EX-10.5





 Exhibit 10.5 

PRIVATE PLACEMENT WARRANTS PURCHASE AGREEMENT 

This PRIVATE PLACEMENT WARRANTS PURCHASE AGREEMENT (this “Agreement”) is made as of the 21st day of October 2021, by and between M3-Brigade Acquisition III Corp., a Delaware corporation (the “Company”) and Cantor
Fitzgerald & Co. (the “Subscriber”). 
 WHEREAS, the Company desires to sell to the Subscriber on a private
placement basis (the “Offering”) an aggregate of 1,740,000 warrants (each, a “Placement Warrant” and, collectively, the “Placement Warrants”) of the Company, for a purchase price of $1.50 per
Placement Warrant. The shares of Common Stock underlying the Warrants are hereinafter referred to as the “Warrant Shares”. The Placement Warrants and Warrant Shares, collectively, are hereinafter referred to as the
“Securities.” Each whole Placement Warrant is exercisable to purchase one share of Common Stock at an exercise price of $11.50 commencing 30 days following the consummation of the Company’s initial business combination (the
“Business Combination”), as such term is defined in the registration statement in connection with the IPO, as amended at the time it becomes effective (the “Registration Statement”), and expiring on the fifth
anniversary of the consummation of the Business Combination (provided that so long as the Placement Warrants are held by the Subscriber or its designees, the Subscriber or its designees will not be permitted to exercise such Placement Warrants after
the five year anniversary of the effective date of the Registration Statement); and 
 WHEREAS, the Subscriber wishes to purchase an
aggregate of 1,740,000 Placement Warrants, and the Company wishes to accept such subscription from the Subscriber. 
 NOW, THEREFORE, in
consideration of the premises and the mutual covenants hereinafter set forth and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the Company and Subscriber hereby agree as follows: 

1. Agreement to Subscribe 

1.1. Purchase and Issuance of the Placement Warrants. Upon the terms and subject to the conditions of this Agreement, the Subscriber
hereby agrees to purchase from the Company, and the Company hereby agrees to sell to the Subscriber, on the Closing Date (as defined below) the Placement Warrants in consideration of the payment of the Purchase Price (as defined below). On the
Closing Date, the Company shall, at its option, deliver to the Subscriber the certificates representing the Placement Warrants purchased or effect such delivery in book-entry form. 

1.2. Purchase Price. As payment in full for the Placement Warrants being purchased under this Agreement, the Subscriber shall pay
$2,610,000.00 (the “Purchase Price”) by wire transfer of immediately available funds or by such other method as may be reasonably acceptable to the Company, to the trust account (the “Trust Account”) at a
financial institution to be chosen by the Company, maintained by Continental Stock Transfer & Trust Company, acting as trustee (“Continental”), on or prior to the Closing Date. 

1.3. Closing. The closing of the purchase and sale of the Placement Warrants shall take place simultaneously with the closing of the IPO (the
“Closing Date”). The closing of the purchase and sale of the Placement Warrants shall take place at the offices of Paul, Weiss, Rifkind, Wharton & Garrison LLP, 1285 Avenue of the Americas, New York, New York, 10019, or
such other place as may be agreed upon by the parties hereto. 
 1.4 Conditions to Closing. The obligation of the Subscriber to purchase and
pay for the Placement Warrants, as provided herein shall be subject to the satisfaction of the conditions set forth in Section 4 of the Underwriting Agreement, dated as of the date hereof, by and between the Company and the Subscriber, as
representative of the underwriters named therein (the “Underwriting Agreement”). 












 1.5 Termination. This Agreement and each of the obligations of the undersigned shall be null
and void and without effect if a Closing does not occur prior to December 31, 2021. 
 2. Representations and Warranties
of Subscriber 
 Subscriber represents and warrants to the Company that: 

2.1. No Government Recommendation or Approval. Subscriber understands that no federal or state agency has passed upon or made any
recommendation or endorsement of the Company or the Offering of the Securities. 
 2.2. Accredited Investor. Subscriber represents that it
is an “accredited investor” as such term is defined in Rule 501(a) of Regulation D under the Securities Act of 1933, as amended (the “Securities Act”), and acknowledges that the sale contemplated hereby is being made in
reliance, among other things, on a private placement exemption to “accredited investors” under the Securities Act and similar exemptions under state law. 

