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			Before you invest, you may want to review the fund’s prospectus, which contains more information about the fund and its risks. You can find the fund’s prospectus, reports to shareholders, and other information about the fund online at the web addresses listed below. You can also get this information at no cost by calling or sending an email request. The fund’s prospectus and other information are also available from financial intermediaries (such as banks and broker-dealers) through which shares of the fund may be purchased or sold.

			Retail Investors americancentury.com/docs 1-800-345-2021 or 816-531-5575 prospectus@americancentury.com			Financial Professionals americancentury.com/fadocs 1-800-345-6488 advisor_prospectus@americancentury.com

			This summary prospectus incorporates by reference the fund's prospectus and statement of additional information (SAI), each dated August 1, 2026 (as supplemented at the time you receive this summary prospectus), as well as the Report of Independent Registered Public Accounting Firm and the financial statements included in the fund’s Form N-CSR for the fiscal year ended March 31, 2026. The fund’s SAI and N-CSR may be obtained, free of charge, in the same manner as the prospectus.

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for A Class sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in American Century Investments funds. More information about these and other discounts is available from your financial professional and in Calculation of Sales Charges on page 16 of the fund’s prospectus, Appendix A of the fund’s prospectus and Sales Charges in Appendix B of the statement of additional information.

Shareholder Fees (fees paid directly from your investment)

Investor

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

None

4.50%

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 $25,000 or shareholder has elected electronic delivery)

$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	0.59%	0.39%	0.36%	0.59%	0.59%	0.59%	0.39%	0.34%	0.34%
Distribution and Service (12b-1) Fees	None	None	None	0.25%	1.00%	0.50%	None	None	None
Other Expenses	0.01%	0.01%	0.01%	0.01%	0.01%	0.01%	0.01%	0.01%	0.01%
Total Annual Fund Operating Expenses	0.60%	0.40%	0.37%	0.85%	1.60%	1.10%	0.40%	0.35%	0.35%
Fee Waiver	None	None	None	None	None	None	None	None	0.34%²
Total Annual Fund Operating Expenses After Fee Waiver	0.60%	0.40%	0.37%	0.85%	1.60%	1.10%	0.40%	0.35%	0.01%

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	$61	$193	$335	$751
I Class	$41	$129	$225	$506
Y Class	$38	$119	$208	$469
A Class	$533	$709	$901	$1,452
C Class	$163	$506	$872	$1,698
R Class	$112	$350	$607	$1,340
R5 Class	$41	$129	$225	$506
R6 Class	$36	$113	$197	$444
G Class	$1	$3	$6	$13

The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was 161% of the average value of its portfolio.

Under normal market conditions, the fund invests at least 80% of its net assets in high- and medium-grade, non-money market debt securities. These securities, which may be payable in U.S. or foreign currencies, may include corporate bonds and notes, government securities, securities backed by mortgages or other assets, collateralized loan obligations, and collateralized mortgage obligations. Shorter-term debt securities round out the portfolio.

The fund invests most of its assets in investment-grade securities. An investment-grade security is one that has been rated by an independent rating agency in its top four credit quality categories or determined by the advisor to be of comparable credit quality. The weighted average maturity of the fund’s portfolio must be three and one-half years or longer.

The fund may invest in securities issued or guaranteed by the U.S. Treasury and certain U.S. government agencies or instrumentalities such as the Government National Mortgage Association (Ginnie Mae). Ginnie Mae is supported by the full faith and credit of the U.S. government. Securities issued or guaranteed by other U.S. government agencies or instrumentalities, such as the Federal National Mortgage Association (Fannie Mae), the Federal Home Loan Mortgage Corporation (Freddie Mac), and the Federal Home Loan Bank (FHLB) are not guaranteed by the U.S. Treasury or supported by the full faith and credit of the U.S. government. However, they are authorized to borrow from the U.S. Treasury to meet their obligations.

The fund also may invest in derivative instruments provided that such investments are in keeping with the fund’s investment objective. Such derivatives may include futures contracts, options on futures contracts, and swaps (including credit default swaps). The fund may use foreign currency exchange contracts to shift investment exposure from one currency into another for hedging purposes.

The portfolio managers select securities using an approach that integrates macroeconomic inputs, technical analysis of the relative value among various sectors, and fundamental research on individual securities. The macroeconomic framework provides interest rate and duration guidelines for the fund by analyzing economic activity, inflation, and monetary policy. Portfolio managers select individual securities using in-depth fundamental analysis designed to provide a detailed understanding of the credit worthiness of a security and its related market. As the market environment and investment opportunities change, portfolio managers buy and sell securities to meet the fund’s evolving sector allocations and credit quality standards.

