<PAGE>
CGM MUTUAL FUND
SUPPLEMENT DATED SEPTEMBER 24, 1996 TO
PROSPECTUS DATED MAY 1, 1996
On August 30, 1996, a new advisory agreement between CGM and CGM Mutual
Fund became effective in connection with the merger of New England Mutual Life
Insurance Company into Metropolitan Life Insurance Company. The new agreement,
which is identical to the prior agreement (other than the date of effectiveness
and termination), was approved by shareholders of CGM Mutual Fund on December
29, 1995.
In addition, on August 13, 1996, the Board of Trustees of CGM Mutual Fund
approved a proposed advisory agreement between CGM Mutual Fund and CGM that
would increase the advisory fee payable by CGM Mutual Fund to CGM to an annual
percentage rate of 0.90% of the first $500 million of CGM Mutual Fund's average
daily net asset value, 0.80% of the next $500 million of such value, and 0.75%
of such value in excess of $1 billion. The proposed advisory agreement is
subject to shareholder approval. A special meeting of shareholders of CGM Mutual
Fund to vote on the proposed advisory agreement will be held on December 12,
1996.
<PAGE>
CGM MUTUAL FUND
SUPPLEMENT DATED NOVEMBER 5, 1996 TO
PROSPECTUS DATED MAY 1, 1996
Residents of South Dakota who seek to exchange shares of CGM Mutual Fund
for shares of CGM Realty Fund should note that effective as of October 22, 1996,
shares of CGM Realty Fund are available for sale to residents of South Dakota.
<PAGE>
CGM MUTUAL FUND
SUPPLEMENT DATED NOVEMBER 5, 1996 TO
STATEMENT OF ADDITIONAL INFORMATION DATED MAY 1, 1996
Residents of South Dakota who seek to exchange shares of CGM Mutual Fund
for shares of CGM Realty Fund should note that effective as of October 22, 1996,
shares of CGM Realty Fund are available for sale to residents of South Dakota.
<PAGE>
CGM AMERICAN TAX FREE FUND
CGM FIXED INCOME FUND
Supplement Dated September 20, 1996 to
Prospectus dated May 1, 1996
CGM has voluntarily agreed to extend through December 31, 1997 and
thereafter until further notice to CGM American Tax Free Fund, its waiver of
management fees and agreement to bear all of the expenses of CGM American Tax
Free Fund.
<PAGE>
CGM AMERICAN TAX FREE FUND
CGM FIXED INCOME FUND
SUPPLEMENT DATED SEPTEMBER 24, 1996 TO
PROSPECTUS DATED MAY 1, 1996
On August 30, 1996, a new advisory agreement between CGM and CGM Fixed
Income Fund became effective in connection with the merger of New England Mutual
Life Insurance Company into Metropolitan Life Insurance Company. The new
agreement, which is identical to the prior agreement (other than the date of
effectiveness and termination), was approved by shareholders of CGM Fixed Income
Fund on December 29, 1995.
In addition, on August 13, 1996, the Board of Trustees of CGM Fixed Income
Fund approved a proposed advisory agreement between CGM Fixed Income Fund and
CGM that would increase the advisory fee payable by CGM Fixed Income Fund to CGM
to an annual percentage rate of 0.65% of the first $200 million of CGM Fixed
Income Fund's average daily net asset value, 0.55% of the next $300 million of
such value, and 0.40% of such value in excess of $500 million. In connection
with the proposed advisory fee increase, CGM has agreed to extend its commitment
to waive its advisory fee and, if necessary, limit certain expenses associated
with operating CGM Fixed Income Fund in order to limit CGM Fixed Income Fund's
operating expenses to an annual rate of 0.85% of its average net assets through
December 31, 1997 and to obtain approval of the Board of Trustees of CGM Fixed
Income Fund prior to any modification of this commitment thereafter. The
proposed advisory agreement is subject to shareholder approval. A special
meeting of shareholders of CGM Fixed Income Fund to vote on the proposed
advisory agreement will be held on December 12, 1996.
<PAGE>
CGM AMERICAN TAX FREE FUND
CGM FIXED INCOME FUND
SUPPLEMENT DATED NOVEMBER 5, 1996 TO
PROSPECTUS DATED MAY 1, 1996
Residents of South Dakota who seek to exchange shares of CGM Fixed Income
Fund or CGM American Tax Free Fund for shares of CGM Realty Fund should note
that effective as of October 22, 1996, shares of CGM Realty Fund are available
for sale to residents of South Dakota.
<PAGE>
CGM AMERICAN TAX FREE FUND
CGM FIXED INCOME FUND
SUPPLEMENT DATED NOVEMBER 5, 1996 TO
STATEMENT OF ADDITIONAL INFORMATION DATED MAY 1, 1996
Residents of South Dakota who seek to exchange shares of CGM Fixed Income
Fund or CGM American Tax Free Fund for shares of CGM Realty Fund should note
that effective as of October 22, 1996, shares of CGM Realty Fund are available
for sale to residents of South Dakota.
<PAGE>
CGM REALTY FUND
SUPPLEMENT DATED NOVEMBER 5, 1996 TO
PROSPECTUS DATED MAY 1, 1996
Effective as of October 22, 1996, the shares of CGM Realty Fund are
available for sale to residents of South Dakota.
<PAGE>
CGM REALTY FUND
SUPPLEMENT DATED NOVEMBER 5, 1996 TO
STATEMENT OF ADDITIONAL INFORMATION DATED MAY 1, 1996
Effective as of October 22, 1996, the shares of CGM Realty Fund are
available for sale to residents of South Dakota.