2.3. Intent. Subscriber is purchasing the Securities solely for investment purposes, for Subscriber’s own account (and/or for the account
or benefit of its members or affiliates, as permitted, pursuant to the terms hereof), and not with a view to the distribution thereof. 

2.4. Restrictions on Transfer. Subscriber acknowledges and understands the Placement Warrants are being offered in a transaction not involving
a public offering in the United States within the meaning of the Securities Act. The Securities have not been registered under the Securities Act and, if in the future Subscriber decides to offer, resell, pledge or otherwise transfer the Securities,
such Securities may be offered, resold, pledged or otherwise transferred only (A) pursuant to an effective registration statement filed under the Securities Act, (B) pursuant to an exemption from registration under Rule 144 promulgated
under the Securities Act, if available, or (C) pursuant to any other available exemption from the registration requirements of the Securities Act, and in each case in accordance with any applicable securities laws of any state or any other
jurisdiction. Notwithstanding the foregoing, Subscriber acknowledges and understands the Securities are subject to transfer restrictions as described in Section 8 hereof. Subscriber agrees that if any transfer of its Securities or any interest
therein is proposed to be made, as a condition precedent to any such transfer, Subscriber may be required to deliver to the Company an opinion of counsel satisfactory to the Company with respect to such transfer. Absent registration or another
available exemption from registration, Subscriber agrees it will not resell the Securities (unless otherwise permitted pursuant to the terms hereof). Subscriber further acknowledges that because the Company is a shell company, Rule 144 may not be
available to Subscriber for the resale of the Securities until the one year anniversary following consummation of the initial Business Combination of the Company, despite technical compliance with the requirements of Rule 144 and the release or
waiver of any contractual transfer restrictions. 
 2.5. Sophisticated Investor. 

(i) Subscriber is sophisticated in financial matters and is able to evaluate the risks and benefits of the investment in the Securities. 

(ii) Subscriber is aware that an investment in the Securities is highly speculative and subject to substantial risks because, among other
things, (a) the Securities are subject to transfer restrictions and have not been registered under the Securities Act and therefore cannot be sold unless subsequently registered under the Securities Act or an exemption from such registration is
available and (b) Subscriber has waived its redemption rights with respect to the Securities as set forth in Section 5 hereof, and the Securities held by the Subscriber are not entitled to, and have no right, interest or claim to any
monies held in the Trust Account, and accordingly Subscriber may suffer a loss of a portion or all of its investment in the Securities. Subscriber is able to bear the economic risk of its investment in the Securities for an indefinite period of
time. 
 2.6. Organization and Authority. Subscriber is duly organized, validly existing and in good standing under the laws of its state of
incorporation or formation and it possesses all requisite power and authority necessary to carry out the transactions contemplated by this Agreement. 












 2.7. Authority. This Agreement has been validly authorized, executed and delivered by
Subscriber and is a valid and binding agreement enforceable in accordance with its terms, subject to the general principles of equity and to bankruptcy or other laws affecting the enforcement of creditors’ rights generally. 

2.8. No Conflicts. The execution, delivery and performance of this Agreement and the consummation by Subscriber of the transactions
contemplated hereby do not violate, conflict with or constitute a default under (i) Subscriber’s charter documents, (ii) any agreement or instrument to which Subscriber is a party or (iii) any law, statute, rule or regulation to
which Subscriber is subject, or any agreement, order, judgment or decree to which Subscriber is subject. 
 2.9. No Legal Advice from
Company. Subscriber acknowledges it has had the opportunity to review this Agreement and the transactions contemplated by this Agreement and the other agreements entered into between the parties hereto with Subscriber’s own legal counsel and
investment and tax advisors. Except for any statements or representations of the Company made in this Agreement and the other agreements entered into between the parties hereto, Subscriber is relying solely on such counsel and advisors and not on
any statements or representations of the Company or any of its representatives or agents for legal, tax or investment advice with respect to this investment, the transactions contemplated by this Agreement or the securities laws of any jurisdiction.

