Sec Form 4 Filing - Liu Suying @ Mountain Crest Acquisition Corp. III - 2021-06-14

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 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(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Liu Suying 2. Issuer Name and Ticker or Trading Symbol Mountain Crest Acquisition Corp. III [ MCAEU] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner X __ Officer (give title below) _____ Other (specify below) CEO and CFO (Last) (First) (Middle) 311 WEST 43RD STREET, 12TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 06/14/2021 (Street) NEW YORK, NY10036 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 06/14/2021 P 2,086 ( 1 ) A $ 10 1,543,586 I See Footnote ( 2 ) Common Stock 06/14/2021 J( 5 ) 83,202 D 1,460,384 I See Footnote ( 2 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Rights to purchase Common Stock $ 0 06/14/2021 P 2,086 ( 3 ) ( 3 ) Common Stock 208 ( 1 ) 2,086 I See Footnote ( 4 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Liu Suying 311 WEST 43RD STREET, 12TH FLOOR NEW YORK, NY10036 X X CEO and CFO Signatures /s/ Suying Liu 06/16/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The reporting person acquired units, consisting of shares and rights. ( 2 )Shares owned by Mountain Crest Holdings III LLC, over which Suying Liu owns sole voting and dispositive power. ( 3 )The rights automatically convert into one-tenth (1/10) of a share of common stock upon the consummation of the registrant's initial business combination, as described in the registrant's prospectus filed with the SEC. ( 4 )Rights underlying the units owned by Mountain Crest Holdings III LLC, over which Suying Liu owns sole voting and dispositive power. ( 5 )On June 14, 2021, the underwriters of Mountain Crest Acquisition Corp III (the "Company") exercised the over-allotment option in part and canceled the remainder of the over-allotment option. In connection with the cancellation of the remainder of the over-allotment option, the Company has canceled an aggregate of 83,202 shares of common stock issued to Mountain Crest Holdings III LLC prior to its IPO and private placement.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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