Document:

EX-4.3

 Exhibit 4.3 

Execution Version 

MONTROSE ENVIRONMENTAL GROUP, INC. 

THIRD AMENDED AND RESTATED 

VOTING AND DRAG ALONG AGREEMENT 

THIS THIRD AMENDED AND RESTATED VOTING AND DRAG ALONG AGREEMENT (the “Agreement”) is made as April 13, 2020 by and among
Montrose Environmental Group, Inc., a Delaware corporation (the “Company”), the holders of shares of Common Stock of the Company (the “Common Stock”) listed on Exhibit A, including the EW Transferees
(collectively, the “Common Stockholders” and individually a “Common Stockholder”), the holders of shares of the Company’s Cumulative Series A-1 Preferred Stock (the
“Series A-1 Preferred Stock”) and the Company’s Cumulative Series A-2 Preferred Stock (the “Series
A-2 Preferred Stock”) listed on Exhibit B (collectively, the “Preferred Stockholders,” individually a “Preferred Stockholder”), the warrantholders listed on
Exhibit C (the “Warrantholders” and jointly with the Common Stockholders and the Preferred Stockholders, the “Stockholders” or individually, a “Stockholder”). 

RECITALS 
 WHEREAS, the Company,
the Common Stockholders, the holders of shares of Series A-1 Preferred Stock, certain Warrantholders and EnviroWorks, LLC, a Delaware limited liability company (“EnviroWorks”), previously
entered into a Second Amended and Restated Voting and Drag Along Agreement dated October 19, 2018 (the “Original Agreement”); 

WHEREAS, the Company previously consummated a private placement of 12,000 shares of Series A-1
Preferred Stock and a warrant to issue 534,420 shares of Common Stock on October, 19, 2019, and issued such shares and warrant to OCM Montrose Holdings, L.P., a Delaware limited partnership; 

WHEREAS, on December 6, 2019, EnviroWorks transferred all of the Common Stock held by EnviroWorks to its members: (i) Richard E.
Perlman, (ii) Equity Trust Company, Custodian FBO Richard E. Perlman Roth IRA 2151260, (iii) Neal J. Fink, as Trustee of the Richard E. Perlman Irrevocable Trust F/B/O Wife’s Nieces and Nephews, U/A dated June 28, 2016, (iv) Neal J.
Fink, as Trustee of the Richard E. Perlman Grandchildren’s Irrevocable Trust, U/A dated June 28, 2016, (v) Neal J. Fink, as Trustee of the Richard E. Perlman Irrevocable Trust F/B/O Andrew Perlman, U/A dated June 28, 2016, (vi) James
K. Price, (vii) The Price Trust #1 FBO Kathleen Lauren Price, (viii) The Price Trust #2 FBO Nicole Ashley Price, (ix) The Price 2012 Trust and (x) J. Miguel Fernandez de Castro (collectively, the “EW Transferees”
and each an “EW Transferee”); 
 WHEREAS, the Company purchased on the date hereof all of the membership interests (the
“Acquisition”) of The Center for Toxicology and Environmental Health, L.L.C. pursuant to that certain Membership Interest Purchase Agreement, dated as of March 28, 2020, by and among the Company, Montrose Planning &
Permitting, LLC, Target, CTEH Holdings, LLC (“CTEH Holdings”) and certain other parties thereto in exchange for cash, 791,139 shares of Common Stock, which were issued to CTEH Holdings, and other contingent consideration; 

 WHEREAS, in connection with the Acquisition, pursuant to the terms of that certain Purchase
Agreement, dated as of March 28, 2020, by and between OCM Montrose II Holdings, L.P. and the Company, the Company has consummated a private placement (the “Offering”) of its new Series A-2
Preferred Stock and warrants to purchase Common Stock (the “Warrants”), the proceeds of which were used to partially fund the Acquisition; 