 2.10. Reliance on Representations and Warranties. The Subscriber understands the Placement Warrants are being offered and sold to the
Subscriber in reliance on exemptions from the registration requirements under the Securities Act, and analogous provisions in the laws and regulations of various states, and that the Company is relying upon the truth and accuracy of the
representations, warranties, agreements, acknowledgments and understandings of the Subscriber set forth in this Agreement in order to determine the applicability of such provisions. 

2.11. No General Solicitation. Subscriber is not subscribing for the Placement Warrants as a result of or subsequent to any general
solicitation or general advertising, including but not limited to any advertisement, article, notice or other communication published in any newspaper, magazine, or similar media or broadcast over television or radio, or presented at any seminar or
meeting or in a registration statement with respect to the IPO filed with the Securities and Exchange Commission (“SEC”). 

2.12. Legend. Subscriber acknowledges and agrees the certificates evidencing each of the Securities shall bear a restrictive legend (the
“Legend”), in form and substance substantially as set forth in Section 4 hereof. 
 3. Representations,
Warranties and Covenants of the Company 
 The Company represents and warrants to, and agrees with, Subscriber that: 

3.1. Valid Issuance of Capital Stock. The total number of shares of all classes of capital stock which the Company has authority to issue is
550,000,000 shares of common stock (which consist of 500,000,000 shares of Class A Common Stock (the “Class A Common Stock”) and 50,000,000 shares of Class B Common Stock, $0.0001 par value per share (the
“Class B Common Stock”)), and 1,000,000 shares of preferred stock, $0.0001 par value per share (“Preferred Stock”). As of the date hereof, the Company has issued and outstanding no shares of
Class A Common Stock and 7,503,750 shares of Class B Common Stock (of which up to 978,750 shares are subject to forfeiture as described in the Registration Statement) and no shares of Preferred Stock. All of the issued shares of capital
stock of the Company have been duly authorized, validly issued, and are fully paid and non-assessable. 

3.2 Title to Securities. Upon issuance in accordance with, and payment pursuant to, the terms hereof and that certain private warrant
agreement to be entered into between the Company and Continental, as warrant agent (the “Private Warrant Agreement”), as the case may be, each of the Placement Warrants and Warrant Shares (after issuance) will be duly and
validly issued, fully paid and non-assessable. On the date of issuance of the Placement Warrants, Warrant Shares shall have been reserved for issuance. Upon issuance in accordance with, and payment pursuant
to, the terms hereof and the Private Warrant Agreement, as the case may be, Subscriber will have or receive good title to the Placement Warrants, free and clear of all liens, claims and encumbrances of any kind, other than (i) transfer
restrictions hereunder and (ii) transfer restrictions under federal and state securities laws. 












 3.3. Organization and Qualification. The Company is a corporation duly incorporated, validly
existing and in good standing under the laws of the State of Delaware and has the requisite corporate power to own its properties and assets and to carry on its business as now being conducted. 

3.4. Authorization; Enforcement. (i) The Company has the requisite corporate power and authority to enter into and perform its
obligations under this Agreement and to issue the Securities in accordance with the terms hereof, (ii) the execution, delivery and performance of this Agreement by the Company and the consummation by it of the transactions contemplated hereby
have been duly authorized by all necessary corporate action, and no further consent or authorization of the Company or its Board of Directors or stockholders is required, and (iii) this Agreement constitutes valid and binding obligations of the
Company enforceable against the Company in accordance with its terms, except as such enforceability may be limited by applicable bankruptcy, insolvency, fraudulent conveyance, moratorium, reorganization, or similar laws relating to, or affecting
generally the enforcement of, creditors’ rights and remedies or by equitable principles of general application and except as enforcement of rights to indemnity and contribution may be limited by federal and state securities laws or principles
of public policy. 
 3.5. No Conflicts. The execution, delivery and performance of this Agreement and the consummation by the Company of the
transactions contemplated hereby do not (i) result in a violation of the Company’s certificate of incorporation or by-laws, (ii) conflict with, or constitute a default under any agreement or
instrument to which the Company is a party or (iii) any law statute, rule or regulation to which the Company is subject or any agreement, order, judgment or decree to which the Company is subject. Other than any SEC or state securities filings
which may be required to be made by the Company subsequent to the Closing, and any registration statement which may be filed pursuant thereto, the Company is not required under federal, state or local law, rule or regulation to obtain any consent,
authorization or order of, or make any filing or registration with, any court or governmental agency or self-regulatory entity in order for it to perform any of its obligations under this Agreement or issue the Placement Warrants or Warrant Shares
in accordance with the terms hereof. 
 3.6. Additional Representations and Warranties. The representations and warranties of the Company
set forth in the Underwriting Agreement are hereby incorporated herein. 
 4. Legends 

