%
ASGN, Inc.(a)	37,366	2,517,721
Kyndryl Holdings, Inc.(a)	196,359	7,477,351
Total		9,995,072
Semiconductors & Semiconductor Equipment 2.1%
Allegro MicroSystems, Inc.(a)	110,432	2,462,634
Amkor Technology, Inc.	95,910	2,023,701
Cirrus Logic, Inc.(a)	44,924	4,681,530
Lattice Semiconductor Corp.(a)	116,639	7,271,275
MACOM Technology Solutions Holdings, Inc.(a)	48,965	5,663,292
MKS Instruments, Inc.	56,894	5,224,007
Onto Innovation, Inc.(a)	41,755	6,082,033
Power Integrations, Inc.	48,073	2,922,839
Rambus, Inc.(a)	90,097	5,035,521
Silicon Laboratories, Inc.(a)	27,431	3,848,569
Synaptics, Inc.(a)	33,865	2,239,831
Universal Display Corp.	37,314	5,732,177
Total		53,187,409
Software 3.8%
Altair Engineering, Inc., Class A(a)	50,535	5,639,706
Appfolio, Inc., Class A(a)	19,512	4,185,324
Aspen Technology, Inc.(a)	22,458	5,956,984
BILL Holdings, Inc.(a)	80,496	4,443,379
Blackbaud, Inc.(a)	33,136	2,190,290
CommVault Systems, Inc.(a)	36,965	6,304,750
DocuSign, Inc.(a)	171,591	14,271,223
Dolby Laboratories, Inc., Class A	50,450	4,117,225
Dropbox, Inc., Class A(a)	188,174	4,888,761
Dynatrace, Inc.(a)	252,335	14,446,179
Guidewire Software, Inc.(a)	70,606	14,214,400

The accompanying Notes to Financial Statements are an integral part of this statement.

Columbia Mid Cap Index Fund | 2025

Portfolio of Investments (continued)

February 28, 2025

Common Stocks (continued)
Issuer	Shares	Value ($)
Manhattan Associates, Inc.(a)	51,632	9,132,668
Qualys, Inc.(a)	30,933	4,066,452
Teradata Corp.(a)	80,904	1,928,751
Total		95,786,092
Technology Hardware, Storage & Peripherals 0.6%
Pure Storage, Inc., Class A(a)	263,176	13,808,845
Total Information Technology		258,436,529
Materials 6.4%
Chemicals 2.0%
Arcadium Lithium PLC(a)	909,326	5,310,464
Ashland, Inc.	41,282	2,510,771
Avient Corp.	77,238	3,303,469
Axalta Coating Systems Ltd.(a)	184,348	6,675,241
Cabot Corp.	46,348	3,985,928
Chemours Co. LLC (The)	126,310	1,888,335
NewMarket Corp.	6,489	3,699,444
Olin Corp.	98,569	2,502,667
RPM International, Inc.	108,804	13,479,728
Scotts Miracle-Gro Co. (The), Class A	36,027	2,110,101
Westlake Corp.	28,290	3,176,967
Total		48,643,115
Construction Materials 0.4%
Eagle Materials, Inc.	28,357	6,414,637
Knife River Corp.(a)	47,860	4,579,245
Total		10,993,882
Containers & Packaging 1.6%
AptarGroup, Inc.	56,255	8,255,421
Berry Global Group, Inc.	96,882	6,991,974
Crown Holdings, Inc.	99,915	8,955,381
Graphic Packaging Holding Co.	253,735	6,769,650
Greif, Inc., Class A	21,852	1,251,245
Silgan Holdings, Inc.	68,615	3,726,481
Sonoco Products Co.	83,069	3,972,360
Total		39,922,512

Common Stocks (continued)
Issuer	Shares	Value ($)
Metals & Mining 2.2%
Alcoa Corp.	218,411	7,262,166
Carpenter Technology Corp.	42,138	8,725,516
Cleveland-Cliffs, Inc.(a)	409,223	4,435,977
Commercial Metals Co.	96,298	4,664,675
Reliance, Inc.	45,752	13,595,664
Royal Gold, Inc.	55,590	8,171,730
United States Steel Corp.	190,357	7,656,159
Total		54,511,887
Paper & Forest Products 0.2%
Louisiana-Pacific Corp.	52,847	5,267,260
Total Materials		159,338,656
Real Estate 7.0%
Diversified REITs 0.5%
WP Carey, Inc.	185,012	11,879,620
Health Care REITs 0.7%
Healthcare Realty Trust, Inc.	299,596	5,132,080
Omega Healthcare Investors, Inc.	228,211	8,407,293
Sabra Health Care REIT, Inc.	200,008	3,322,133
Total		16,861,506
Hotel & Resort REITs 0.1%
Park Hotels & Resorts, Inc.	174,493	2,142,774
Industrial REITs 1.1%
EastGroup Properties, Inc.	41,783	7,640,021
First Industrial Realty Trust, Inc.	111,886	6,386,453
Rexford Industrial Realty, Inc.	187,665	7,754,318
STAG Industrial, Inc.	154,040	5,542,359
Total		27,323,151
Office REITs 0.6%
COPT Defense Properties	95,077	2,569,932
Cousins Properties, Inc.	141,434	4,289,693
Kilroy Realty Corp.	89,816	3,206,431
Vornado Realty Trust	140,220	5,894,849
Total		15,960,905
Real Estate Management & Development 0.4%
Jones Lang LaSalle, Inc.(a)	40,109	10,905,236

The accompanying Notes to Financial Statements are an integral part of this statement.

Columbia Mid Cap Index Fund | 2025

Portfolio of Investments (continued)

February 28, 2025

Common Stocks (continued)
Issuer	Shares	Value ($)
Residential REITs 1.0%
American Homes 4 Rent, Class A	268,183	9,925,453
Equity LifeStyle Properties, Inc.	161,511	11,076,424
Independence Realty Trust, Inc.	189,982	4,141,608
Total		25,143,485
Retail REITs 1.0%
Agree Realty Corp.	87,329	6,444,880
Brixmor Property Group, Inc.	255,361	7,139,894
Kite Realty Group Trust	185,703	4,258,170
NNN REIT, Inc.	158,532	6,729,683
Total		24,572,627
Specialized REITs 1.6%
CubeSmart	191,187	7,892,199
EPR Properties	64,022	3,397,648
Gaming and Leisure Properties, Inc.	231,968	11,633,195
Lamar Advertising Co., Class A	74,342	9,235,507
National Storage Affiliates Trust	59,299	2,290,127
PotlatchDeltic Corp.	60,593	2,813,333
Rayonier, Inc.	113,374	3,003,277
Total		40,265,286
Total Real Estate		175,054,590
Utilities 2.8%
Electric Utilities 1.0%
Allete, Inc.	48,880	3,210,927
IDACORP, Inc.	45,034	5,309,959
OGE Energy Corp.	169,879	7,862,000
Portland General Electric Co.	89,151	3,996,639
TXNM Energy, Inc.	76,254	3,984,272
Total		24,363,797

Common Stocks (continued)
Issuer	Shares	Value ($)
Gas Utilities 1.1%
National Fuel Gas Co.	77,232	5,807,847
New Jersey Resources Corp.	83,836	4,055,986
ONE Gas, Inc.	47,896	3,599,384
Southwest Gas Holdings, Inc.	50,947	3,823,572
Spire, Inc.	48,821	3,752,382
UGI Corp.	181,496	6,199,903
Total		27,239,074
Independent Power and Renewable Electricity Producers 0.1%
Ormat Technologies, Inc.	48,570	3,392,129
Multi-Utilities 0.3%
Black Hills Corp.	60,507	3,701,818
Northwestern Energy Group, Inc.	51,834	2,899,076
Total		6,600,894
Water Utilities 0.3%
Essential Utilities, Inc.	213,581	8,111,806
Total Utilities		69,707,700
Total Common Stocks (Cost $1,542,204,683)		2,461,282,958

Money Market Funds 1.2%
	Shares	Value ($)
Columbia Short-Term Cash Fund, 4.479%(b),(c)	29,585,027	29,582,068
Total Money Market Funds (Cost $29,579,576)		29,582,068
Total Investments in Securities (Cost: $1,571,784,259)		2,490,865,026
Other Assets & Liabilities, Net		16,089,617
Net Assets		2,506,954,643

At February 28, 2025, securities and/or cash totaling $3,323,775 were pledged as collateral.

