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American Century Mutual Funds, Inc. Prospectus Supplement Select Fund
Supplement dated August 1, 2023 n Prospectus dated March 1, 2023

The following replaces the Fees and Expenses tables on page 2 of the prospectus:

Shareholder Fees (fees paid directly from your investment)

Investor

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

None

5.75%

None

Maximum Deferred Sales Charge (Load) (as a percentage of the lower of the original offering price or redemption proceeds when redeemed within one year of purchase)

None

None¹

1.00%

None

Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $10,000)

$25

None


Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
	Investor	I	Y	A	C	R	R5	R6
Management Fee	0.99%	0.79%	0.64%	0.99%	0.99%	0.99%	0.79%	0.64%
Distribution and Service (12b-1) Fees	None	None	None	0.25%	1.00%	0.50%	None	None
Other Expenses	0.01%	0.01%	0.01%	0.01%	0.01%	0.01%	0.01%	0.01%
Total Annual Fund Operating Expenses	1.00%	0.80%	0.65%	1.25%	2.00%	1.50%	0.80%	0.65%
Fee Waiver2	0.06%	0.06%	0.06%	0.06%	0.06%	0.06%	0.06%	0.06%
Total Annual Fund Operating Expenses After Fee Waiver	0.94%	0.74%	0.59%	1.19%	1.94%	1.44%	0.74%	0.59%

1 Purchases of $1 million or more may be subject to a contingent deferred sales charge of 1.00% if the shares are redeemed within one year of the date of the purchase.

2 The advisor has agreed to waive a portion of the fund’s management fee such that the management fee does not exceed 0.928% for Investor, A, C and R Classes, 0.728% for I and R5 Classes, and 0.578% for Y and R6 Classes. The advisor expects this waiver arrangement to continue until July 31, 2024 and cannot terminate it prior to such date without the approval of the Board of Directors.

The following replaces the Example section on pages 2 and 3 of the prospectus.

The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other mutual funds. The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same, except that it reflects the rate and duration of any fee waivers noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:


	1 year	3 years	5 years	10 years
Investor Class	$96	$313	$547	$1,219
I Class	$76	$250	$439	$985
Y Class	$60	$202	$357	$805
A Class	$690	$944	$1,217	$1,994
C Class	$197	$623	$1,073	$2,127
R Class	$147	$469	$814	$1,784
R5 Class	$76	$250	$439	$985
R6 Class	$60	$202	$357	$805


©2023 American Century Proprietary Holdings, Inc. All rights reserved. CL-SPL-98150 2308


American Century Mutual Funds, Inc. Prospectus Supplement Ultra Fund
Supplement dated August 1, 2023 n Prospectus dated March 1, 2023

The following replaces the Fees and Expenses tables on page 2 of the prospectus:

Shareholder Fees (fees paid directly from your investment)

Investor

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

None

5.75%

None

Maximum Deferred Sales Charge (Load) (as a percentage of the lower of the original offering price or redemption proceeds when redeemed within one year of purchase)

None

None¹

1.00%

None

Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $10,000)

$25

None


Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
	Investor	I	Y	A	C	R	R5	R6	G
Management Fee	0.95%	0.75%	0.60%	0.95%	0.95%	0.95%	0.75%	0.60%	0.60%
Distribution and Service (12b-1) Fees	None	None	None	0.25%	1.00%	0.50%	None	None	None
Other Expenses	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%
Total Annual Fund Operating Expenses	0.95%	0.75%	0.60%	1.20%	1.95%	1.45%	0.75%	0.60%	0.60%
Fee Waiver2	0.04%	0.04%	0.04%	0.04%	0.04%	0.04%	0.04%	0.04%	0.60%³
Total Annual Fund Operating Expenses After Fee Waiver	0.91%	0.71%	0.56%	1.16%	1.91%	1.41%	0.71%	0.56%	0.00%

1 Purchases of $1 million or more may be subject to a contingent deferred sales charge of 1.00% if the shares are redeemed within one year of the date of the purchase.

