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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| | Preliminary Proxy Statement

| | Confidential, for Use of the Commission Only (as permitted by Rule
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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) PIONEER MUNICIPAL HIGH INCOME OPPORTUNITIES FUND, INC. (MIO)

(Name of Registrant(s) as Specified In Its Charter)

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

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[LOGO]

August 23, 2022

PIONEER DIVERSIFIED HIGH INCOME FUND, INC.
PIONEER FLOATING RATE FUND, INC.
PIONEER HIGH INCOME FUND, INC.
PIONEER MUNICIPAL HIGH INCOME FUND, INC.
PIONEER MUNICIPAL HIGH INCOME ADVANTAGE FUND, INC.
PIONEER MUNICIPAL HIGH INCOME OPPORTUNITIES FUND, INC.

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, 2022.

I am pleased to report that your fellow stockholders have responded and are showing support for your Funds' nominees. However, your shares remain unvoted. Please join your fellow investors by supporting the election of your highly qualified and experienced nominees. Please take 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 1-866-761-2593 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 questions you may have regarding the proxy and to assist you in voting. You can call DCP at 1-866-761-2593 during normal business hours, Monday - Friday, 10:00a.m. - 11:00p.m., Eastern if you have any questions regarding the proxy.

Thank you in advance for your vote, 

/s/ Lisa M. Jones
-------------------

LISA M. JONES
PRESIDENT AND CHIEF EXECUTIVE OFFICER

PIONEER FUNDS

AAM_R2_0922

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