Investments in derivatives

Long futures contracts
Description	Number of contracts	Expiration date	Trading currency	Notional amount	Value/Unrealized appreciation ($)	Value/Unrealized depreciation ($)
S&P Mid 400 Index E-mini	147	03/2025	USD	45,565,590	—	(1,282,272 )

The accompanying Notes to Financial Statements are an integral part of this statement.

Columbia Mid Cap Index Fund | 2025

Portfolio of Investments (continued)

February 28, 2025

Notes to Portfolio of Investments

(a)	Non-income producing investment.
(b)	The rate shown is the seven-day current annualized yield at February 28, 2025.
(c)	As defined in the Investment Company Act of 1940, as amended, an affiliated company is one in which the Fund owns 5% or more of the company’s outstanding voting securities, or a company which is under common ownership or control with the Fund. The value of the holdings and transactions in these affiliated companies during the year ended February 28, 2025 are as follows:

Affiliated issuers	Beginning of period($)	Purchases($)	Sales($)	Net change in unrealized appreciation (depreciation)($)	End of period($)	Realized gain (loss)($)	Dividends($)	End of period shares
Columbia Short-Term Cash Fund, 4.479%
	23,895,328	398,477,923	(392,791,316 )	133	29,582,068	(1,962 )	1,558,060	29,585,027

Currency Legend

USD

US Dollar

Fair value measurements

The Fund categorizes its fair value measurements according to a three-level hierarchy that maximizes the use of observable inputs and minimizes the use of unobservable inputs by prioritizing that the most observable input be used when available. Observable inputs are those that market participants would use in pricing an investment based on market data obtained from sources independent of the reporting entity. Unobservable inputs are those that reflect the Fund’s assumptions about the information market participants would use in pricing an investment. An investment’s level within the fair value hierarchy is based on the lowest level of any input that is deemed significant to the asset’s or liability’s fair value measurement. The input levels are not necessarily an indication of the risk or liquidity associated with investments at that level. For example, certain U.S. government securities are generally high quality and liquid, however, they are reflected as Level 2 because the inputs used to determine fair value may not always be quoted prices in an active market.

Fair value inputs are summarized in the three broad levels listed below:

■

Level 1 — Valuations based on quoted prices for investments in active markets that the Fund has the ability to access at the measurement date. Valuation adjustments are not applied to Level 1 investments.

■

Level 2 — Valuations based on other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risks, etc.).

■

Level 3 — Valuations based on significant unobservable inputs (including the Fund’s own assumptions and judgment in determining the fair value of investments).

Inputs that are used in determining fair value of an investment may include price information, credit data, volatility statistics, and other factors. These inputs can be either observable or unobservable. The availability of observable inputs can vary between investments, and is affected by various factors such as the type of investment, and the volume and level of activity for that investment or similar investments in the marketplace. The inputs will be considered by the Investment Manager, along with any other relevant factors in the calculation of an investment’s fair value. The Fund uses prices and inputs that are current as of the measurement date, which may include periods of market dislocations. During these periods, the availability of prices and inputs may be reduced for many investments. This condition could cause an investment to be reclassified between the various levels within the hierarchy.

Investments falling into the Level 3 category, if any, are primarily supported by quoted prices from brokers and dealers participating in the market for those investments. However, these may be classified as Level 3 investments due to lack of market transparency and corroboration to support these quoted prices. Additionally, valuation models may be used as the pricing source for any remaining investments classified as Level 3. These models may rely on one or more significant unobservable inputs and/or significant assumptions by the Investment Manager. Inputs used in valuations may include, but are not limited to, financial statement analysis, capital account balances, discount rates and estimated cash flows, and comparable company data.

The Fund’s Board of Trustees (the Board) has designated the Investment Manager, through its Valuation Committee (the Committee), as valuation designee, responsible for determining the fair value of the assets of the Fund for which market quotations are not readily available using valuation procedures approved by the Board. The Committee consists of voting and non-voting members from various groups within the Investment Manager’s organization, including operations and accounting, trading and investments, compliance, risk management and legal.

The Committee meets at least monthly to review and approve valuation matters, which may include a description of specific valuation determinations, data regarding pricing information received from approved pricing vendors and brokers and the results of Board-approved valuation policies and procedures (the Policies). The Policies address, among other things, instances when market quotations are or are not readily available, including recommendations of third party pricing vendors and a determination of appropriate pricing methodologies; events that require specific valuation determinations and assessment of fair value techniques; securities with a potential for stale pricing, including those that are illiquid, restricted, or in default; and the effectiveness of third party pricing vendors, including periodic reviews of vendors. The Committee meets more frequently, as needed, to discuss additional valuation matters, which may include the need to review back-testing results, review time-sensitive information or approve related valuation actions. Representatives of Columbia Management Investment Advisers, LLC report to the Board at each of its regularly scheduled meetings to discuss valuation matters and actions during the period, similar to those described earlier.

The following table is a summary of the inputs used to value the Fund’s investments at February 28, 2025:

	Level 1 ($)	Level 2 ($)	Level 3 ($)	Total ($)
Investments in Securities
Common Stocks
Communication Services	35,766,656	—	—	35,766,656
Consumer Discretionary	337,016,682	—	—	337,016,682
Consumer Staples	117,872,144	—	—	117,872,144

The accompanying Notes to Financial Statements are an integral part of this statement.

Columbia Mid Cap Index Fund | 2025

Statement of Assets and Liabilities

February 28, 2025

Assets
Investments in securities, at value
Unaffiliated issuers (cost $1,542,204,683)	$2,461,282,958
Affiliated issuers (cost $29,579,576)	29,582,068
Margin deposits on:
Futures contracts	3,323,775
Receivable for:
Capital shares sold	13,570,081
Dividends	1,591,419
Foreign tax reclaims	8,360
Variation margin for futures contracts	344,300
Expense reimbursement due from Investment Manager	6,491
Prepaid expenses	12,120
Total assets	2,509,721,572
Liabilities
Payable for:
Capital shares redeemed	2,132,420
Variation margin for futures contracts	172
Management services fees	13,537
Distribution and/or service fees	3,785
Transfer agent fees	216,037
Compensation of chief compliance officer	481
Compensation of board members	4,416
Other expenses	54,690
Deferred compensation of board members	341,391
Total liabilities	2,766,929
Net assets applicable to outstanding capital stock	$2,506,954,643
Represented by
Paid in capital	1,527,282,595
Total distributable earnings (loss)	979,672,048
Total - representing net assets applicable to outstanding capital stock	$2,506,954,643
Class A
Net assets	$557,409,301
Shares outstanding	38,398,683
Net asset value per share	$14.52
Institutional Class
Net assets	$1,077,208,739
Shares outstanding	74,829,562
Net asset value per share	$14.40
Institutional 2 Class
Net assets	$546,625,014
Shares outstanding	36,479,726
Net asset value per share	$14.98
Institutional 3 Class
Net assets	$325,711,589
Shares outstanding	23,429,415
Net asset value per share	$13.90

The accompanying Notes to Financial Statements are an integral part of this statement.

Columbia Mid Cap Index Fund | 2025

Statement of Operations

Year Ended February 28, 2025

Net investment income
Income:
Dividends — unaffiliated issuers	$37,566,695
Dividends — affiliated issuers	1,558,060
Foreign taxes withheld	(30,802 )
Total income	39,093,953
Expenses:
Management services fees	5,248,744
Distribution and/or service fees
Class A	1,520,736
Transfer agent fees
Class A	677,139
Institutional Class	1,208,517
Institutional 2 Class	349,928
Institutional 3 Class	21,540
Custodian fees	35,228
Printing and postage fees	62,754
Registration fees	81,178
Licensing fees and expenses	28,838
Accounting services fees	31,523
Legal fees	43,239
Interest on collateral	124
Interest on interfund lending	3,396
Compensation of chief compliance officer	480
Compensation of board members	38,515
Deferred compensation of board members	66,999
Other	47,229
Total expenses	9,466,107
Fees waived or expenses reimbursed by Investment Manager and its affiliates	(2,677,389 )
Expense reduction	(100 )
Total net expenses	6,788,618
Net investment income	32,305,335
Realized and unrealized gain (loss) — net
Net realized gain (loss) on:
Investments — unaffiliated issuers	249,847,492
Investments — affiliated issuers	(1,962 )
Futures contracts	2,404,467
Net realized gain	252,249,997
Net change in unrealized appreciation (depreciation) on:
Investments — unaffiliated issuers	(65,778,446 )
Investments — affiliated issuers	133
Futures contracts	(2,515,599 )
Net change in unrealized appreciation (depreciation)	(68,293,912 )
Net realized and unrealized gain	183,956,085
Net increase in net assets resulting from operations	$216,261,420

The accompanying Notes to Financial Statements are an integral part of this statement.

