4 1 west.txt STEPHEN WEST U.S. SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 FORM 4 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(f) of the Investment Company Act of 1940 [_] Check box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b). -------------------------------------------------------------------------------- 1. Name and Address of Reporting Person* West Stephen K. -------------------------------------------------------------------------------- (Last) (First) (Middle) c/o Sullivan & Cromwell 125 Broad Street -------------------------------------------------------------------------------- (Street) New York NY 10004 -------------------------------------------------------------------------------- (City) (State) (Zip) Pioneer Interest Shares, Inc. (MUO) -------------------------------------------------------------------------------- 2. Issuer Name and Ticker or Trading Symbol -------------------------------------------------------------------------------- 3. IRS Identification Number of Reporting Person, if an Entity (Voluntary) March 2001 -------------------------------------------------------------------------------- 4. Statement for Month/Year -------------------------------------------------------------------------------- 5. If Amendment, Date of Original (Month/Year) -------------------------------------------------------------------------------- 6. Relationship of Reporting Person to Issuer (Check all applicable) [X] Director [_] 10% Owner [_] Officer (give title below) [_] Other (specify below) -------------------------------------------------------------------------------- 7. Individual or Joint/Group Filing (Check applicable line) [X] Form filed by one Reporting Person [_] Form filed by more than one Reporting Person -------------------------------------------------------------------------------- ================================================================================ Table I -- Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned ================================================================================

* If the Form is filed by more than one Reporting Person, see Instruction 4(b)(v). Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. (Print or Type Response) (Over) FORM 4 (continued) Table II -- Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities) ================================================================================

Explanation of Responses: /s/ Stephen K. West April 3, 2001 --------------------------------------------- ----------------------- **Signature of Reporting Person Date ** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a). Note: File three copies of this Form, one of which must be manually signed. If space provided is insufficient, see Instruction 6 for procedure. Page 2

PIONEER INTEREST SHARES 4