4.1. Legend. The Company will issue the Placement Warrants, and when issued, the Warrant Shares, purchased by the Subscriber in the name of
the Subscriber. The Securities will bear the following Legend and appropriate “stop transfer” instructions: 

“THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE
“SECURITIES ACT”), OR ANY STATE SECURITIES LAWS, AND MAY NOT BE OFFERED, SOLD, TRANSFERRED OR OTHERWISE DISPOSED OF UNLESS REGISTERED UNDER THE SECURITIES ACT AND ANY APPLICABLE STATE SECURITIES LAWS OR AN EXEMPTION FROM REGISTRATION IS
AVAILABLE.” 
 “IN ADDITION, 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 M3-BRIGADE ACQUISITION III CORP. (THE “COMPANY”) COMPLETES ITS INITIAL BUSINESS COMBINATION (AS DEFINED IN SECTION 3 OF THE PRIVATE
WARRANT AGREEMENT REFERRED TO HEREIN) EXCEPT TO A PERMITTED TRANSFEREE (AS DEFINED IN SECTION 2 OF THE PRIVATE WARRANT AGREEMENT) WHO AGREES IN WRITING WITH THE COMPANY TO BE SUBJECT TO SUCH TRANSFER PROVISIONS.”

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












 4.2. Subscriber’s Compliance. Nothing in this Section 4 shall affect in any way
the Subscriber’s obligations and agreements to comply with all applicable securities laws upon resale of the Securities. 
 4.3.
Company’s Refusal to Register Transfer of the Securities. The Company shall refuse to register any transfer of the Securities, if in the sole judgment of the Company such purported transfer would not be made (i) pursuant to an effective
registration statement filed under the Securities Act, or pursuant to an available exemption from the registration requirements of the Securities Act and (ii) in compliance herewith. 

4.4 Registration Rights. The Subscriber will be entitled to certain registration rights which will be governed by a registration rights
agreement (“Registration Rights Agreement”) to be entered into between, among others, the Subscriber and the Company, on or prior to the effective date of the Registration Statement. Pursuant to the Registration Rights Agreement,
the Subscriber may not exercise its demand and “piggyback” registration rights after five (5) and seven (7) years after the effective date of the Registration Statement and may not exercise its demand rights on more than one
occasion. 
 5. Waiver of Liquidation Distributions. 

In connection with the Securities purchased pursuant to this Agreement, Subscriber hereby waives any and all right, title, interest or claim
of any kind in or to any distributions of the amounts in the Trust Account with respect to the Securities, whether (i) in connection with the exercise of redemption rights if the Company consummates the Business Combination, (ii) in
connection with any tender offer conducted by the Company prior to a Business Combination, (iii) upon the Company’s redemption of shares of Common Stock sold in the Company’s IPO upon the Company’s failure to timely complete the
Business Combination or (iv) in connection with a stockholder vote to approve an amendment to the Company’s amended and restated certificate of incorporation (A) to modify the substance or timing of the Company’s obligation to
redeem 100% of the Company’s public shares if the Company does not timely complete the Business Combination or (B) with respect to any other provision relating to stockholders’ rights or
pre-Business Combination activity. In the event Subscriber purchases shares of Common Stock in the IPO or in the aftermarket, any additional shares so purchased shall be eligible to receive the redemption
value of such shares of Common Stock upon the same terms offered to all other purchasers of Common Stock in the IPO in the event the Company fails to consummate the Business Combination. Nothing herein shall preclude Subscriber from making any claim
or seeking recourse against the Company’s funds held outside of the Trust Account or seeking to enforce the terms of the Underwriting Agreement. 