Columbia Mid Cap Index Fund | 2025

Statement of Changes in Net Assets

	Year Ended February 28, 2025	Year Ended February 29, 2024
Operations
Net investment income	$32,305,335	$34,383,193
Net realized gain	252,249,997	178,136,400
Net change in unrealized appreciation (depreciation)	(68,293,912 )	93,704,323
Net increase in net assets resulting from operations	216,261,420	306,223,916
Distributions to shareholders
Net investment income and net realized gains
Class A	(61,646,633 )	(46,036,476 )
Institutional Class	(115,547,104 )	(81,262,696 )
Institutional 2 Class	(58,083,384 )	(42,225,235 )
Institutional 3 Class	(38,538,821 )	(29,083,839 )
Total distributions to shareholders	(273,815,942 )	(198,608,246 )
Decrease in net assets from capital stock activity	(63,477,585 )	(62,788,024 )
Total increase (decrease) in net assets	(121,032,107 )	44,827,646
Net assets at beginning of year	2,627,986,750	2,583,159,104
Net assets at end of year	$2,506,954,643	$2,627,986,750

	Year Ended		Year Ended
	February 28, 2025		February 29, 2024
	Shares	Dollars ($)	Shares	Dollars ($)
Capital stock activity
Class A
Shares sold	7,105,564	108,093,751	8,538,158	117,657,199
Distributions reinvested	2,872,907	43,806,872	2,486,549	33,592,879
Shares redeemed	(13,151,207 )	(200,825,884 )	(15,191,510 )	(210,027,705 )
Net decrease	(3,172,736 )	(48,925,261 )	(4,166,803 )	(58,777,627 )
Institutional Class
Shares sold	10,490,250	157,384,602	11,458,915	155,274,018
Distributions reinvested	7,326,362	110,897,091	5,695,333	76,314,719
Shares redeemed	(14,456,623 )	(218,995,008 )	(17,421,616 )	(241,283,166 )
Net increase (decrease)	3,359,989	49,286,685	(267,368 )	(9,694,429 )
Institutional 2 Class
Shares sold	9,709,297	152,194,432	10,379,084	147,340,372
Distributions reinvested	2,583,759	40,584,589	2,249,373	31,237,281
Shares redeemed	(13,910,525 )	(218,338,340 )	(12,764,326 )	(181,795,209 )
Net decrease	(1,617,469 )	(25,559,319 )	(135,869 )	(3,217,556 )
Institutional 3 Class
Shares sold	3,508,049	51,272,997	3,852,383	51,320,957
Distributions reinvested	694,761	10,119,134	615,447	7,992,587
Shares redeemed	(6,912,872 )	(99,671,821 )	(3,780,455 )	(50,411,956 )
Net increase (decrease)	(2,710,062 )	(38,279,690 )	687,375	8,901,588
Total net decrease	(4,140,278 )	(63,477,585 )	(3,882,665 )	(62,788,024 )

The accompanying Notes to Financial Statements are an integral part of this statement.

Columbia Mid Cap Index Fund | 2025

Financial Highlights

The following table is intended to help you understand the Fund’s financial performance. Certain information reflects financial results for a single share of a class held for the periods shown. Per share net investment income (loss) amounts are calculated based on average shares outstanding during the period. Total return assumes reinvestment of all dividends and distributions, if any. Total return does not reflect payment of sales charges, if any. Total return and portfolio turnover are not annualized for periods of less than one year. The ratios of expenses and net investment income are annualized for periods of less than one year. The portfolio turnover rate is calculated without regard to purchase and sales transactions of short-term instruments and certain derivatives, if any. If such transactions were included, the Fund’s portfolio turnover rate may be higher.

	Net asset value, beginning of period	Net investment income	Net realized and unrealized gain (loss)	Total from investment operations	Distributions from net investment income	Distributions from net realized gains	Total distributions to shareholders
Class A
Year Ended 2/28/2025	$14.86	0.16	1.11	1.27	(0.18 )	(1.43 )	(1.61 )
Year Ended 2/29/2024	$14.29	0.17	1.49	1.66	(0.16 )	(0.93 )	(1.09 )
Year Ended 2/28/2023	$16.13	0.16	(0.50 )	(0.34 )	(0.16 )	(1.34 )	(1.50 )
Year Ended 2/28/2022	$17.72	0.14 (f)	1.30	1.44	(0.13 )	(2.90 )	(3.03 )
Year Ended 2/28/2021	$14.07	0.14	5.02	5.16	(0.16 )	(1.35 )	(1.51 )
Institutional Class
Year Ended 2/28/2025	$14.75	0.19	1.11	1.30	(0.22 )	(1.43 )	(1.65 )
Year Ended 2/29/2024	$14.19	0.20	1.49	1.69	(0.20 )	(0.93 )	(1.13 )
Year Ended 2/28/2023	$16.03	0.19	(0.49 )	(0.30 )	(0.20 )	(1.34 )	(1.54 )
Year Ended 2/28/2022	$17.63	0.19 (f)	1.29	1.48	(0.18 )	(2.90 )	(3.08 )
Year Ended 2/28/2021	$14.00	0.18	4.99	5.17	(0.19 )	(1.35 )	(1.54 )
Institutional 2 Class
Year Ended 2/28/2025	$15.29	0.20	1.14	1.34	(0.22 )	(1.43 )	(1.65 )
Year Ended 2/29/2024	$14.67	0.21	1.54	1.75	(0.20 )	(0.93 )	(1.13 )
Year Ended 2/28/2023	$16.52	0.20	(0.51 )	(0.31 )	(0.20 )	(1.34 )	(1.54 )
Year Ended 2/28/2022	$18.08	0.19 (f)	1.33	1.52	(0.18 )	(2.90 )	(3.08 )
Year Ended 2/28/2021	$14.32	0.18	5.12	5.30	(0.19 )	(1.35 )	(1.54 )
Institutional 3 Class
Year Ended 2/28/2025	$14.29	0.19	1.07	1.26	(0.22 )	(1.43 )	(1.65 )
Year Ended 2/29/2024	$13.79	0.19	1.44	1.63	(0.20 )	(0.93 )	(1.13 )
Year Ended 2/28/2023	$15.63	0.18	(0.48 )	(0.30 )	(0.20 )	(1.34 )	(1.54 )
Year Ended 2/28/2022	$17.25	0.18 (f)	1.28	1.46	(0.18 )	(2.90 )	(3.08 )
Year Ended 2/28/2021	$13.73	0.17	4.89	5.06	(0.19 )	(1.35 )	(1.54 )

Notes to Financial Highlights
(a)	In addition to the fees and expenses that the Fund bears directly, the Fund indirectly bears a pro rata share of the fees and expenses of any other funds in which it invests. Such indirect expenses are not included in the Fund’s reported expense ratios.
(b)	Total net expenses include the impact of certain fee waivers/expense reimbursements made by the Investment Manager and certain of its affiliates, if applicable.
(c)	Ratios include interest on collateral expense which is less than 0.01%.
(d)	Ratios include interfund lending expense which is less than 0.01%.
(e)	The benefits derived from expense reductions had an impact of less than 0.01%.
(f)	Net investment income per share includes special dividends. The per share effect of these dividends amounted to:

Year Ended	Class A	Institutional Class	Institutional 2 Class	Institutional 3 Class
02/28/2022	$0.01	$0.01	$0.01	$0.01

The accompanying Notes to Financial Statements are an integral part of this statement.