The fund may engage in active and frequent trading of portfolio securities to achieve its principal investment strategies. This may cause higher transaction costs and may affect performance. It may also result in the realization and distribution of capital gains.

•Interest Rate Risk – Investments in debt securities are sensitive to interest rate changes. Generally, the value of debt securities and the funds that hold them decline as interest rates rise. This fund is more susceptible to interest rate changes than funds that have shorter-weighted maturities, such as money market and short-term bond funds. A period of rising interest rates may negatively affect the fund’s performance.

•Credit Risk – The inability or perceived inability of a security’s issuer to make interest and principal payments may cause the value of the security to decrease. As a result the fund’s share price could also decrease. Changes in the credit rating of a debt security held by the fund could have a similar effect.

•Prepayment and Extension Risk – The fund may invest in debt securities backed by mortgages or other assets. If these underlying assets are prepaid, the fund may benefit less from declining interest rates than funds of similar maturity that invest less heavily in mortgage- and asset-backed securities. Conversely, an issuer may exercise its right to pay principal on an obligation held by the fund later than expected (extend the obligation) especially in periods of rising interest rates. These events may lengthen the maturity and potentially reduce the value of these securities.

•Collateralized Obligations Risk – Collateralized obligations, such as collateralized loan obligations (CLOs), are subject to credit, interest rate, valuation, and prepayment and extension risks. These securities also are subject to risk of default on the underlying asset, particularly during periods of economic downturn. The market value of collateralized obligations may be affected by, among other things, changes in the market value of the underlying assets held by the collateralized obligations, changes in the distributions on the underlying assets, defaults and recoveries on the underlying assets, capital gains and losses on the underlying assets, prepayments on underlying assets and the availability, and prices and interest rates of underlying assets. Some of the collateralized obligations in which the fund invests may be covenant-lite loans. Covenant-lite loans contain fewer or less restrictive constraints on the borrower. The fund may have fewer rights against a borrower and an accompanying greater risk of loss when it invests in covenant-lite loans.

•Foreign Securities Risk – Foreign securities are generally riskier than U.S. securities. Political events (such as civil unrest, national elections and imposition of exchange controls), social and economic events (such as labor strikes and rising inflation), natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund’s investments in that country to experience losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities.

•Emerging Markets Risk – Investing in emerging market countries generally is also riskier than investing in foreign developed countries. Emerging market countries may have unstable governments and/or economies that are subject to sudden change, and significant volatility in their financial markets. These countries also may lack the legal, business and social framework to support securities markets.

•Derivatives Risk – The use of derivative instruments involves risks different from, or possibly greater than, the risks associated with investing directly in securities and other traditional instruments. Derivatives are subject to a number of risks, including liquidity, interest rate, market, credit and correlation risk. Derivatives used for hedging or risk management may not operate as intended, may expose the fund to other risks, and may be insufficient to protect the fund from the risks they were intended to hedge.

•Bank Loan Risk – The market for bank loans may not be highly liquid and the fund may have difficulty selling them. Bank loans may not be considered securities, thus the fund may not be afforded anti-fraud protections available under the federal securities laws. In connection with purchasing loan participations, the fund generally will have no right to enforce compliance by borrowers with loan terms nor any set off rights, and the fund may not benefit directly from any posted collateral. As a result, the fund may be subject to the credit risk of both the borrower and the lender selling the participation. Bank loan transactions may take more than seven days to settle, meaning that proceeds would be unavailable to make additional investments or meet redemptions.

•Liquidity Risk – During periods of market turbulence or unusually low trading activity, to meet redemptions it may be necessary for the fund to sell securities at prices that could have an adverse effect on the fund’s share price. Changing regulatory and market conditions, including increases in interest rates and credit spreads may adversely affect the liquidity of the fund’s investments.

•Market Risk – The value of securities owned by the fund may go up and down, sometimes rapidly or unpredictably. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.

• Redemption Risk – The fund may need to sell securities at times it would not otherwise do so in order to meet shareholder redemption requests. Selling securities to meet such redemptions may cause the fund to experience a loss, increase the fund’s transaction costs and/or have adverse tax consequences. Redemption activity can occur for many reasons, including shareholder reactions to market events or product changes. To the extent that a large shareholder (including the advisor, another account advised by the advisor, a fund of funds or 529 college savings plan) invests in the fund, the fund may experience relatively large redemptions as such shareholder reallocates its assets.

