AMERICAN CENTURY GOVERNMENT INCOME TRUST
PROSPECTUS SUPPLEMENT (INVESTOR CLASS)
CAPITAL PRESERVATION * GOVERNMENT AGENCY MONEY MARKET
SHORT-TERM TREASURY * INTERMEDIATE-TERM TREASURY * LONG-TERM TREASURY
INFLATION-ADJUSTED TREASURY * SHORT-TERM GOVERNMENT * GNMA
Supplement dated November 1, 1999 * Prospectus dated August 1, 1999
The following should replace the chart under "What are the funds' primary
investment strategies and principal risks?" on page 2 of the Investor Class
Prospectus.
<TABLE>
Fund Primary Investments Principal Risks
- ---------------------------------------------------------------------------------------------------
<S> <C> <C>
Capital Preservation Very short-term U.S. Treasury securities Lowest interest rate risk
- ---------------------------------------------------------------------------------------------------
Government Agency Very short-term U.S. government securities Very low credit risk
Money Market Lowest interest rate risk
- ---------------------------------------------------------------------------------------------------
Short-Term Treasury U.S. Treasury securities that mature Low interest rate risk
in three years or less
- ---------------------------------------------------------------------------------------------------
Intermediate-Term U.S. Treasury securities that mature Interest rate risk
Treasury in three years or more
- ---------------------------------------------------------------------------------------------------
Long-Term Treasury U.S. Treasury securities that mature High interest rate risk
in 10 years or more
- ---------------------------------------------------------------------------------------------------
Short-Term Government U.S. government securities that mature Some credit risk
in three years or less Low interest rate risk
- ---------------------------------------------------------------------------------------------------
GNMA Fund Ginnie Maes, which are mortgage-backed Interest rate risk
securities issued by Government National Low credit risk
Mortgage Association
- ---------------------------------------------------------------------------------------------------
Inflation Adjusted Inflation-indexed U.S. Treasury securities Interest rate risk
Treasury
</TABLE>
The following replaces the highest and lowest quarterly return chart on page 3
of the Investor Class Prospectus.
The highest and lowest quarterly returns for the period reflected in the bar
chart are:
Highest Lowest
- --------------------------------------------------------------------------------
Capital Preservation 2.12% (2Q 1989) 0.63% (2Q 1993)
- --------------------------------------------------------------------------------
Government Agency Money Market 2.06% (1Q 1990) 0.65% (2Q 1993)
The following replaces the third paragraph on page 12 of the Investor Class
Prospectus.
The fund also may buy traditional U.S. Treasury securities that are not
inflation-indexed.
The fund also may buy inflation-indexed securities issued by the U.S. government
agencies and government-sponsored organizations. The fund may invest up to 35%
of its total assets in these securities.
The following replaces the third paragraph on page 14 of the Investor Class
Prospectus. The fifth paragraph on this page should be deleted.
The fund also may buy U.S. government securities. The U.S. government, its
agencies and instrumentalities issue these securities. These securities include
mortgage-backed securities. The U.S. government's financial support of these
agencies and instrumentalities varies.
The section entitled "Inflation Risk" on page 16 of the Investor Class
Prospectus should be deleted.
The last column entitled "Inflation Risk" in the chart on page 17 of the
Investor Class Prospectus should be deleted.
The following replaces the fifth paragraph on page 19 of the Investor Class
Prospectus.
CASEY COLTON
Mr. Colton, Vice President and Portfolio Manager, has been a member of the GNMA
team since January 1994. Mr. Colton joined American Century in 1990. He holds a
bachelor's degree in business administration from San Jose State University and
a master's degree from the University of Southern California. He is a Chartered
Financial Analyst and a Certified Public Accountant.
SH-SPL-18583 9911
<PAGE>
AMERICAN CENTURY GOVERNMENT INCOME TRUST
PROSPECTUS SUPPLEMENT (ADVISOR CLASS)
GOVERNMENT AGENCY MONEY MARKET * SHORT-TERM TREASURY
INTERMEDIATE-TERM TREASURY * LONG-TERM TREASURY
INFLATION-ADJUSTED TREASURY * SHORT-TERM GOVERNMENT * GNMA
Supplement dated November 1, 1999 * Prospectus dated August 1, 1999
The following should replace the chart under "What are the funds' primary
investment strategies and principal risks?" on page 2 of the Advisor Class
Prospectus.
<TABLE>
Fund Primary Investments Principal Risks
- ------------------------------------------------------------------------------------------------------
<S> <C> <C>
Government Agency Very short-term U.S. government securities Very low credit risk
Money Market Lowest interest rate risk
- ------------------------------------------------------------------------------------------------------
Short-Term Treasury U.S. Treasury securities that mature Low interest rate risk
in three years or less
- ------------------------------------------------------------------------------------------------------
Intermediate-Term U.S. Treasury securities that mature Interest rate risk
Treasury in three years or more
- ------------------------------------------------------------------------------------------------------
Long-Term Treasury U.S. Treasury securities that mature High interest rate risk
in 10 years or more
- ------------------------------------------------------------------------------------------------------
Short-Term Government U.S. government securities that mature Some credit risk
in three years or less Low interest rate risk
- ------------------------------------------------------------------------------------------------------
GNMA Fund Ginnie Maes, which are mortgage-backed Interest rate risk
securities issued by Government National Low credit risk
Mortgage Association
- ------------------------------------------------------------------------------------------------------
Inflation Adjusted Inflation-indexed U.S. Treasury securities Interest rate risk
Treasury
</TABLE>
The following replaces the section "What is the difference between the three
funds?" on page 7 of the Advisor Class Prospectus.
WHAT IS THE DIFFERENCE BETWEEN THE THREE FUNDS?
The funds differ in the maturity of the debt securities they purchase. This
difference is shown in the chart below.
Expected Weighted Average Maturity Range
- --------------------------------------------------------------------------------
Short-Term Treasury 13 months-3 years
- --------------------------------------------------------------------------------
Intermediate-Term Treasury 3-10 years
- --------------------------------------------------------------------------------
Long-Term Treasury 10-30 years
The following replaces the third paragraph on page 8 of the Advisor Class
Prospectus.
The fund also may buy traditional U.S. Treasury securities that are not
inflation-indexed.
The fund also may buy inflation-indexed securities issued by the U.S. government
agencies and government-sponsored organizations. The fund may invest up to 35%
of its total assets in these securities.
The following replaces the third paragraph on page 10 of the Advisor Class
Prospectus. The fifth paragraph on this page should be deleted.
The fund also may buy U.S. government securities. The U.S. government, its
agencies and instrumentalities issue these securities. These securities include
mortgage-backed securities. The U.S. government's financial support of these
agencies and instrumentalities varies.
The section entitled "Inflation Risk" on page 12 of the Advisor Class Prospectus
should be deleted.
The last column entitled "Inflation Risk" in the chart on page 13 of the Advisor
Class Prospectus should be deleted.
The following replaces the fifth paragraph on page 15 of the Advisor Class
Prospectus.
CASEY COLTON
Mr. Colton, Vice President and Portfolio Manager, has been a member of the GNMA
team since January 1994. Mr. Colton joined American Century in 1990. He holds a
bachelor's degree in business administration from San Jose State University and
a master's degree from the University of Southern California. He is a Chartered
Financial Analyst and a Certified Public Accountant.
SH-SPL-18639 9911