Columbia Mid Cap Index Fund | 2025

Financial Highlights (continued)

	Net asset value, end of period	Total return	Total gross expense ratio to average net assets(a)	Total net expense ratio to average net assets(a),(b)	Net investment income ratio to average net assets	Portfolio turnover	Net assets, end of period (000’s)
Class A
Year Ended 2/28/2025	$14.52	8.23%	0.58% (c),(d)	0.45% (c),(d),(e)	1.04%	16%	$557,409
Year Ended 2/29/2024	$14.86	12.58%	0.59% (c)	0.45% (c),(e)	1.19%	19%	$617,822
Year Ended 2/28/2023	$14.29	(1.05% )	0.58% (c),(d)	0.45% (c),(d),(e)	1.10%	12%	$653,592
Year Ended 2/28/2022	$16.13	7.48%	0.58% (c),(d)	0.45% (c),(d),(e)	0.78%	16%	$768,487
Year Ended 2/28/2021	$17.72	39.13%	0.58% (d)	0.45% (d),(e)	1.01%	14%	$902,341
Institutional Class
Year Ended 2/28/2025	$14.40	8.48%	0.33% (c),(d)	0.20% (c),(d),(e)	1.28%	16%	$1,077,209
Year Ended 2/29/2024	$14.75	12.88%	0.34% (c)	0.20% (c),(e)	1.45%	19%	$1,054,017
Year Ended 2/28/2023	$14.19	(0.80% )	0.33% (c),(d)	0.20% (c),(d),(e)	1.35%	12%	$1,017,847
Year Ended 2/28/2022	$16.03	7.72%	0.33% (c),(d)	0.20% (c),(d),(e)	1.03%	16%	$1,534,550
Year Ended 2/28/2021	$17.63	39.49%	0.34% (d)	0.20% (d),(e)	1.25%	14%	$1,642,259
Institutional 2 Class
Year Ended 2/28/2025	$14.98	8.44%	0.28% (c),(d)	0.20% (c),(d)	1.29%	16%	$546,625
Year Ended 2/29/2024	$15.29	12.86%	0.28% (c)	0.20% (c)	1.44%	19%	$582,545
Year Ended 2/28/2023	$14.67	(0.84% )	0.28% (c),(d)	0.20% (c),(d)	1.35%	12%	$560,860
Year Ended 2/28/2022	$16.52	7.75%	0.27% (c),(d)	0.20% (c),(d)	1.03%	16%	$634,732
Year Ended 2/28/2021	$18.08	39.52%	0.28% (d)	0.20% (d)	1.24%	14%	$843,249
Institutional 3 Class
Year Ended 2/28/2025	$13.90	8.47%	0.22% (c),(d)	0.20% (c),(d)	1.29%	16%	$325,712
Year Ended 2/29/2024	$14.29	12.81%	0.22% (c)	0.20% (c)	1.44%	19%	$373,603
Year Ended 2/28/2023	$13.79	(0.82% )	0.23% (c),(d)	0.20% (c),(d)	1.36%	12%	$350,859
Year Ended 2/28/2022	$15.63	7.78%	0.22% (c),(d)	0.20% (c),(d)	1.04%	16%	$69,950
Year Ended 2/28/2021	$17.25	39.46%	0.23% (d)	0.20% (d)	1.23%	14%	$64,740

The accompanying Notes to Financial Statements are an integral part of this statement.

Columbia Mid Cap Index Fund | 2025

Notes to Financial Statements

February 28, 2025

Note 1. Organization

Columbia Mid Cap Index Fund (the Fund), a series of Columbia Funds Series Trust (the Trust), is a diversified fund. The Trust is registered under the Investment Company Act of 1940, as amended (the 1940 Act), as an open-end management investment company organized as a Delaware statutory trust.

Fund shares

The Trust may issue an unlimited number of shares (without par value). The Fund offers each of the share classes listed in the Statement of Assets and Liabilities. Although all share classes generally have identical voting, dividend and liquidation rights, each share class votes separately when required by the Trust’s organizational documents or by law. Each share class has its own expense and sales charge structure. Different share classes may have different minimum initial investment amounts and pay different net investment income distribution amounts to the extent the expenses of distributing such share classes vary. Distributions to shareholders in a liquidation will be proportional to the net asset value of each share class.

As described in the Fund’s prospectus, Class A shares are offered to the general public for investment. Institutional Class, Institutional 2 Class and Institutional 3 Class shares are available for purchase through authorized investment professionals to omnibus retirement plans or to institutional investors and to certain other investors as also described in the Fund’s prospectus.

Note 2. Summary of significant accounting policies

Basis of preparation

The Fund is an investment company that applies the accounting and reporting guidance in the Financial Accounting Standards Board (FASB) Accounting Standards Codification Topic 946, Financial Services - Investment Companies (ASC 946). The financial statements are prepared in accordance with U.S. generally accepted accounting principles (GAAP), which requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of income and expenses during the reporting period. Actual results could differ from those estimates.

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

Segment reporting

In this reporting period, the Fund 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 its results of operations. The intent of the ASU 2023-07 is to enable investors to better understand an entity’s overall performance and to assess its potential future cash flows through improved segment disclosures.

The chief operating decision maker (CODM) for the Fund is Columbia Management Investment Advisers, LLC through its Investment Oversight Committee and Global Executive Group, which are responsible for assessing performance and making decisions about resource allocation. The CODM has determined that the Fund has a single operating segment because the CODM monitors the operating results of the 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 provided to and reviewed by the CODM is consistent with that presented within the Fund’s financial statements.

Security valuation

Equity securities listed on an exchange are valued at the closing price or last trade price on their primary exchange at the close of business of the New York Stock Exchange. Securities with a closing price not readily available or not listed on any exchange are valued at the mean between the closing bid and ask prices. Listed preferred stocks convertible into common stocks are valued using an evaluated price from a pricing service.

Columbia Mid Cap Index Fund | 2025

Notes to Financial Statements (continued)

February 28, 2025

Foreign equity securities are valued based on the closing price or last trade price on their primary exchange at the close of business of the New York Stock Exchange. If any foreign equity security closing prices are not readily available, the securities are valued at the mean of the latest quoted bid and ask prices on such exchanges or markets. Foreign currency exchange rates are determined at the scheduled closing time of the New York Stock Exchange. Many securities markets and exchanges outside the U.S. close prior to the close of the New York Stock Exchange; therefore, the closing prices for securities in such markets or on such exchanges may not fully reflect events that occur after such close but before the close of the New York Stock Exchange. In those situations, foreign securities will be fair valued pursuant to a policy approved by the Board of Trustees. Under the policy, the Fund may utilize a third-party pricing service to determine these fair values. The third-party pricing service takes into account multiple factors, including relevant general and sector indices, currency fluctuations, depositary receipts, and futures, as applicable, to determine a good faith estimate that reasonably reflects the current market conditions as of the close of the New York Stock Exchange. The fair value of a security is likely to be different from the quoted or published price, if available.

Investments in open-end investment companies (other than exchange-traded funds (ETFs)), are valued at the latest net asset value reported by those companies as of the valuation time.

Futures and options on futures contracts are valued based upon the settlement price at the close of regular trading on their principal exchanges or, in the absence of a settlement price, at the mean of the latest quoted bid and ask prices.

Investments for which market quotations are not readily available, or that have quotations which management believes are not reflective of market value or reliable, are valued at fair value as determined in good faith under procedures approved by the Board of Trustees. If a security or class of securities (such as foreign securities) is valued at fair value, such value is likely to be different from the quoted or published price for the security, if available.

The determination of fair value often requires significant judgment. To determine fair value, management may use assumptions including but not limited to future cash flows and estimated risk premiums. Multiple inputs from various sources may be used to determine fair value.

GAAP requires disclosure regarding the inputs and valuation techniques used to measure fair value and any changes in valuation inputs or techniques. In addition, investments shall be disclosed by major category. This information is disclosed following the Fund’s Portfolio of Investments.

