Specimen Warrant Certificate

Exhibit 4.3

SPECIMEN WARRANT CERTIFICATE

WARRANTS

THIS WARRANT SHALL BE NULL AND VOID IF NOT EXERCISED PRIOR TO THE

EXPIRATION OF THE EXERCISE PERIOD PROVIDED FOR

IN THE WARRANT AGREEMENT DESCRIBED BELOW

C5 ACQUISITION CORPORATION

Incorporated Under the Laws of the State of Delaware

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 C5 Acquisition Corporation, a Delaware corporation (the “Company”). Each whole 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 “Warrant Price”) as determined pursuant to the [Public][Private] Warrant Agreement, payable in lawful money of the United States of America upon surrender of this Warrant Certificate and payment of the Warrant Price (or through “cashless exercise” as provided for in the [Public][Private] Warrant Agreement) at the office or agency of the Warrant Agent referred to below, subject to the conditions set forth herein and in the [Public][Private] Warrant Agreement. Defined terms used in this Warrant Certificate but not defined herein shall have the meanings given to them in the [Public][Private] Warrant Agreement.

Each whole Warrant is initially exercisable for one fully paid and non-assessable share of Common Stock. No fractional shares will be issued upon exercise of any Warrant. If, upon the exercise of Warrants, a holder would be entitled to receive a fractional interest in a share of Common Stock, the Company will, upon exercise, round down to the nearest whole number of the number of shares of Common Stock to be issued to the holder of the Warrant. The number of shares of Common Stock issuable upon exercise of the Warrants is subject to adjustment upon the occurrence of certain events as set forth in the [Public][Private] Warrant Agreement.

The initial Warrant Price per share of Common Stock for any Warrant is equal to $11.50 per share. The Warrant Price is subject to adjustment upon the occurrence of certain events as set forth in the [Public][Private] 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 null and void. The Warrants may be redeemed, subject to certain conditions, as set forth in the [Public][Private] Warrant Agreement.

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 [Public][Private] Warrant Agreement.

This Warrant Certificate shall be governed by and construed in accordance with the internal laws of the State of New York.

[REVERSE OF WARRANT CERTIFICATE]

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 the [public][private] warrant agreement, dated as of [__], 2021 (as amended, supplemented or otherwise modified from time to time, the “Warrant Agreement”), by and between the Company to Continental Stock Transfer & Trust Company, a New York limited purpose trust company, as warrant agent (or successor warrant agent) (in such capacity, 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 Warrant Price as specified in the Warrant Agreement (or through “cashless exercise” as provided for in the Warrant Agreement) at the designated 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 (a)(i) a registration statement covering the issuance of 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 or (b) the shares of Common Stock to be issued upon exercise may be issued pursuant to an exemption from registration under the Securities Act, including 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 and the Warrant Price 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 designated 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 third party 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 and 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.

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 C5 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 shares of Common Stock be delivered to [        ] whose address is [        ].

In the event that the Warrant is to be exercised on a “cashless basis” pursuant to subsection 3.3.1(b) 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) 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.]¹

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 of Common Stock 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 shares of Common Stock be delivered to [        ] whose address is [        ].

[Signature Page Follows]

Date:                , 202[    ]