UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
 Washington, D.C. 20549

SCHEDULE 14A INFORMATION
 Proxy Statement Pursuant to Section 14(a) of
the Securities Exchange Act of 1934

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| | Definitive Proxy Statement

|X| Definitive Additional Materials

| | Soliciting Material Pursuant to Rule 14a-12

PIONEER DIVERSIFIED HIGH INCOME FUND, INC. (HNW)
PIONEER FLOATING RATE FUND, INC. (PHD)
 PIONEER HIGH INCOME FUND, INC. (PHT)
 PIONEER MUNICIPAL HIGH INCOME FUND, INC. (MHI)
PIONEER MUNICIPAL HIGH INCOME ADVANTAGE FUND, INC. (MAV)
(Name of Registrant(s) as Specified In Its Charter)

N/A
(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

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LOGO

August 20, 2021

PIONEER DIVERSIFIED HIGH INCOME FUND, INC. (HNW)
PIONEER FLOATING RATE FUND, INC. (PHD)
PIONEER HIGH INCOME FUND, INC. (PHT)
PIONEER MUNICIPAL HIGH INCOME FUND, INC. (MHI)
PIONEER MUNICIPAL HIGH INCOME ADVANTAGE FUND, INC. (MAV)

DEAR FELLOW STOCKHOLDER:

As an investor in one or more of the above Pioneer Closed-End Funds ("Funds"), we have sent you proxy communications in connection with electing the Funds' nominees to the Board of Directors at the Annual Meeting of Stockholders scheduled to be held on September 15, 2021.

I am pleased to report that your fellow stockholders have responded. Please support the election of your highly qualified and experienced nominees. Please join your fellow stockholders by taking a few moments to sign, date and mail the enclosed card in the prepaid envelope or follow the instructions below to vote by telephone or internet.

LOGO  Vote by Phone by calling 1-833-459-3559 and speaking with a proxy voting
      specialist today. Our representatives are available weekdays from 10
      a.m. to 11 p.m. Eastern time. You may also call the toll-free number on
      the enclosed card and follow the prompts.

LOGO  Vote by Internet by visiting the internet address on the enclosed card
      and following the instructions.

LOGO  Vote by Mail by completing, signing, and dating the enclosed card and
      returning it in the enclosed prepaid return envelope.

Our proxy solicitor, Di Costa Partners ("DCP"), may call you to answer any question you may have regarding the proxy and to assist you in voting. You can call DCP at 1-833-459-3559 during normal business hours, Monday - Friday, 10:00
a.m. - 11:00 p.m., Eastern if you have any questions regarding the proxy.

Thank you in advance for your vote,

LOGO

LISA M. JONES
PRESIDENT AND CHIEF EXECUTIVE OFFICER
PIONEER FUNDS

AAM_R2_0921

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