Derivative instruments

The Fund invests in certain derivative instruments, as detailed below, in seeking to meet its investment objectives. Derivatives are instruments whose values depend on, or are derived from, in whole or in part, the value of one or more securities, currencies, commodities, indices, or other assets or instruments. Derivatives may be used to increase investment flexibility (including to maintain cash reserves while maintaining desired exposure to certain assets), for risk management (hedging) purposes, to facilitate trading, to reduce transaction costs and to pursue higher investment returns. The Fund may also use derivative instruments to mitigate certain investment risks, such as foreign currency exchange rate risk, interest rate risk and credit risk. Derivatives may involve various risks, including the potential inability of the counterparty to fulfill its obligations under the terms of the contract, the potential for an illiquid secondary market (making it difficult for the Fund to sell or terminate, including at favorable prices) and the potential for market movements which may expose the Fund to gains or losses in excess of the amount shown in the Statement of Assets and Liabilities. The notional exposure of a financial instrument is the nominal or face amount that is used to calculate payments made on that instrument and/or changes in value for the instrument. The notional exposure is a hypothetical underlying quantity upon which payment obligations are computed. Notional exposures provide a gauge for how the Fund may behave given changes in the underlying rate, asset or reference instrument and individual markets. The notional amounts of derivative instruments, if applicable, are not recorded in the financial statements.

A derivative instrument may suffer a marked-to-market loss if the value of the contract decreases due to an unfavorable change in the market rates or values of the underlying instrument. Losses can also occur if the counterparty does not perform its obligations under the contract. The Fund’s risk of loss from counterparty credit risk on over-the-counter derivatives is generally expected to be limited to the aggregate unrealized gain netted against any collateral held by the Fund and the

Columbia Mid Cap Index Fund | 2025

Notes to Financial Statements (continued)

February 28, 2025

amount of any variation margin held by the counterparty, plus any replacement costs or related amounts. With exchange-traded or centrally cleared derivatives, there is reduced counterparty credit risk to the Fund since the clearinghouse or central counterparty provides some protection in the case of clearing member default. The clearinghouse or central counterparty stands between the buyer and the seller of the contract; therefore, failure of the clearinghouse or central counterparty may pose additional counterparty credit risk. However, credit risk still exists in exchange-traded or centrally cleared derivatives with respect to initial and variation margin that is held in a broker’s customer account. While clearing brokers are required to segregate customer margin from their own assets, in the event that a clearing broker becomes insolvent or goes into bankruptcy and at that time there is a shortfall in the aggregate amount of margin held by the clearing broker for all its clients and such shortfall is remedied by the central counterparty or otherwise, U.S. bankruptcy laws will typically allocate that shortfall on a pro-rata basis across all the clearing broker’s customers (including the Fund), potentially resulting in losses to the Fund.

In order to better define its contractual rights and to secure rights that will help the Fund mitigate its counterparty risk in respect of over-the-counter derivatives, the Fund may enter into an International Swaps and Derivatives Association, Inc. Master Agreement (ISDA Master Agreement) or similar agreement with its derivatives counterparties. An ISDA Master Agreement is an agreement between the Fund and a counterparty that governs over-the-counter derivatives and foreign exchange forward contracts and contains, among other things, collateral posting terms and netting provisions in the event of a default and/or termination event. Under an ISDA Master Agreement, the Fund may, under certain circumstances, offset with the counterparty certain derivative instruments’ payables and/or receivables with collateral held and/or posted and create one single net payment. The provisions of the ISDA Master Agreement typically permit a single net payment in the event of default (close-out netting), including the bankruptcy or insolvency of the counterparty. Note, however, that bankruptcy or insolvency laws of a particular jurisdiction may impose restrictions on or prohibitions against the right of offset or netting in bankruptcy, insolvency or other events.

Collateral (margin) requirements differ by type of derivative. Margin requirements are established by the clearinghouse or central counterparty for exchange-traded and centrally cleared derivatives. Brokers can ask for margin in excess of the minimum in certain circumstances. Collateral terms for most over-the-counter derivatives are subject to regulatory requirements to exchange variation margin with trading counterparties and may have contract specific margin terms as well. For over-the-counter derivatives traded under an ISDA Master Agreement, the collateral requirements are typically calculated by netting the marked-to-market amount for each transaction under such agreement and comparing that amount to the value of any variation margin currently pledged by the Fund and/or the counterparty. Generally, the amount of collateral due from or to a party has to exceed a minimum transfer amount threshold (e.g., $250,000) before a transfer has to be made. To the extent amounts due to the Fund from its counterparties are not fully collateralized, contractually or otherwise, the Fund bears the risk of loss from counterparty nonperformance. The Fund may also pay interest expense on cash collateral received from the broker or receive interest income on cash collateral pledged to the broker. The Fund attempts to mitigate counterparty risk by only entering into agreements with counterparties that it believes have the financial resources to honor their obligations and by monitoring the financial stability of those counterparties.

Certain ISDA Master Agreements allow counterparties of over-the-counter derivatives transactions to terminate derivatives contracts prior to maturity in the event the Fund’s net asset value declines by a stated percentage over a specified time period or if the Fund fails to meet certain terms of the ISDA Master Agreement, which would cause the Fund to accelerate payment of any net liability owed to the counterparty. The Fund also has termination rights if the counterparty fails to meet certain terms of the ISDA Master Agreement. In determining whether to exercise such termination rights, the Fund would consider, in addition to counterparty credit risk, whether termination would result in a net liability owed from the counterparty.

For financial reporting purposes, the Fund does not offset derivative assets and derivative liabilities that are subject to netting arrangements in the Statement of Assets and Liabilities.

Futures contracts

Futures contracts are exchange-traded and represent commitments for the future purchase or sale of an asset at a specified price on a specified date. The Fund bought and sold futures contracts to maintain appropriate equity market exposure while keeping sufficient cash to accommodate daily redemptions. These instruments may be used for other purposes in future

Columbia Mid Cap Index Fund | 2025

Notes to Financial Statements (continued)

February 28, 2025

periods. Upon entering into futures contracts, the Fund bears risks that it may not achieve the anticipated benefits of the futures contracts and may realize a loss. Additional risks include counterparty credit risk, the possibility of an illiquid market, and that a change in the value of the contract or option may not correlate with changes in the value of the underlying asset.

Upon entering into a futures contract, the Fund deposits cash or securities with the broker, known as a futures commission merchant (FCM), in an amount sufficient to meet the initial margin requirement. The initial margin deposit must be maintained at an established level over the life of the contract. Cash deposited as initial margin is recorded in the Statement of Assets and Liabilities as margin deposits. Securities deposited as initial margin are designated in the Portfolio of Investments. Subsequent payments (variation margin) are made or received by the Fund each day. The variation margin payments are equal to the daily change in the contract value and are recorded as variation margin receivable or payable and are offset in unrealized gains or losses. The Fund generally expects to earn interest income on its margin deposits. The Fund recognizes a realized gain or loss when the contract is closed or expires. Futures contracts involve, to varying degrees, risk of loss in excess of the variation margin disclosed in the Statement of Assets and Liabilities.

Effects of derivative transactions in the financial statements

The following tables are intended to provide additional information about the effect of derivatives on the financial statements of the Fund, including: the fair value of derivatives by risk category and the location of those fair values in the Statement of Assets and Liabilities; and the impact of derivative transactions over the period in the Statement of Operations, including realized and unrealized gains (losses). The derivative instrument schedules following the Portfolio of Investments present additional information regarding derivative instruments outstanding at the end of the period, if any.

The following table is a summary of the fair value of derivative instruments (not considered to be hedging instruments for accounting disclosure purposes) at February 28, 2025:

	Liability derivatives
Risk exposure category	Statement of assets and liabilities location	Fair value ($)
Equity risk	Component of total distributable earnings (loss) — unrealized depreciation on futures contracts	1,282,272 *

*	Includes cumulative appreciation (depreciation) as reported in the tables following the Portfolio of Investments. Only the current day’s variation margin for futures and centrally cleared swaps, if any, is reported in receivables or payables in the Statement of Assets and Liabilities.