WHEREAS, in connection with the closing of the Offering, the Company, the Common Stockholders, the Warrantholders, and the Preferred
Stockholders desire to amend and restate the Original Agreement to, among other things, (i) add CTEH Holdings, the EW Transferees, and the Preferred Stockholders that were issued Series A-2 Preferred
Stock and the Warrantholders that were issued Warrants in the Offering, to the Original Agreement and (ii) incorporate the terms and conditions contemplated by the Offering, including the right of the holders of the Series A-2 Preferred Stock to appoint the Series A-2 Preferred Director (as defined below); and 

WHEREAS, this amended and restated Agreement requires the consent of the Company and EnviroWorks, the Preferred Stockholders and the
Warrantholders, which consent is evidenced by their execution of this Agreement. 
 AGREEMENT 

NOW, THEREFORE, in consideration of the mutual promises and covenants hereafter set forth, the parties hereby agree as follows: 

1. BOARD REPRESENTATION At each annual meeting of the stockholders of the Company, or at any meeting of the stockholders of the
Company at which members of the Board of Directors of the Company (the “Board”) are to be elected, or whenever members of the Board are to be elected by written consent, the Stockholders agree to vote or act with respect to their
shares so as to elect no fewer than seven (7) directors as follows: 
 (a) Three (3) individuals shall be designated jointly by
Richard E. Perlman and James K. Price (the “Investor Deciders”), who shall initially be Richard E. Perlman, James K. Price and J. Miguel Fernandez de Castro (each an “Investor Director”). 

(b) The Chief Executive Officer of the Company shall be designated a director for so long as he or she is employed by the Company. 

(c) So long as shares of Series A-1 Preferred Stock remain outstanding, one (1) or more
individuals (each a “Series A-1 Preferred Director”) shall be designated by the Holder Majority (as defined in the Amended and Restated Certificate of Designation of Cumulative Series A-1 Preferred Stock of the Company (the “Series A-1 Certificate” and such Holder Majority, the “Series A-1
Holder Majority”)) in accordance with the terms set forth in Section 4(c) of the Series A-1 Certificate, who shall initially be Brook Hinchman. 

(d) So long as shares of Series A-2 Preferred Stock remain outstanding, one (1) or more
individuals (each a “Series A-2 Preferred Director”) shall be designated by the Holder Majority (as defined in the Certificate of Designation of Cumulative Series A-2 Preferred Stock of the Company (the “Series A-2 Certificate”) and such Holder Majority, the “Series A-2
Holder Majority”)) in accordance with the terms set forth in Section 4(c) of the Series A-2 Certificate, who shall initially be Peter Jonna. 

  
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 (e) All remaining vacancies shall be designated by the Common Stockholders holding a
majority of the outstanding shares of Common Stock. The undersigned Common Stockholders agree to vote to elect Peter Graham, J. Thomas Presby and Robin Newmark to the Board through the earlier to occur of (i) twelve (12) months from the date
hereof or (ii) the filing or submission of a registration statement in connection with an initial public offering by the Company, after which time Messrs. Graham and Presby and Dr. Newmark may continue to serve on the Board if so elected
by a majority of the Common Stockholders. 
 2. CHANGE IN NUMBER OF DIRECTORS. Any increase or decrease in the number of
members of the Board shall occur in accordance with the terms and conditions set forth in the Company’s bylaws, the Series A-1 Certificate and the Series A-2
Certificate. Any vacancy on the Board shall be filled by the person or group that is entitled to designate the relevant director, if any, or otherwise as provided in the Company’s bylaws. The Company, the Investor Deciders and the Stockholders
shall take, at any time and from time to time, all actions necessary to effect the provisions of Section 1 and Section 2. 