6. Terms of Placement Warrants. Each Placement Warrant shall have the terms set forth in the Private Warrant Agreement. 

7. Lock-Up Period. 

7.1. The Subscriber agrees that it shall not Transfer any Securities until 30 days following the consummation of the Business Combination;
provided, however, that Transfers of Securities are permitted (a) to the Company’s officers or directors, any affiliate or family member of any of the Company’s officers or directors or any affiliate of Subscriber or to any member(s)
of Subscriber or any of their affiliates; (b) in the case of an individual, by gift to a member of such individual’s immediate family or to a trust, the beneficiary of which is a member of such individual’s immediate family, an
affiliate of such individual or to a charitable organization; (c) in the case of an individual, by virtue of laws of descent and distribution upon death of such individual; (d) in the case of an individual, pursuant to a qualified domestic
relations order; (e) by private sales or transfers made in connection with any forward purchase agreement or similar arrangement or in connection with the consummation of the Business Combination at prices no greater than the price at which the
shares or warrants were originally purchased; (f) in the event of the Company’s liquidation prior to the completion of the Business Combination; (g) by virtue of the laws of the state of incorporation or formation of Subscriber or
Subscriber’s limited liability company agreement upon dissolution of Subscriber or (h) in the event of the Company’s liquidation, merger, capital stock exchange, reorganization or other similar transaction which results in all of the
Company’s stockholders having the right to exchange their shares of Common Stock for cash, securities or other property subsequent to the Business Combination; provided, however, that in the case of clauses (a) through (e) or (g), these
permitted transferees must enter into a written agreement with the Company agreeing to be bound by the Transfer restrictions herein. 












 7.2. For purposes of Section 7.1, the term “Transfer” shall mean the
(a) sale of, offer to sell, contract or agreement to sell, hypothecate, pledge, grant of any option to purchase or otherwise dispose of or agreement to dispose of, directly or indirectly, or establishment or increase of a put equivalent
position or liquidation with respect to or decrease of a call equivalent position within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, and the rules and regulations of the SEC promulgated thereunder with respect
to, any of the Securities, (b) entry into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of any of the Securities, whether any such transaction is to be settled by
delivery of such Securities, in cash or otherwise, or (c) public announcement of any intention to effect any transaction specified in clause (a) or (b). 

7.3 In addition to the restrictions on transfer described in Section 7.1, Subscriber acknowledges and agrees that the Placement Warrants
and their component parts and the related registration rights will be deemed compensation by the Financial Industry Regulatory Authority (“FINRA”) and will therefore, pursuant to Rule 5110(e) of the FINRA Manual, be subject to lock-up for a period of 180 days immediately following the commencement of sales in the IPO, subject to FINRA Rule 5110(e)(2). Additionally, the Placement Warrants and their component parts and the related
registration rights may not be sold, transferred, assigned, pledged or hypothecated during the foregoing 180 day period except to any underwriter or selected dealer participating in the IPO and the officers or partners, registered persons or
affiliates of any Subscriber and any such participating underwriter or selected dealer. Additionally, the Placement Warrants and their component parts and the related registration rights will not be the subject of any hedging, short sale,
derivative, put or call transaction that would result in the economic disposition of such securities by any person for a period of 180 days immediately following the commencement of sales in the IPO. 