The following table indicates the effect of derivative instruments (not considered to be hedging instruments for accounting disclosure purposes) in the Statement of Operations for the year ended February 28, 2025:

Amount of realized gain (loss) on derivatives recognized in income
Risk exposure category	Futures contracts ($)
Equity risk	2,404,467

Change in unrealized appreciation (depreciation) on derivatives recognized in income
Risk exposure category	Futures contracts ($)
Equity risk	(2,515,599 )

The following table is a summary of the average daily outstanding volume by derivative instrument for the year ended February 28, 2025:

Derivative instrument	Average notional amounts ($)
Futures contracts — long	36,475,477

Columbia Mid Cap Index Fund | 2025

Notes to Financial Statements (continued)

February 28, 2025

Security transactions

Security transactions are accounted for on the trade date. Cost is determined and gains (losses) are based upon the specific identification method for both financial statement and federal income tax purposes.

Income recognition

Corporate actions and dividend income are generally recorded net of any non-reclaimable tax withholdings, on the ex-dividend date or upon receipt of an ex-dividend notification in the case of certain foreign securities.

The Fund may receive distributions from holdings in equity securities, business development companies (BDCs), exchange-traded funds (ETFs), limited partnerships (LPs), other regulated investment companies (RICs), and real estate investment trusts (REITs), which report information as to the tax character of their distributions annually. These distributions are allocated to dividend income, capital gain and return of capital based on actual information reported. Return of capital is recorded as a reduction of the cost basis of securities held. If the Fund no longer owns the applicable securities, return of capital is recorded as a realized gain. With respect to REITs, to the extent actual information has not yet been reported, estimates for return of capital are made by Columbia Management Investment Advisers, LLC (the Investment Manager), a wholly-owned subsidiary of Ameriprise Financial, Inc. (Ameriprise Financial). The Investment Manager’s estimates are subsequently adjusted when the actual character of the distributions is disclosed by the REITs, which could result in a proportionate change in return of capital to shareholders.

Awards from class action litigation are recorded as a reduction of cost basis if the Fund still owns the applicable securities on the payment date. If the Fund no longer owns the applicable securities on the payment date, the proceeds are recorded as realized gains.

Expenses

General expenses of the Trust are allocated to the Fund and other funds of the Trust based upon relative net assets or other expense allocation methodologies determined by the nature of the expense. Expenses directly attributable to the Fund are charged to the Fund. Expenses directly attributable to a specific class of shares are charged to that share class.

Determination of class net asset value

All income, expenses (other than class-specific expenses, which are charged to that share class, as shown in the Statement of Operations) and realized and unrealized gains (losses) are allocated to each class of the Fund on a daily basis, based on the relative net assets of each class, for purposes of determining the net asset value of each class.

Federal income tax status

The Fund intends to qualify each year as a regulated investment company under Subchapter M of the Internal Revenue Code, as amended, and will distribute substantially all of its investment company taxable income and net capital gain, if any, for its tax year, and as such will not be subject to federal income taxes. In addition, the Fund intends to distribute in each calendar year substantially all of its ordinary income, capital gain net income and certain other amounts, if any, such that the Fund should not be subject to federal excise tax. Therefore, no federal income or excise tax provision is recorded.

Foreign taxes

The Fund may be subject to foreign taxes on income, gains on investments or currency repatriation, a portion of which may be recoverable. The Fund will accrue such taxes and recoveries, as applicable, based upon its current interpretation of tax rules and regulations that exist in the markets in which it invests.

Realized gains in certain countries may be subject to foreign taxes at the Fund level, based on statutory rates. The Fund accrues for such foreign taxes on realized and unrealized gains at the appropriate rate for each jurisdiction, as applicable. The amount, if any, is disclosed as a liability in the Statement of Assets and Liabilities.

Columbia Mid Cap Index Fund | 2025

Notes to Financial Statements (continued)

February 28, 2025

Distributions to shareholders

Distributions from net investment income, if any, are declared and paid semi-annually. Net realized capital gains, if any, are distributed at least annually. Income distributions and capital gain distributions are determined in accordance with federal income tax regulations, which may differ from GAAP.

Guarantees and indemnifications

Under the Trust’s organizational documents and, in some cases, by contract, its officers and trustees are indemnified against certain liabilities arising out of the performance of their duties to the Trust or its funds. In addition, certain of the Fund’s contracts with its service providers contain general indemnification clauses. The Fund’s maximum exposure under these arrangements is unknown since the amount of any future claims that may be made against the Fund cannot be determined, and the Fund has no historical basis for predicting the likelihood of any such claims.

Recent accounting pronouncements and regulatory updates

Accounting Standards Update 2023-09 Income Taxes (Topic 740)

In December 2023, the FASB issued Accounting Standards Update No. 2023-09 Income Taxes (Topic 740) Improvements to Income Tax Disclosures. The amendments were issued to enhance the transparency and decision usefulness of income tax disclosures primarily related to rate reconciliation and income taxes paid information. The amendments are effective for annual periods beginning after December 15, 2024, with early adoption permitted. Management expects that the adoption of the amendments will not have a material impact on its financial statements.

Note 3. Fees and other transactions with affiliates

Management services fees

The Fund has entered into a Management Agreement with Columbia Management Investment Advisers, LLC (the Investment Manager), a wholly-owned subsidiary of Ameriprise Financial, Inc. (Ameriprise Financial). Under the Management Agreement, the Investment Manager provides the Fund with investment research and advice, as well as administrative and accounting services. The management services fee is an annual fee that is equal to 0.20% of the Fund’s daily net assets.

Compensation of Board members

Members of the Board of Trustees who are not officers or employees of the Investment Manager or Ameriprise Financial are compensated for their services to the Fund as disclosed in the Statement of Operations. Under a Deferred Compensation Plan (the Deferred Plan), these members of the Board of Trustees may elect to defer payment of up to 100% of their compensation. Deferred amounts are treated as though equivalent dollar amounts had been invested in shares of certain funds managed by the Investment Manager. The Fund’s liability for these amounts is adjusted for market value changes and remains in the Fund until distributed in accordance with the Deferred Plan. All amounts payable under the Deferred Plan constitute a general unsecured obligation of the Fund. The expense for the Deferred Plan, which includes Trustees’ fees deferred during the current period as well as any gains or losses on the Trustees’ deferred compensation balances as a result of market fluctuations, is included in "Deferred compensation of board members" in the Statement of Operations.

Compensation of Chief Compliance Officer

The Board of Trustees has appointed a Chief Compliance Officer for the Fund in accordance with federal securities regulations. As disclosed in the Statement of Operations, a portion of the Chief Compliance Officer’s total compensation is allocated to the Fund, along with other allocations to affiliated registered investment companies managed by the Investment Manager and its affiliates, based on relative net assets.

Columbia Mid Cap Index Fund | 2025

Notes to Financial Statements (continued)

February 28, 2025

Transfer agency fees

Under a Transfer and Dividend Disbursing Agent Agreement, Columbia Management Investment Services Corp. (the Transfer Agent), an affiliate of the Investment Manager and a wholly-owned subsidiary of Ameriprise Financial, is responsible for providing transfer agency services to the Fund. The Transfer Agent has contracted with SS&C GIDS, Inc. (SS&C GIDS) to serve as sub-transfer agent. The Transfer Agent pays the fees of SS&C GIDS for services as sub-transfer agent and SS&C GIDS is not entitled to reimbursement for such fees from the Fund (with the exception of out-of-pocket fees).

The Fund pays the Transfer Agent a monthly transfer agency fee based on the number or the average value of accounts, depending on the type of account. In addition, the Fund pays the Transfer Agent a fee for shareholder services based on the number of accounts or on a percentage of the average aggregate value of the Fund’s shares maintained in omnibus accounts up to the lesser of the amount charged by the financial intermediary or a cap established by the Board of Trustees from time to time.

The Transfer Agent also receives compensation from the Fund for various shareholder services and reimbursements for certain out-of-pocket fees. Total transfer agency fees for Institutional 2 Class and Institutional 3 Class shares are subject to an annual limitation of not more than 0.07% and 0.02%, respectively, of the average daily net assets attributable to each share class.

