Exhibit
4.2


 


	NUMBER
    C-	SHARES
	SEE
    REVERSE FOR CERTAIN DEFINITIONS	 
	 	CUSIP
    349885 103


 


FORUM
MERGER III CORPORATION


CLASS
A COMMON STOCK


 


THIS
CERTIFIES THAT                is the owner of
               fully paid and non-assessable shares
of Class A common stock, par value $0.0001 per share (the “Common Stock”), of Forum Merger III Corporation,
a Delaware corporation (the “Company”), transferable on the books of the Company in person or by duly
authorized attorney upon surrender of this certificate properly endorsed.


 


This
certificate is not valid unless countersigned by the Transfer Agent and registered by the Registrar of the Company.


 


Witness
the facsimile signature of a duly authorized signatory of the Company.


 


 


	Authorized
    Signatory	 	Transfer
    Agent


 




     

     


    

 


FORUM
MERGER III CORPORATION


 


The
Company will furnish without charge to each stockholder who so requests, a statement of the powers, designations, preferences
and relative, participating, optional or other special rights of each class of equity or series thereof of the Company and the
qualifications, limitations, or restrictions of such preferences and/or rights. This certificate and the shares represented thereby
are issued and shall be held subject to all the provisions of the Company’s Amended and Restated Certificate of Incorporation
and all amendments thereto and resolutions of the Board of Directors providing for the issue of securities (copies of which may
be obtained from the secretary of the Company), to all of which the holder of this certificate by acceptance hereof assents.


 


The
following abbreviations, when used in the inscription on the face of this certificate, shall be construed as though they were
written out in full according to applicable laws or regulations:


  


	TEN COM	—
    	 	as tenants in common	 	UNIF GIFT MIN ACT	—
    	___________ Custodian ___________
	 	 	 	 	 	 	 	      (Cust)                             (Minor)
	TEN ENT	—	 	as tenants by the entireties	 	 	 	 
	 	 	 	 	 	 	 	Under Uniform Gifts to Minors Act
	JT TEN	—	 	as joint tenants with right of survivorship
    and not as tenants in common	 	 	 	_____________________________

        (State)



  


Additional
abbreviations may also be used though not in the above list.


 


For
value received, hereby sells, assigns and transfers unto


 


(PLEASE
INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER(S) OF ASSIGNEE(S))


 


(PLEASE
PRINT OR TYPEWRITE NAME(S) AND ADDRESS(ES), INCLUDING ZIP CODE, OF ASSIGNEE(S))


 


shares
of Common Stock represented by the within Certificate, and hereby irrevocably constitutes and appoints


 


Attorney
to transfer the said shares of Common Stock on the books of the within named Company with full power of substitution in the premises.





 


	Dated:	 
	 	Notice:
    The signature(s) to this assignment must correspond with the name as written upon the face of the certificate in every
    particular, without alteration or enlargement or any change whatever.





 






    	 	2	 



     


    




 


Signature(s)
Guaranteed: 


	 	 
	THE
    SIGNATURE(S) MUST BE GUARANTEED BY AN ELIGIBLE GUARANTOR INSTITUTION (BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS AND
    CREDIT UNIONS WITH MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE MEDALLION PROGRAM, PURSUANT TO S.E.C. RULE 17Ad-15 UNDER
    THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED (OR ANY SUCCESSOR RULE).	 


 


As
more fully described in, and subject to the terms and conditions described in, the Company’s final prospectus for its initial
public offering dated, 2020, the holder(s) of this certificate shall be entitled to receive a pro rata portion of certain funds
held in the trust account established in connection with the Company’s initial public offering only in the event that (i)
the Company redeems the shares of Common Stock sold in the Company’s initial public offering and liquidates because it does
not consummate an initial business combination by the date set forth (the “Last Date”) in the Company’s Amended
and Restated Certificate of Incorporation, as the same may be amended from time to time (the “Charter”), (ii) the
Company redeems the shares of Common Stock sold in its initial public offering properly submitted in connection with a stockholder
vote to amend the Charter to modify the substance or timing of the Company’s obligation to redeem 100% of the Common Stock
if it does not consummate an initial business combination by the Last Date or with respect to any other material provisions relating
to stockholders’ rights or pre-initial business combination activity, or (iii) if the holder(s) seek(s) to redeem for cash
his, her or its respective shares of Common Stock in connection with a tender offer (or proxy solicitation, solely in the event
the Company seeks stockholder approval of the proposed initial business combination) setting forth the details of a proposed initial
business combination. In no other circumstances shall the holder(s) have any right or interest of any kind in or to the trust
account.


 


 


3