2 The advisor has agreed to waive a portion of the fund’s management fee such that the management fee does not exceed 0.911% for Investor, A, C and R Classes, 0.711% for I and R5 Classes, and 0.561% for Y and R6 Classes. The advisor expects this waiver arrangement to continue until July 31, 2024 and cannot terminate it prior to such date without the approval of the Board of Directors.

3 The advisor has agreed to waive the G Class’s management fee in its entirety. The advisor expects this waiver to remain in effect permanently and cannot terminate it without the approval of the Board of Directors.

The following replaces the Example section on pages 2 and 3 of the prospectus.


	1 year	3 years	5 years	10 years
Investor Class	$93	$299	$522	$1,163
I Class	$73	$236	$414	$927
Y Class	$57	$188	$331	$747
A Class	$687	$931	$1,194	$1,942
C Class	$194	$609	$1,049	$2,075
R Class	$144	$455	$789	$1,731
R5 Class	$73	$236	$414	$927
R6 Class	$57	$188	$331	$747
G Class	$0	$0	$0	$0


©2023 American Century Proprietary Holdings, Inc. All rights reserved. CL-SPL-98151 2308


American Century Mutual Funds, Inc. Prospectus Supplement Growth Fund
Supplement dated August 1, 2023 n Prospectus dated March 1, 2023

The following replaces the Fees and Expenses tables on page 2 of the prospectus:

Shareholder Fees (fees paid directly from your investment)

Investor

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

None

5.75%

None

Maximum Deferred Sales Charge (Load) (as a percentage of the lower of the original offering price or redemption proceeds when redeemed within one year of purchase)

None

None¹

1.00%

None

Maximum Annual Account Maintenance Fee (waived for unmatured Giftrust accounts or if eligible investments total at least $10,000)

$25

None


Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
	Investor	I	Y	A	C	R	R5	R6	G
Management Fee	0.97%	0.77%	0.62%	0.97%	0.97%	0.97%	0.77%	0.62%	0.62%
Distribution and Service (12b-1) Fees	None	None	None	0.25%	1.00%	0.50%	None	None	None
Other Expenses	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%
Total Annual Fund Operating Expenses	0.97%	0.77%	0.62%	1.22%	1.97%	1.47%	0.77%	0.62%	0.62%
Fee Waiver2	0.05%	0.05%	0.05%	0.05%	0.05%	0.05%	0.05%	0.05%	0.62%³
Total Annual Fund Operating Expenses After Fee Waiver	0.92%	0.72%	0.57%	1.17%	1.92%	1.42%	0.72%	0.57%	0.00%

1 Purchases of $1 million or more may be subject to a contingent deferred sales charge of 1.00% if the shares are redeemed within one year of the date of the purchase.

2 The advisor has agreed to waive a portion of the fund’s management fee such that the management fee does not exceed 0.915% for Investor, A, C and R Classes, 0.715% for I and R5 Classes, and 0.565% for Y and R6 Classes. The advisor expects this waiver arrangement to continue until July 31, 2024 and cannot terminate it prior to such date without the approval of the Board of Directors.

3 The advisor has agreed to waive the G Class’s management fee in its entirety. The advisor expects this fee waiver to remain in effect permanently and cannot terminate it without the approval of the Board of Directors.

The following replaces the Example section on pages 2 and 3 of the prospectus.


	1 year	3 years	5 years	10 years
Investor Class	$94	$305	$532	$1,185
I Class	$74	$241	$423	$950
Y Class	$58	$194	$341	$770
A Class	$688	$936	$1,203	$1,963
C Class	$195	$614	$1,059	$2,096
R Class	$145	$461	$799	$1,752
R5 Class	$74	$241	$423	$950
R6 Class	$58	$194	$341	$770
G Class	$0	$0	$0	$0


©2023 American Century Proprietary Holdings, Inc. All rights reserved. CL-SPL-98149 2308