For the year ended February 28, 2025, the Fund’s effective transfer agency fee rates as a percentage of average daily net assets of each class were as follows:

	Effective rate (%)
Class A	0.11
Institutional Class	0.11
Institutional 2 Class	0.06
Institutional 3 Class	0.01

An annual minimum account balance fee of $20 may apply to certain accounts with a value below the applicable share class’s initial minimum investment requirements to reduce the impact of small accounts on transfer agency fees. These minimum account balance fees are remitted to the Fund and recorded as part of expense reductions in the Statement of Operations. For the year ended February 28, 2025, these minimum account balance fees reduced total expenses of the Fund by $100.

Distribution and service fees

The Fund has entered into an agreement with Columbia Management Investment Distributors, Inc. (the Distributor), an affiliate of the Investment Manager and a wholly-owned subsidiary of Ameriprise Financial, for distribution and shareholder services. The Board of Trustees has approved, and the Fund has adopted, distribution and shareholder service plans (the Plans) applicable to certain share classes, which set the distribution and service fees for the Fund. These fees are calculated daily and are intended to compensate the Distributor and/or eligible selling and/or servicing agents for selling shares of the Fund and providing services to investors.

Under the Plans, the Fund pays a monthly combined distribution and service fee to the Distributor at the maximum annual rate of 0.25% of the average daily net assets attributable to Class A shares of the Fund.

Sales charges (unaudited)

Contingent deferred sales charges (CDSCs) received by the Distributor for distributing Fund shares for the year ended February 28, 2025, if any, are listed below. These CDSCs are from the sale of shares issued by the Fund in exchange for shares of a fund subject to a CDSC that were subsequently redeemed within the CDSC timeframe imposed from the original purchase.

	Front End (%)	CDSC (%)	Amount ($)
Class A	—	—	1,515

The Fund’s other share classes are not subject to sales charges.

Columbia Mid Cap Index Fund | 2025

Notes to Financial Statements (continued)

February 28, 2025

Expenses waived/reimbursed by the Investment Manager and its affiliates

The Investment Manager and certain of its affiliates have contractually agreed to waive fees and/or reimburse expenses (excluding certain fees and expenses described below) for the period(s) disclosed below, unless sooner terminated at the sole discretion of the Board of Trustees, so that the Fund’s net operating expenses, after giving effect to fees waived/expenses reimbursed and any balance credits and/or overdraft charges from the Fund’s custodian, do not exceed the following annual rate(s) as a percentage of the classes’ average daily net assets:

	Fee rate(s) contractual through June 30, 2025 (%)
Class A	0.45
Institutional Class	0.20
Institutional 2 Class	0.20
Institutional 3 Class	0.20

Under the agreement governing these fee waivers and/or expense reimbursement arrangements, the following fees and expenses are excluded from the waiver/reimbursement commitment, and therefore will be paid by the Fund, if applicable: taxes (including foreign transaction taxes), expenses associated with investments in affiliated and non-affiliated pooled investment vehicles (including mutual funds and exchange-traded funds), transaction costs and brokerage commissions, costs related to any securities lending program, dividend expenses associated with securities sold short, inverse floater program fees and expenses, transaction charges and interest on borrowed money, interest, costs associated with shareholder meetings, infrequent and/or unusual expenses and any other expenses the exclusion of which is specifically approved by the Board of Trustees. This agreement may be modified or amended only with approval from the Investment Manager, certain of its affiliates and the Fund. Any fees waived and/or expenses reimbursed under the expense reimbursement arrangements described above are not recoverable by the Investment Manager or its affiliates in future periods.

Note 4. Federal tax information

The timing and character of income and capital gain distributions are determined in accordance with income tax regulations, which may differ from GAAP because of temporary or permanent book to tax differences.

At February 28, 2025, these differences were primarily due to differing treatment for deferral/reversal of wash sale losses, derivative investments, trustees’ deferred compensation and earnings and profits distributed to shareholders on the redemption of shares. To the extent these differences were permanent, reclassifications were made among the components of the Fund’s net assets. Temporary differences do not require reclassifications.

The following reclassifications were made:

Undistributed net investment income ($)	Accumulated net realized gain ($)	Paid in capital ($)
—	(20,887,000 )	20,887,000

Net investment income (loss) and net realized gains (losses), as disclosed in the Statement of Operations, and net assets were not affected by this reclassification.

The tax character of distributions paid during the years indicated was as follows:

Year Ended February 28, 2025			Year Ended February 29, 2024
Ordinary income ($)	Long-term capital gains ($)	Total ($)	Ordinary income ($)	Long-term capital gains ($)	Total ($)
68,039,663	205,776,279	273,815,942	33,349,547	165,258,699	198,608,246

Short-term capital gain distributions, if any, are considered ordinary income distributions for tax purposes.

Columbia Mid Cap Index Fund | 2025

Notes to Financial Statements (continued)

February 28, 2025

At February 28, 2025, the components of distributable earnings on a tax basis were as follows:

Undistributed ordinary income ($)	Undistributed long-term capital gains ($)	Capital loss carryforwards ($)	Net unrealized appreciation ($)
17,473,600	49,507,110	—	913,032,729

At February 28, 2025, the cost of all investments for federal income tax purposes along with the aggregate gross unrealized appreciation and depreciation based on that cost was:

Federal tax cost ($)	Gross unrealized appreciation ($)	Gross unrealized (depreciation) ($)	Net unrealized appreciation ($)
1,576,550,025	1,032,634,373	(119,601,644 )	913,032,729

Tax cost of investments and unrealized appreciation/(depreciation) may also include timing differences that do not constitute adjustments to tax basis.

Management of the Fund has concluded that there are no significant uncertain tax positions in the Fund that would require recognition in the financial statements. However, management’s conclusion may be subject to review and adjustment at a later date based on factors including, but not limited to, new tax laws, regulations, and administrative interpretations (including relevant court decisions). Generally, the Fund’s federal tax returns for the prior three fiscal years remain subject to examination by the Internal Revenue Service.

Note 5. Portfolio information

The cost of purchases and proceeds from sales of securities, excluding short-term investments and derivatives, if any, aggregated to $412,514,611 and $742,748,171, respectively, for the year ended February 28, 2025. The amount of purchase and sale activity impacts the portfolio turnover rate reported in the Financial Highlights.

Note 6. Affiliated money market fund

The Fund invests in Columbia Short-Term Cash Fund, an affiliated money market fund established for the exclusive use by the Fund and other affiliated funds (the Affiliated MMF). The income earned by the Fund from such investments is included as Dividends - affiliated issuers in the Statement of Operations. As an investing fund, the Fund indirectly bears its proportionate share of the expenses of the Affiliated MMF. The Affiliated MMF prices its shares with a floating net asset value. The Securities and Exchange Commission has adopted amendments to money market fund rules requiring institutional prime money market funds like the Affiliated MMF to be subject to a discretionary liquidity fee of up to 2% if the imposition of such a fee is determined to be in the best interest of the Affiliated MMF and to a mandatory liquidity fee if daily net redemptions exceed 5% of net assets.

Note 7. Interfund lending

Pursuant to an exemptive order granted by the Securities and Exchange Commission, the Fund participates in a program (the Interfund Program) allowing each participating Columbia Fund (each, a Participating Fund) to lend money directly to and, except for closed-end funds and money market funds, borrow money directly from other Participating Funds for temporary purposes. The amounts eligible for borrowing and lending under the Interfund Program are subject to certain restrictions.

Interfund loans are subject to the risk that the borrowing fund could be unable to repay the loan when due, and a delay in repayment to the lending fund could result in lost opportunities and/or additional lending costs. The exemptive order is subject to conditions intended to mitigate conflicts of interest arising from the Investment Manager’s relationship with each Participating Fund.

The Fund’s activity in the Interfund Program during the year ended February 28, 2025 was as follows:

Borrower or lender	Average loan balance ($)	Weighted average interest rate (%)	Number of days with outstanding loans
Borrower	10,400,000	5.87	2

Columbia Mid Cap Index Fund | 2025

Notes to Financial Statements (continued)

February 28, 2025

Interest expense incurred by the Fund is recorded as Interest on interfund lending in the Statement of Operations. The Fund had no outstanding interfund loans at February 28, 2025.

