The fund invests primarily in zero-coupon U.S. Treasury securities and their equivalents, which can be subject to dramatic price fluctuations and could result in significant gains or losses if sold prior to maturity. Each Zero Coupon fund invests in different maturities of these debt securities and has different interest rate risks. The fund can only offer a relatively predictable return if held to maturity. Investment in zero-coupon securities is subject to greater price risk than interest-paying securities of similar maturity.

Although you can potentially earn a dependable return if you hold your shares to maturity, you should be prepared for dramatic price fluctuations which may result in significant gains or losses if sold prior to maturity.

Please see the prospectus for details about sales charges.

The gross expense ratio is the fund's total annual operating costs, expressed as a percentage of the fund's average net assets for a given time period. It is gross of any fee waivers or expense reimbursement. The net expense ratio is the expense ratio after the application of any waivers or reimbursement. This is the actual ratio that investors paid during the fund's most recent fiscal year. Please see the prospectus for more information.

Investor Class Shares: Minimum initial investment is $1,000 for IRA and CESA accounts, and $2,500 for non-retirement accounts, but these minimums are waived with an initial investment of at least $500 per account and automatic investments of at least $100 per month. Non-Retirement Accounts: If your account balance falls below the minimum, or if you cancel your automatic monthly investment plan prior to reaching the minimum, American Century Investments may redeem the account and send the proceeds to you. Prior to doing so, we will notify you and give you 90 days to meet the minimum or reinstate your automatic monthly investment plan.

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