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 January 18, 2000 * Prospectus dated August 1, 1999
The following replaces the paragraph and chart under "What are the funds'
primary investment strategies and principal risks?" on page 2 of the Investor
Class Prospectus.
The funds invest most of their assets in debt securities issued by the U.S.
government or its agencies or instrumentalities. The following chart shows the
differences among the funds' primary investments and principal risks. It is
designed to help you compare these funds with each other; it should not be used
to compare these funds with other mutual funds. A more detailed description of
the funds' investment strategies and risks begins on page 10.
Fund Primary Investments Principal Risks
------------------------------------------------------------------------------
Capital Preservation Very short-term U.S. Lowest interest
Treasury securities rate risk
Government Agency Very short-term U.S.
Money Market government securities Lowest credit risk
Lowest interest
rate risk
Short-Term Treasury U.S. Treasury securities Low interest rate
that mature in three years risk
or less
Intermediate-Term U.S. Treasury securities that Moderate interest
Treasury mature in three years or more rate risk
Long-Term Treasury U.S. Treasury securities that High interest
mature in 10 years or more rate risk
Short-Term Government U.S. government securities that Low credit risk
mature in three years or less
Low interest rate
risk
GNMA Fund Ginnie Maes, which are mortgage- High interest
backed securities issued rate risk
by Government National
Mortgage Association Low credit risk
Inflation-Adjusted Inflation-indexed U.S. Treasury Moderate interest
Treasury securities rate risk
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 may buy traditional U.S. Treasury securities that are not
inflation-indexed.
In addition, 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 is 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 is deleted.
The last column entitled "Inflation Risk" in the chart on page 17 of the
Investor Class Prospectus is 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.
The following replaces the seventh paragraph on page 19 of the Investor Class
Prospectus.
David W. Schroeder
Mr. Schroeder, Vice President and Portfolio Manager, supervises the American
Century Government Income Trust team and has been a member of the Short-Term
Treasury team since 1992 and the Short-Term Government team since 1995. He also
is a member of the Intermediate-Term Treasury, Long-Term Treasury and
Inflation-Adjusted Treasury teams. He joined American Century in 1990. He holds
a bachelor of arts from Pomona College.
Robert V. Gahagan
Mr. Gahagan, Vice President and Portfolio Manager, has been a member of the
Short-Term Treasury team since 1996 and the Short-Term Government team since
1990. He is also a member of the Intermediate-Term Treasury team. He joined
American Century in 1983. He holds a bachelor's degree in economics and an MBA
from the University of Missouri-Kansas City.
Michael J. Shearer
Mr. Shearer, Vice President and Director-Fixed-Income Quantitative Strategies,
has been a member of the Short-Term Government team since January 2000. He also
is responsible for the development and implementation of all fixed-income
quantitative strategies. He joined American Century in February 1998. Before
joining American Century, he was Vice President, Quantitative Research at
Capital Management Sciences from November 1995 to February 1998. Prior to that
he was pursuing and received a doctorate in mathematics from the University of
California-Los Angeles. He also holds a bachelor's degree in applied mathematics
and a master's degree in mathematics from UCLA.
SH-SPL-19271 0001
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 January 18, 2000 * Prospectus dated August 1, 1999
The following replaces the paragraph and chart under "What are the funds'
primary investment strategies and principal risks?" on page 2 of the Advisor
Class Prospectus.
The funds invest most of their assets in debt securities issued by the U.S.
government or its agencies or instrumentalities. The following chart shows the
differences among the funds' primary investments and principal risks. It is
designed to help you compare these funds with each other; it should not be used
to compare these funds with other mutual funds. A more detailed description of
the funds' investment strategies and risks begins on page 6.
Fund Primary Investments Principal Risks
-------------------------------------------------------------------------------
Government Agency Very short-term U.S. government Lowest credit
Money Market securities risk
Lowest interest
rate risk
Short-Term Treasury U.S. Treasury securities that Low interest
mature in three years or less rate risk
Intermediate-Term U.S. Treasury securities that Moderate interest
Treasury mature in three years or more rate risk
Long-Term Treasury U.S. Treasury securities that High interest
mature in 10 years or more rate risk
Short-Term Government U.S. government securities that Low credit risk
mature in three years or less
Low interest
rate risk
GNMA Fund Ginnie Maes, which are mortgage- High interest
backed securities rate risk
issued by Government National
Mortgage Association Low credit risk
Inflation-Adjusted Inflation-indexed Moderate interest
Treasury securities U.S. Treasury rate risk
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 may buy traditional U.S. Treasury securities that are not
inflation-indexed.
In addition, 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 is 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
is deleted.
The last column entitled "Inflation Risk" in the chart on page 13 of the Advisor
Class Prospectus is 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.
The following replaces the seventh paragraph on page 15 of the Advisor Class
Prospectus.
DAVID W. SCHROEDER
Mr. Schroeder, Vice President and Portfolio Manager, supervises the American
Century Government Income Trust team and has been a member of the Short-Term
Treasury team since 1992 and the Short-Term Government team since 1995. He also
is a member of the Intermediate-Term Treasury, Long-Term Treasury and
Inflation-Adjusted Treasury teams. He joined American Century in 1990. He holds
a bachelor of arts from Pomona College.
ROBERT V. GAHAGAN
Mr. Gahagan, Vice President and Portfolio Manager, has been a member of the
Short-Term Treasury team since 1996 and the Short-Term Government team since
1990. He is also a member of the Intermediate-Term Treasury team. He joined
American Century in 1983. He holds a bachelor's degree in economics and an MBA
from the University of Missouri-Kansas City.
MICHAEL J. SHEARER
Mr. Shearer, Vice President and Director-Fixed-Income Quantitative Strategies,
has been a member of the Short-Term Government team since January 2000. He also
is responsible for the development and implementation of all fixed-income
quantitative strategies. He joined American Century in February 1998. Before
joining American Century, he was Vice President, Quantitative Research at
Capital Management Sciences from November 1995 to February 1998. Prior to that
he was pursuing and received a doctorate in mathematics from the University of
California-Los Angeles. He also holds a bachelor's degree in applied mathematics
and a master's degree in mathematics from UCLA.
SH-SPL-19479 0001