Note 8. Line of credit

The Fund has access to a revolving credit facility with a syndicate of banks led by JPMorgan Chase Bank, N.A., Citibank, N.A. and Wells Fargo Bank, N.A. whereby the Fund may borrow for the temporary funding of shareholder redemptions or for other temporary or emergency purposes. Pursuant to an October 24, 2024 amendment and restatement, the credit facility, which is an agreement between the Fund and certain other funds managed by the Investment Manager or an affiliated investment manager, severally and not jointly, permits aggregate borrowings up to $900 million. Interest is currently charged to each participating fund based on its borrowings at a rate equal to the higher of (i) the federal funds effective rate, (ii) the secured overnight financing rate plus 0.10% and (iii) the overnight bank funding rate, plus 1.00% in each case. Each borrowing under the credit facility matures no later than 60 days after the date of borrowing. The Fund also pays a commitment fee equal to its pro rata share of the unused amount of the credit facility at a rate of 0.15% per annum. The commitment fee is included in other expenses in the Statement of Operations. This agreement expires annually in October unless extended or renewed. Prior to the October 24, 2024 amendment and restatement, the Fund had access to a revolving credit facility with a syndicate of banks led by JPMorgan Chase Bank, N.A., Citibank, N.A. and Wells Fargo Bank, N.A. which permitted collective borrowings up to $900 million. Interest was charged to each participating fund based on its borrowings at a rate equal to the higher of (i) the federal funds effective rate, (ii) the secured overnight financing rate plus 0.10% and (iii) the overnight bank funding rate, plus 1.00% in each case.

The Fund had no borrowings during the year ended February 28, 2025.

Note 9. Significant risks

Industrials sector risk

The Fund is vulnerable to the particular risks that may affect companies in the industrials sector. Companies in the industrials sector are subject to certain risks, including changes in supply and demand for their specific product or service and for industrial sector products in general, including decline in demand for such products due to rapid technological developments and frequent new product introduction. Performance of such companies may be affected by factors including government regulation, world events, economic conditions and risks for environmental damage and product liability claims.

Market risk

The Fund may incur losses due to declines in the value of one or more securities in which it invests. These declines may be due to factors affecting a particular issuer, or the result of, among other things, political, regulatory, market, economic or social developments affecting the relevant market(s) more generally. In addition, turbulence in financial markets and reduced liquidity in equity, credit and/or fixed income markets may negatively affect many issuers, which could adversely affect the Fund’s ability to price or value hard-to-value assets in thinly traded and closed markets and could cause significant redemptions and operational challenges. Global economies and financial markets are increasingly interconnected, and conditions and events in one country, region or financial market may adversely impact issuers in a different country, region or financial market. These risks may be magnified if certain events or developments adversely interrupt the global supply chain; in these and other circumstances, such risks might affect companies worldwide. As a result, local, regional or global events such as terrorism, war, other conflicts, natural disasters, disease/virus outbreaks and epidemics or other public health issues, recessions, depressions or other events – or the potential for such events – could have a significant negative impact on global economic and market conditions.

Passive investment risk

The Fund is not “actively” managed and may be affected by a general decline in market segments related to its index’s investment exposures. The Fund invests in securities or instruments included in, or believed by the Investment Manager to be representative of the index regardless of their investment merits. The Fund does not seek temporary defensive positions when markets decline or appear overvalued. The decision of whether to remove a security from the tracking index is made by an independent index provider who is not affiliated with the Fund or the Investment Manager.

Columbia Mid Cap Index Fund | 2025

Notes to Financial Statements (continued)

February 28, 2025

Shareholder concentration risk

At February 28, 2025, one unaffiliated shareholder of record owned 24.3% of the outstanding shares of the Fund in one or more accounts. The Fund has no knowledge about whether any portion of those shares was owned beneficially. Affiliated shareholders of record owned 20.3% of the outstanding shares of the Fund in one or more accounts. Fund shares sold to or redeemed by concentrated accounts may have a significant effect on the operations of the Fund. In the case of a large redemption, the Fund may be forced to sell investments at inopportune times, including its liquid positions, which may result in Fund losses and the Fund holding a higher percentage of less liquid positions. Large redemptions could result in decreased economies of scale and increased operating expenses for non-redeeming Fund shareholders.

Small- and mid-cap company risk

Investments in small- and mid-capitalization companies (small- and mid-cap companies) often involve greater risks than investments in larger, more established companies (larger companies) because small- and mid-cap companies tend to have less predictable earnings and may lack the management experience, financial resources, product diversification and competitive strengths of larger companies. Securities of small- and mid-cap companies may be less liquid and more volatile than the securities of larger companies.

Note 10. Subsequent events

Management has evaluated the events and transactions that have occurred through the date the financial statements were issued and noted no items requiring adjustment of the financial statements or additional disclosure.

Note 11. Information regarding pending and settled legal proceedings

Ameriprise Financial and certain of its affiliates are involved, in the normal course of business, in legal proceedings that include regulatory inquiries, arbitration and litigation (including class actions) concerning matters arising in connection with the conduct of their activities as part of a diversified financial services firm. Ameriprise Financial believes that the Fund is not currently the subject of, and that neither Ameriprise Financial nor any of its affiliates are the subject of, any pending legal, arbitration or regulatory proceedings that are likely to have a material adverse effect on the Fund or the ability of Ameriprise Financial or its affiliates to perform under their contracts with the Fund. Ameriprise Financial is required to make quarterly (10-Q), annual (10-K) and, as necessary, 8-K filings with the Securities and Exchange Commission (SEC) on legal and regulatory matters that relate to Ameriprise Financial and its affiliates. Copies of these filings may be obtained by accessing the SEC website at www.sec.gov.

There can be no assurance that these matters, or the adverse publicity associated with them, will not result in increased Fund redemptions, reduced sale of Fund shares or other adverse consequences to the Fund. Further, although we believe proceedings are not likely to have a material adverse effect on the Fund or the ability of Ameriprise Financial or its affiliates to perform under their contracts with the Fund, these proceedings are subject to uncertainties and, as such, it is inherently difficult to determine whether any loss is probable or even reasonably possible, or to reasonably estimate the amount of any loss that may result from such matters. An adverse outcome in one or more of these proceedings could result in adverse judgments, settlements, fines, penalties or other relief, and may lead to further claims, examinations, adverse publicity or reputational damage, each of which could have a material adverse effect on the consolidated financial condition or results of operations or financial condition of Ameriprise Financial or one or more of its affiliates that provide services to the Fund.

Columbia Mid Cap Index Fund | 2025

Report of Independent Registered Public Accounting Firm

To the Board of Trustees of Columbia Funds Series Trust and Shareholders of Columbia Mid Cap Index Fund

Opinion on the Financial Statements

We have audited the accompanying statement of assets and liabilities, including the portfolio of investments, of Columbia Mid Cap Index Fund (one of the funds constituting Columbia Funds Series Trust, referred to hereafter as the "Fund") as of February 28, 2025, the related statement of operations for the year ended February 28, 2025, the statement of changes in net assets for each of the two years in the period ended February 28, 2025, including the related notes, and the financial highlights for each of the five years in the period ended February 28, 2025 (collectively referred to as the "financial statements"). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Fund as of February 28, 2025, the results of its operations for the year then ended, the changes in its net assets for each of the two years in the period ended February 28, 2025 and the financial highlights for each of the five years in the period ended February 28, 2025 in conformity with accounting principles generally accepted in the United States of America.

Basis for Opinion

These financial statements are the responsibility of the Fund’s management. Our responsibility is to express an opinion on the Fund’s financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Fund in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits of these financial statements in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud.

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. Our procedures included confirmation of securities owned as of February 28, 2025 by correspondence with the custodian, transfer agent and broker. We believe that our audits provide a reasonable basis for our opinion.

/s/PricewaterhouseCoopers LLP

Minneapolis, Minnesota

April 22, 2025

We have served as the auditor of one or more investment companies within the Columbia Funds Complex since 1977.

Columbia Mid Cap Index Fund | 2025

Qualified dividend income	Dividends received deduction	Section 199A dividends	Capital gain dividend
44.71%	43.00%	11.11%	$216,608,315

(registrant)	Columbia Funds Series Trust

By (Signature and Title)	/s/ Daniel J. Beckman
	Daniel J. Beckman, President and Principal Executive Officer

Date	April 22, 2025