January 6, 2021

VIA EDGAR

United States Securities and Exchange Commission
Division of Corporation Finance
100 F Street, N.E.
Washington, D.C. 20549
Attention: Irene Barberena-Meissner

Re: Pioneer Merger Corp.
Registration Statement on Form S-1
Filed December 21, 2020, as amended
File No. 333-251556

Dear Ms. Barberena-Meissner:

Pursuant to Rule 461 of the General Rules and Regulations under the Securities Act of 1933, as amended (the “Act”), the undersigned hereby joins in the request of Pioneer Merger Corp. that the effective date of the above-referenced Registration Statement be accelerated so as to permit it to become effective at 4:00 p.m. Washington D.C. time on January 7, 2021, or as soon thereafter as practicable.

Pursuant to Rule 460 of the General Rules and Regulations under the Act, the undersigned advises that, as of the date hereof, they have distributed approximately 300 copies of the Preliminary Prospectus dated December 30, 2020 to prospective underwriters and dealers, institutional investors, retail investors and others.

The undersigned advises that it has complied and will continue to comply with the requirements of Rule 15c2-8 under the Securities Exchange Act of 1934, as amended.

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Very truly yours,
CITIGROUP GLOBAL MARKETS INC.
By:	/s/ John Eydenberg
	Name:   John Eydenberg
	Title:     Managing Director

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