June 11, 1999
SUPPLEMENT TO THE PROSPECTUS OF
PIONEER MID-CAP FUND
DATED FEBRUARY 1, 1999
The following information supplements the corresponding section in the
prospectus. Please consult the prospectus for the full text of the revised
section.
BASIC INFORMATION ABOUT THE FUND
INVESTMENT STRATEGIES
On April 30, 1999, the market value of companies in Standard & Poor's MidCap 400
Index varied from approximately $202 million to over $14 billion.
MANAGEMENT
PORTFOLIO MANAGER
Effective June 1, 1999, day-to-day management of the fund's portfolio is the
responsibility of Eric J. Weigel, a senior vice president of Pioneer, who
co-managed the fund's investments since January 1999. Mr. Weigel joined Pioneer
in 1998 and has been an investment professional since 1989. Prior to joining
Pioneer, Mr. Weigel was head of global asset allocation and portfolio manager at
Chancellor LGT Asset Management from 1994 to 1997 and managed domestic and
international portfolios for INVESCO Management and Research from 1993 to 1994.
Mr. Weigel and his supporting analysts who specialize in U.S. equity
securities are led by Richard E. Dahlberg, a managing director of Pioneer. Mr.
Dahlberg joined Pioneer in 1998 and has been an investment professional since
1960. This team provides research for the fund and other Pioneer mutual funds
with similar investment objectives or styles. The investment team operates under
the supervision of Theresa A. Hamacher. Ms. Hamacher is chief investment officer
of Pioneer. She joined Pioneer in 1997 and has been an investment professional
since 1984; most recently as chief investment officer at another investment
adviser.
0699-6667
(C) Pioneer Funds Distributor, Inc.