3. DRAG-ALONG RIGHT 
 (a)
Definitions. 
 (i) A “Person” shall mean an individual, firm, a corporation, a partnership, an
association, a trust or unincorporated organization, limited liability company or any other entity or organization 
 (ii)
“Sale of the Company” shall mean any transaction or series of related transactions (by stock sale, merger, consolidation or otherwise) (a) consummated after the date hereof, pursuant to which a person acquires at least 51% of
the outstanding Voting Stock of the Company (including pursuant to a transfer or series of related transfers); or (b) that result in a sale or disposition of all or substantially all of the assets of the Company and its subsidiaries on a
consolidated basis other than to an entity with respect to which, following such sale or disposition, at least 50% of the combined voting power of the then outstanding Voting Stock of such entity is then beneficially owned (within the meaning of
Rule 13d-5 of the Securities and Exchange Act of 1934, as amended (the “Exchange Act”) as in effect on the date hereof), directly or indirectly, by all or substantially all of the individuals
and entities (or affiliates of such individuals and entities) who beneficially owned (within the meaning of Rule 13d-3 of the Exchange Act as in effect on the date hereof) the Voting Stock of the Company
immediately prior to such sale or other disposition. 
 (iii) “Voting Stock” as of any date means the
capital stock of the Company that is at the time entitled to vote in the election of the board of directors (or individuals performing similar functions) of the Company. 

  
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 (b) Actions to be Taken. In the event that the Investor Deciders approve a Sale of
the Company in writing, specifying that this Section 3 shall apply to such transaction, then each Stockholder hereby agrees: 

(i) if such transaction requires stockholder approval, with respect to all shares of Common Stock, Series A-1 Preferred Stock or Series A-2 Preferred Stock (the “Shares”) that such Stockholder owns or over which such Stockholder otherwise exercises voting power,
to the extent applicable, to vote (in person, by proxy or by action by written consent, as applicable) all Shares in favor of, and adopt, such Sale of the Company and to vote in opposition to any and all other proposals that could reasonably be
expected to delay or impair the ability of the Company to consummate such Sale of the Company; provided, that the foregoing shall not require the Warrantholders to so vote their Shares if such vote would, in such Warrantholder’s reasonable and
good faith discretion, cause the board of directors, general partner, manager or equivalent body of such Warrantholder to violate its fiduciary duties; 

(ii) if such transaction is a sale of stock, to sell the same proportion of shares of capital stock of the Company beneficially
held by such Stockholder as is being sold by the Investor Deciders to the Person to whom the Investor Deciders propose to sell their Shares 

(iii) to execute and deliver all related documentation in materially similar form as executed by the Investor Deciders and take
such other action in support of the Sale of the Company as shall reasonably be requested by the Company or the Investor Deciders in order to carry out the terms and provision of this Section 3, including without limitation
executing and delivering instruments of conveyance and transfer, and any purchase agreement, merger agreement, indemnity agreement, escrow agreement, consent (except, in the case of Warrantholders, for any consent that would, in such
Warrantholder’s reasonable and good faith discretion, cause the board of directors, general partner, manager or equivalent body of such Warrantholder to violate its fiduciary duties), waiver, governmental filing, share certificates duly
endorsed for transfer (free and clear of impermissible liens, claims and encumbrances) and any similar or related documents; provided, to the extent that the Stockholders are required to provide any indemnification with respect to breaches of
representations and warranties by or on behalf of the Company or agreements by the Company or otherwise assume any other post-closing liabilities, each Stockholder (other than the Preferred Stockholders) shall do so severally and not jointly (and on
a pro rata basis in accordance with the proceeds to be received by such Stockholder; provided, further, the only representations and warranties that a Stockholder shall be required to make in connection with such sale transaction are
with respect to his, her or its ownership of the Shares to be sold by him, her or it (which shall only include his, her or its ability to convey title free and clear of all liens, encumbrances, adverse claims or similar restrictions; no conflicts
with agreements to which, he, she or it is a party; no conflicts with law; authority; and enforceability) and no Stockholder shall be liable (on a pro rata basis or otherwise) for breach of the representations and warranties of any other Stockholder
made in its individual capacity as to its individual ownership, authorization and other related matters which apply only to such Stockholder; provided further that each Stockholder’s respective potential liability thereunder
(including any tax liability) shall not exceed the actual proceeds received by such Stockholder; and 

