Exhibit 4.3


 


[Form of Warrant Certificate]


 


[Reverse]


 


The Warrants evidenced by this Warrant Certificate
are part of a duly authorized issue of Warrants entitling the holder on exercise to receive [               ]
Ordinary Shares and are issued or to be issued pursuant to a Warrant Agreement dated as of [●], 2020 (the “Warrant
Agreement”), duly executed and delivered by the Company to Continental Stock Transfer & Trust Company, a
New York corporation, 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, respectively) 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 issuance of the Ordinary Shares to be issued upon exercise is effective under the Securities Act and (ii) a prospectus
thereunder relating to the Ordinary Shares 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 Ordinary Shares 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 an Ordinary Share, the Company shall, upon exercise, round down to the nearest whole number of Ordinary
Shares 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 shareholder of the Company.


 






     


     


    

 


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 [               ]
Ordinary Shares and herewith tenders payment for such Ordinary Shares to the order of Horizon Acquisition Corporation (the “Company”)
in the amount of $[               ] in accordance with
the terms hereof. The undersigned requests that a certificate for such Ordinary Shares be registered in the name of [               ],
whose address is [               ] and that such Ordinary
Shares be delivered to [               ] whose address
is [               ]. If said [               ]
number of Ordinary Shares is less than all of the Ordinary Shares purchasable hereunder, the undersigned requests that a new Warrant
Certificate representing the remaining balance of such Ordinary Shares 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 6.2 of the Warrant Agreement and a holder thereof elects to exercise
its Warrant pursuant to a Make-Whole Exercise, the number of Ordinary Shares that this Warrant is exercisable for shall be determined
in accordance with subsection 3.3.1(c) or Section 6.2 of the Warrant Agreement, as applicable.


 


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 Ordinary Shares 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 Ordinary Shares 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 Ordinary Shares 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 Ordinary
Shares. If said number of shares is less than all of the Ordinary Shares purchasable hereunder (after giving effect to the cashless
exercise), the undersigned requests that a new Warrant Certificate representing the remaining balance of such Ordinary Shares be
registered in the name of [               ], whose address
is [               ] and that such Warrant Certificate
be delivered to [               ], whose address is
[               ].


 


[Signature Page Follows]


 






     


     


    

 


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 UNDER THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED).


 






     


     


    

 


EXHIBIT B


 


LEGEND


 


THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN
REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR ANY STATE SECURITIES LAWS, AND MAY NOT BE OFFERED, SOLD, TRANSFERRED
OR OTHERWISE DISPOSED OF UNLESS REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND ANY APPLICABLE STATE SECURITIES LAWS
OR AN EXEMPTION FROM REGISTRATION IS AVAILABLE. IN ADDITION, SUBJECT TO ANY ADDITIONAL LIMITATIONS ON TRANSFER DESCRIBED IN THE
LETTER AGREEMENT BY AND AMONG HORIZON ACQUISITION CORPORATION (THE “COMPANY”), HORIZON SPONSOR, LLC AND
THE OTHER PARTIES THERETO, THE SECURITIES REPRESENTED BY THIS CERTIFICATE MAY NOT BE SOLD OR TRANSFERRED PRIOR TO THE DATE
THAT IS THIRTY (30) DAYS AFTER THE DATE UPON WHICH THE COMPANY COMPLETES ITS INITIAL BUSINESS COMBINATION (AS DEFINED IN SECTION 3
OF THE WARRANT AGREEMENT REFERRED TO HEREIN) EXCEPT TO A PERMITTED TRANSFEREE (AS DEFINED IN SECTION 2 OF THE WARRANT AGREEMENT)
WHO AGREES IN WRITING WITH THE COMPANY TO BE SUBJECT TO SUCH TRANSFER PROVISIONS.


 


SECURITIES EVIDENCED BY THIS CERTIFICATE AND CLASS A ORDINARY
SHARES OF THE COMPANY ISSUED UPON EXERCISE OF SUCH SECURITIES SHALL BE ENTITLED TO REGISTRATION RIGHTS UNDER A REGISTRATION AND
SHAREHOLDER RIGHTS AGREEMENT TO BE EXECUTED BY THE COMPANY.


 


NO. [               ]
WARRANT