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for I Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com.


Average Annual Total Returns For the calendar year ended December 31, 2025	1 year	5 years	10 years	Since Inception	Inception Date
I Class Return Before Taxes	7.38%	-0.28%	1.99%	—	04/01/1993
Return After Taxes on Distributions	5.38%	-1.75%	0.63%	—	04/01/1993
Return After Taxes on Distributions and Sale of Fund Shares	4.34%	-0.83%	0.96%	—	04/01/1993
Investor Class Return Before Taxes	7.06%	-0.50%	1.77%	—	12/03/2001
Y Class1 Return Before Taxes	7.30%	-0.25%	2.02%	—	04/10/2017
A Class Return Before Taxes	1.99%	-1.66%	1.06%	—	12/03/2001
C Class2 Return Before Taxes	6.11%	-1.47%	0.91%	—	01/31/2003
R Class Return Before Taxes	6.53%	-0.99%	1.27%	—	07/29/2005
R5 Class3 Return Before Taxes	7.28%	-0.28%	1.99%	—	04/10/2017
R6 Class Return Before Taxes	7.32%	-0.25%	2.04%	—	07/26/2013
G Class Return Before Taxes	7.68%	—	—	2.96%	05/19/2022
Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)	7.30%	-0.36%	2.01%	—	—

1Historical performance for the Y Class prior to its inception is based on the performance of R6 Class shares. Y Class performance has been adjusted to reflect differences in expenses between classes. Since inception performance for the Y Class is based on the R6 Class inception date.

The after-tax returns are shown only for I Class shares. After-tax returns for other share classes will vary. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.

You may purchase or redeem shares of the fund on any business day through our website at americancentury.com, in person (at one of our Investor Centers), by mail (American Century Investments, P.O. Box 419200, Kansas City, MO 64141-6200), by telephone at 1-800-345-2021 (Investor Services Representative) or 1-800-345-3533 (Business, Not-For-Profit and Employer-Sponsored Retirement Plans), or through a financial intermediary. Shares may be purchased and redemption proceeds received by electronic bank transfer, by check or by wire.

Unless otherwise specified below, the minimum initial investment amount to open an account is $2,500 ($1,000 for Coverdell Education Savings Accounts and IRAs). However, American Century Investments will waive the fund minimum if you make an initial investment of at least $500 and continue to make automatic investments of at least $100 a month until reaching the fund minimum. Investors opening accounts through financial intermediaries may open an account with $250 for Investor, A, C and R Classes, but the financial intermediaries may require their clients to meet different investment minimums. The minimum may be waived for broker-dealer sponsored wrap program accounts, fee based accounts, and accounts through bank/trust and wealth management advisory organizations.

The minimum initial investment amount for the I Class is generally $5 million ($3 million for endowments and foundations), but the minimum may be waived if you have an aggregate investment in the American Century family of funds of $10 million or more ($5 million for endowments and foundations). This includes accounts held directly with American Century and those held through a financial intermediary.

For the Investor, A, C, R, R5 and R6 Classes, there is no minimum initial investment amount for certain employer-sponsored retirement plans, however, financial intermediaries or plan recordkeepers may require plans to meet different minimums. Employer-sponsored retirement plans are not eligible to invest in the I or Y Class.

G Class shares are available for purchase by other funds offered by American Century Investments for which it charges a management fee. In its sole discretion, American Century Investments may also make G Class shares available for purchase by other institutional clients for which American Century Investments provides investment management services for a fee pursuant to an investment advisory agreement. Currently, eligible clients are limited to commingled investment trusts or other pooled investment vehicles that utilize a target date or other asset allocation investment strategy for which American Century Investments provides asset allocation or glide path investment management services for a fee. G Class shares do not have a minimum purchase amount.

Fund distributions are generally taxable as ordinary income or capital gains, unless you are investing through a tax-deferred account such as a 401(k) or individual retirement account (in which case you may be taxed upon withdrawal of your investment from such account).

If you purchase the fund through a broker-dealer or other financial intermediary (such as a bank, insurance company, plan sponsor or financial professional), the fund and its related companies may pay the intermediary for the sale of fund shares and related services for investments in all classes except the Y, R6 and G Classes. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the fund over another investment. Ask your salesperson or visit your financial intermediary’s website for more information.