Exhibit 4.3


 


[FACE]


 


Number


 


Warrants


  


THIS WARRANT SHALL BE VOID IF NOT EXERCISED
PRIOR TO

THE EXPIRATION OF THE EXERCISE PERIOD PROVIDED FOR

IN THE WARRANT AGREEMENT DESCRIBED BELOW


 


NEBULA ACQUISITION CORPORATION

 Incorporated Under the Laws of the State of Delaware


 


CUSIP 629076 118


 


Warrant Certificate


 


This Warrant Certificate certifies
that                                   ,
or registered assigns, is the registered holder of                       
warrant(s) evidenced hereby (the “Warrants” and each, a “Warrant”) to
purchase shares of Class A common stock, $0.0001 par value per share (“Common Stock”), of Nebula
Acquisition Corporation, a Delaware corporation (the “Company”).  Each Warrant entitles the holder,
upon exercise during the period set forth in the Warrant Agreement referred to below, to receive from the Company that number of
fully paid and non-assessable shares of Common Stock as set forth below, at the exercise price (the “Exercise Price”)
as determined pursuant to the Warrant Agreement, payable in lawful money (or through “cashless exercise”
as provided for in the Warrant Agreement) of the United States of America upon surrender of this Warrant Certificate and payment
of the Exercise Price at the office or agency of the Warrant Agent referred to below, subject to the conditions set forth herein
and in the Warrant Agreement.  Defined terms used in this Warrant Certificate but not defined herein shall have the meanings
given to them in the Warrant Agreement.


 


Each Warrant is initially exercisable for
one fully paid and non-assessable share of Common Stock.  The number of shares of Common Stock issuable upon exercise of the
Warrants is subject to adjustment upon the occurrence of certain events set forth in the Warrant Agreement.


 


The initial Exercise Price per share of
Common Stock for any Warrant is equal to $11.50 per share.  The Exercise Price is subject to adjustment upon the occurrence
of certain events set forth in the Warrant Agreement.


 


Subject to the conditions set forth in the
Warrant Agreement, the Warrants may be exercised only during the Exercise Period and to the extent not exercised by the end of
such Exercise Period, such Warrants shall become void.


 


Reference is hereby made to the further
provisions of this Warrant Certificate set forth on the reverse hereof and such further provisions shall for all purposes have
the same effect as though fully set forth at this place.


 


This Warrant Certificate shall not be valid
unless countersigned by the Warrant Agent, as such term is used in the Warrant Agreement.


 


This Warrant Certificate shall be governed
by and construed in accordance with the internal laws of the State of New York, without regard to conflicts of laws principles
thereof.


 






    	 	 	 



     


    

 


	 	NEBULA ACQUISITION CORPORATION
	 	 
	 	 
	 	By:	                          
	 	Name:	 
	 	Title:	 
	 	 
	 	 
	 	AMERICAN STOCK TRANSFER
	 	& TRUST COMPANY, LLC as Warrant Agent
	 	 
	 	 
	 	By:	 
	 	Name:	 
	 	Title:	 


 






    	 	2	 



     


    

 


[Reverse]


 


The Warrants evidenced by this Warrant Certificate
are part of a duly authorized issue of Warrants entitling the holder on exercise to receive                
shares of Common Stock and are issued or to be issued pursuant to a Warrant Agreement dated as of           ,
2018 (the “Warrant Agreement”), duly executed and delivered by the Company to American Stock Transfer &
Trust Company, LLC, a New York limited liability trust company, as warrant agent (the “Warrant Agent”),
which Warrant Agreement is hereby incorporated by reference in and made a part of this instrument and is hereby referred to for
a description of the rights, limitation of rights, obligations, duties and immunities thereunder of the Warrant Agent, the Company
and the holders (the words “holders” or “holder” meaning the Registered Holders
or Registered Holder) of the Warrants.  A copy of the Warrant Agreement may be obtained by the holder hereof upon written
request to the Company.  Defined terms used in this Warrant Certificate but not defined herein shall have the meanings given
to them in the Warrant Agreement.


 


Warrants may be exercised at any time during
the Exercise Period set forth in the Warrant Agreement.  The holder of Warrants evidenced by this Warrant Certificate may
exercise them by surrendering this Warrant Certificate, with the form of election to purchase set forth hereon properly completed
and executed, together with payment of the Exercise Price as specified in the Warrant Agreement (or through “cashless exercise”
as provided for in the Warrant Agreement) at the principal corporate trust office of the Warrant Agent.  In the event that
upon any exercise of Warrants evidenced hereby the number of Warrants exercised shall be less than the total number of Warrants
evidenced hereby, there shall be issued to the holder hereof or his, her or its assignee, a new Warrant Certificate evidencing
the number of Warrants not exercised.


 


Notwithstanding anything else in this Warrant
Certificate or the Warrant Agreement, no Warrant may be exercised unless at the time of exercise (i) a registration statement
covering the shares of Common Stock to be issued upon exercise is effective under the Securities Act and (ii) a prospectus
thereunder relating to the shares of Common Stock is current, except through “cashless exercise” as provided for in
the Warrant Agreement.


 


The Warrant Agreement provides that upon
the occurrence of certain events the number of shares of Common Stock issuable upon exercise of the Warrants set forth on the face
hereof may, subject to certain conditions, be adjusted.  If, upon exercise of a Warrant, the holder thereof would be entitled
to receive a fractional interest in a share of Common Stock, the Company shall, upon exercise, round down to the nearest whole
number of shares of Common Stock to be issued to the holder of the Warrant.


 


Warrant Certificates, when surrendered at
the principal corporate trust office of the Warrant Agent by the Registered Holder thereof in person or by legal representative
or attorney duly authorized in writing, may be exchanged, in the manner and subject to the limitations provided in the Warrant
Agreement, but without payment of any service charge, for another Warrant Certificate or Warrant Certificates of like tenor evidencing
in the aggregate a like number of Warrants.


 


Upon due presentation for registration of
transfer of this Warrant Certificate at the office of the Warrant Agent a new Warrant Certificate or Warrant Certificates of like
tenor and evidencing in the aggregate a like number of Warrants shall be issued to the transferee(s) in exchange for this
Warrant Certificate, subject to the limitations provided in the Warrant Agreement, without charge except for any tax or other governmental
charge imposed in connection therewith.


 


The Company and the Warrant Agent may deem
and treat the Registered Holder(s) hereof as the absolute owner(s) of this Warrant Certificate (notwithstanding any notation
of ownership or other writing hereon made by anyone), for the purpose of any exercise hereof, of any distribution to the holder(s) hereof,
and for all other purposes, and neither the Company nor the Warrant Agent shall be affected by any notice to the contrary. 
Neither the Warrants nor this Warrant Certificate entitles any holder hereof to any rights of a stockholder of the Company.


 






    	 	3	 



     


    

  





Election to Purchase


 


(To Be Executed Upon Exercise of Warrant)


 


The undersigned hereby irrevocably elects
to exercise the right, represented by this Warrant Certificate, to receive           
shares of Common Stock and herewith tenders payment for such shares of Common Stock to the order of Nebula Acquisition Corporation
(the “Company”) in the amount of $           in accordance
with the terms hereof.  The undersigned requests that a certificate for such shares of Common Stock be registered in the name
of      , whose address is            and that such
shares of Common Stock be delivered to                  
whose address is                .  If said number
of shares of Common Stock is less than all of the shares of Common Stock purchasable hereunder, the undersigned requests that a
new Warrant Certificate representing the remaining balance of such shares of Common Stock be registered in the name of                ,
whose address is                    and that such
Warrant Certificate be delivered to                ,
whose address is                .


 


In the event that the Warrant has been called
for redemption by the Company pursuant to Section 6 of the Warrant Agreement and the Company has required cashless
exercise pursuant to Section 6.3 of the Warrant Agreement, the number of shares of Common Stock that this Warrant is
exercisable for shall be determined in accordance with subsection 3.3.1(b) and Section 6.3 of the Warrant
Agreement.


 


In the event that the Warrant is a Private
Placement Warrant that is to be exercised on a “cashless” basis pursuant to subsection 3.3.1(c) of the
Warrant Agreement, the number of shares of Common Stock that this Warrant is exercisable for shall be determined in accordance
with subsection 3.3.1(c) of the Warrant Agreement.


 


In the event that the Warrant is to be exercised
on a “cashless” basis pursuant to Section 7.4 of the Warrant Agreement, the number of shares of Common
Stock that this Warrant is exercisable for shall be determined in accordance with Section 7.4 of the Warrant Agreement.


 


In the event that the Warrant may be exercised,
to the extent allowed by the Warrant Agreement, through cashless exercise (i) the number of shares of Common Stock that this
Warrant is exercisable for would be determined in accordance with the relevant section of the Warrant Agreement which allows for
such cashless exercise and (ii) the holder hereof shall complete the following: The undersigned hereby irrevocably elects
to exercise the right, represented by this Warrant Certificate, through the cashless exercise provisions of the Warrant Agreement,
to receive shares of Common Stock.  If said number of shares is less than all of the shares of Common Stock purchasable hereunder
(after giving effect to the cashless exercise), the undersigned requests that a new Warrant Certificate representing the remaining
balance of such shares of Common Stock be registered in the name of                ,
whose address is                    and that such
Warrant Certificate be delivered to                ,
whose address is                .


 


[Signature Page Follows]


 






    	 	4	 



     


    

 


	Date:                 , 20	 
	 	(Signature)
	 	 
	 	 
	 	 
	 	 
	 	(Address)
	 	 
	 	 
	 	(Tax Identification Number)


 


Signature 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 (OR ANY SUCCESSOR RULE)).


 






    	 	5