8. Terms of the Placement Warrants 

The Placement Warrants are substantially identical to the warrants to be offered in the IPO except that: (i) the Placement Warrants are
subject to the transfer restrictions described in Section 7 hereof, (ii) the Placement Warrants will be non-redeemable so long as they are held by the initial holder thereof (or any of its permitted
transferees), and may be exercisable on a “cashless” basis, as further described in the Private Warrant Agreement, and (iii) the Placement Warrants are being purchased pursuant to an exemption from the registration requirements of the
Securities Act and will become freely tradable only after the expiration of the lockup described above in clause (i) and they are registered pursuant to the Registration Rights Agreement or an exemption from registration is available, and the
restrictions described above in clause (i) has expired. 
 9. Governing Law; Jurisdiction; Waiver of Jury Trial

 This Agreement shall be governed by and construed in accordance with the laws of the State of New York for agreements made and to be
wholly performed within such state. The parties hereto hereby waive any right to a jury trial in connection with any litigation pursuant to this Agreement and the transactions contemplated hereby. 

10. Assignment; Entire Agreement; Amendment 

10.1. Assignment. Neither this Agreement nor any rights hereunder may be assigned by any party to any other person other than by Subscriber to
a person agreeing to be bound by the terms hereof, including the transfer restrictions contained in Section 7 hereof. 
 10.2. Entire
Agreement. This Agreement sets forth the entire agreement and understanding between the parties as to the subject matter thereof and merges and supersedes all prior discussions, agreements and understandings of any and every nature among them. 

10.3. Amendment. Except as expressly provided in this Agreement, neither this Agreement nor any term hereof may be amended, waived, discharged
or terminated other than by a written instrument signed by all of the parties hereto. 
 10.4. Binding upon Successors. This Agreement shall
be binding upon and inure to the benefit of the parties hereto and to their respective heirs, legal representatives, successors and permitted assigns. 












 11. Notices 

11.1 Notices. Unless otherwise provided herein, any notice or other communication to a party hereunder shall be sufficiently given if in
writing and personally delivered or sent by facsimile or other electronic transmission with copy sent in another manner herein provided or sent by courier (which for all purposes of this Agreement shall include Federal Express or other recognized
overnight courier) or mailed to said party by certified mail, return receipt requested, at its address provided for herein or such other address as either may designate for itself in such notice to the other. Communications shall be deemed to have
been received when delivered personally, on the scheduled arrival date when sent by next day or 2nd-day courier service, or if sent by facsimile upon receipt of confirmation of transmittal or, if sent by mail,
then three days after deposit in the mail. If given by electronic transmission, such notice shall be deemed to be delivered (a) if by electronic mail, when directed to an electronic mail address at which the stockholder has consented to receive
notice; (b) if by a posting on an electronic network together with separate notice to the stockholder of such specific posting, upon the later of (1) such posting and (2) the giving of such separate notice; and (c) if by any
other form of electronic transmission, when directed to the stockholder. 
 12. Counterparts 

This Agreement may be executed in one or more counterparts, all of which when taken together shall be considered one and the same agreement
and shall become effective when counterparts have been signed by each party and delivered to the other party, it being understood that both parties need not sign the same counterpart. In the event that any signature is delivered by facsimile
transmission or by e-mail delivery of a “pdf” format data file, such signature shall create a valid and binding obligation of the party executing (or on whose behalf such signature is executed) with
the same force and effect as if such facsimile or “.pdf” signature page were an original thereof. 
 13. Survival;
Severability 
 13.1. Survival. The representations, warranties, covenants and agreements of the parties hereto shall survive the
Closing Date. 
 13.2. Severability. In the event that any provision of this Agreement becomes or is declared by a court of competent
jurisdiction to be illegal, unenforceable or void, this Agreement shall continue in full force and effect without said provision; provided that no such severability shall be effective if it materially changes the economic benefit of this Agreement
to any party. 
 14. Headings. 

The titles and subtitles used in this Agreement are used for convenience only and are not to be considered in construing or interpreting this
Agreement. 
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 IN WITNESS WHEREOF, the parties hereto have executed this Agreement to be effective as of
the date first set forth above. 
  
  

			
	COMPANY:
	
	M3-BRIGADE ACQUISITION III CORP.
		
	By:	 	/s/ Mohsin Meghji
		 	 Name: Mohsin Meghji

		 	 Title:Executive Chairman of the Board of Directors



  

			
	SUBSCRIBER:
	
	CANTOR FITZGERALD & CO.
		
	By:	 	/s/ Sage Kelly
		 	 Name: Sage Kelly

		 	 Title: