SUPPLEMENT TO CURRENT PROSPECTUS AND
                      STATEMENT OF ADDITIONAL INFORMATION
                                       OF
               KEYSTONE CUSTODIAN FUND, SERIES B-4 (THE "FUND")

    The Fund's  Board of  Trustees  has  approved a change in the Fund's name to
"Keystone High Income Bond Fund (B-4)" effective May 1, 1995.

    In addition,  effective  May 1, 1995,  the section of the Fund's  prospectus
entitled  "Fund  Objective and Policies" is hereby  supplemented  to reflect the
following  change (to be inserted  in place of the second  sentence of the first
paragraph):

        "The Fund will invest, under normal  circumstances,  at least 65% of its
    total  assets in bonds,  debentures  and other income  obligations,  and its
    portfolio ordinarily includes a substantial number of bonds,  debentures and
    other income  obligations,  which,  as a class,  sell at discounts  from par
    value and are rated by  Standard  & Poor's  Corporation  ("S&P")  or Moody's
    Investors  Service,  Inc.  ("Moody's") as below investment grade,  i.e., S&P
    rating  below BBB and  Moody's  rating  below  Baa.

    The name of the Fund's investment adviser and certain of its affiliates will
also be  changed,  effective  May 1,  1995.  The name of the  Fund's  investment
adviser will become "Keystone Investment  Management  Company",  the name of its
principal underwriter will become "Keystone Investment Distributors Company" and
the name of their parent company will become "Keystone Investments, Inc."

    Furthermore,  the  Fund's  Board of  Trustees  has  approved a change in the
Fund's  dividend  payment  schedule  from  quarterly  distributions  to  monthly
distributions  commencing in July, 1995 with the last quarterly  distribution to
occur in June,  1995.  Accordingly,  effective  July 1, 1995, the section of the
Fund's  prospectus  entitled  "Dividends  and Taxes" is hereby  supplemented  to
reflect the  following  change (to be inserted in place of the last  sentence of
the first paragraph):

        "The Fund will make  distributions  from its net investment income on or
    about the 5th day of each  month and net  capital  gains,  if any,  at least
    annually."

    Finally,  the Fund's prospectus and statement of additional  information are
hereby supplemented as follows:

        "Contingent  deferred sales charges will now be waived on any redemption
    consisting  of (1) loan  proceeds  to a  retirement  plan  participant;  (2)
    financial hardship withdrawals made by a retirement plan participant; or (3)
    returns  of  excess  contributions  or  excess  deferral  amounts  made to a
    retirement plan participant."



April 28, 1995

                                                                           B4-SK