Exhibit 4.2


 


	 	NUMBER	SHARES
	 	 	 
	 	______C	 


 


ALLEGRO MERGER CORP.


 


INCORPORATED UNDER
THE LAWS OF DELAWARE


 


COMMON STOCK


 


SEE REVERSE FOR

CERTAIN DEFINITIONS


 


	 	This Certifies that	CUSIP 01749N 103
	 	 	 
	 	is the owner of	 


 


FULLY PAID AND NON-ASSESSABLE
SHARES OF COMMON STOCK OF THE PAR VALUE OF $.0001 EACH OF


 


ALLEGRO MERGER CORP.


 


transferable on the
books of the Company in person or by duly authorized attorney upon surrender of this certificate properly endorsed. 


The Company will be
forced to liquidate if it is unable to complete an initial business combination within the time period set forth in the Company’s
amended and restated certificate of incorporation, as the same may be amended from time to time, all as more fully described in
the Company’s final prospectus dated ________, 2018.

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

Witness the facsimile seal of the Company and the facsimile signatures of its duly authorized officers.


 


            
Dated:


 


	 	 		 
	 	 	 
	 	 	 
	 	CHAIRMAN	SECRETARY
	 	 	 
	 	 	 




 



     


     


    

 


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 ______
	 	TEN ENT –	as tenants by the entireties	  (Cust)                    (Minor)
	 	JT TEN –	as joint tenants with right of survivorship	 under Uniform Gifts to Minors
	 	 	and not as tenants in common	 Act ______________
	 	 	 	                   (State)


 


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


 


Allegro Merger Corp.


 


The Company will furnish
without charge to each shareholder who so requests the powers, designations, preferences and relative, participating, optional
or other special rights of each class of stock 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 Certificate of Incorporation and all amendments thereto and resolutions of the Board of Directors (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.


 


For value received, ___________________________
hereby sell, assign and transfer unto


 


PLEASE INSERT SOCIAL SECURITY OR OTHER


IDENTIFYING NUMBER OF ASSIGNEE


 


	 	 
	 	 



 


 


 






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


 


 


 






 


	 	  shares


 


of the capital stock represented by
the within Certificate, and do hereby irrevocably constitute and appoint


 


	 	  Attorney


to transfer the said stock on the books
of the within named Company will full power of substitution in the premises.


 


	Dated	 	 


 


	 	 	 
	 	Notice:	The signature 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.


 


Signature(s) Guaranteed:


 


 


 






THE SIGNATURE(S) SHOULD 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).


 


The holder(s) of this certificate shall be entitled to receive
a pro-rata portion of the funds from the trust account only in the event that (i) the Corporation is forced to liquidate because
it does not consummate an initial business combination within the period of time set forth in the Corporation’s Amended and
Restated Certificate of Incorporation, as the same may be amended from time to time (the “Charter”) or (ii) if the
holder seeks to convert his shares upon consummation of, or sell his shares in a tender offer in connection with, an initial business
combination or in connection with certain amendments to the Charter. In no other circumstances shall the holder(s) have any right
or interest of any kind in or to the trust account.