  
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 (iv) to refrain from exercising any dissenters’ rights or rights of
appraisal under applicable law at any time with respect to such Sale of the Company. 
 Notwithstanding the foregoing, in no event shall the
Preferred Stockholders or the Warrantholders be required to agree to any non-compete or non-solicitation covenants in connection with any sale under this
Section 3. In the event a sale under this Section 3 provides for consideration in a form other than cash, then the Company shall structure such sale so that the Warrantholders receive only cash in
such sale. 
 4. VOTING 

(a) Appointment of Directors. In the event of the resignation, death, removal or disqualification of a director selected under
Section 1, a new director shall promptly be nominated following the procedure originally used to designate the director being replaced and, after written notice of the nomination has been given by the Company to the
Stockholders following the director’s nomination, each Stockholder shall vote his, her or its shares of capital stock of the Company to elect such nominee to the Board. 

(b) Removal. A director elected under Section 1 may be removed at any time and from time to time, with or
without cause (subject to the Bylaws of the Company, the Series A-1 Certificate and the Series A-2 Certificate, as each are in effect from time to time and any
requirements of applicable law) in the following manner: in the case of a director nominated under Section 1(a), by the Investor Deciders; in the case of a director nominated under Section 1(c), by
the Series A-1 Holder Majority in accordance with the Series A-1 Certificate; in the case of a director nominated under Section 1(d), by the
Series A-2 Holder Majority in accordance with the Series A-2 Certificate; and in the case of a director nominated under Section 1(e), by
Stockholders holding a majority of the outstanding shares of Common Stock. 
 (c) Covenant to Vote. Each Stockholder or its
representative shall appear in person or by proxy at any annual or special meeting of stockholders for the purpose of obtaining a quorum and shall vote the shares of the Company’s capital stock owned by such Stockholder and entitled to vote
upon any matter submitted to a vote of the stockholders of the Company in a manner so as to be consistent and not in conflict with, and to implement, the terms of this Agreement. Each Stockholder shall execute any and all written consents circulated
with regard to any matter reasonably necessary to implement the terms of this Agreement and shall deliver each such executed consent to the Company without unreasonable delay. 

(d) Failure to Vote; Proxy Grant. In the event that any Stockholder shall fail to vote the shares it is entitled or required to vote in
the manner set forth herein, such Stockholder shall be deemed immediately upon the existence of such breach to have granted to the Chief Executive Officer, any Investor Director and each of them, with full power of substitution, as the proxies of
the party with respect to the matters set forth herein, and hereby authorizes each of them to represent and vote such Stockholder’s shares to ensure that such shares will be voted as set forth herein. Each of the Stockholders acknowledges that
each proxy granted hereby, including any successive proxy if need be, is given to secure the performance of a duty, is coupled with an interest, and shall be irrevocable until the duty is performed. Each party hereto hereby revokes any and all
previous proxies with respect to the shares of the Company’s capital stock. 

  
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 (e) No Voting or Conflicting Agreements. No Stockholder shall grant any proxy or
enter into or agree to be bound by any voting trust with respect to the shares held by such Stockholder nor shall any Stockholder enter into any stockholder agreements or arrangements of any kind with any person with respect to their shares
inconsistent with the provisions of this Agreement (whether or not such agreements and arrangements are with other stockholders of the Company that are not parties to this Agreement) unless, in connection with the Sale of the Company, specifically
requested to do so by the acquiror. The foregoing prohibition includes, but is not limited to, agreements or arrangements with respect to the acquisition, disposition or voting of shares of Common Stock held by such Stockholders , unless the
acquiror or transferee of such shares agrees to be bound by the terms of this Agreement with respect to the voting of such shares. No Stockholder shall act, for any reason, as a member of a group or in concert with any other persons in connection
with the acquisition, disposition or voting of shares of the Company’s capital stock in any manner which is inconsistent with the provisions of this Agreement. 

(f) Injunctive Relief. It is acknowledged that it will be impossible to measure in money the damages that would be suffered if the
parties fail to comply with any of the obligations herein imposed on them and that in the event of any such failure, an aggrieved person will be irreparably damaged and will not have an adequate remedy at law. Any such person shall, therefore, be
entitled to injunctive relief, including specific performance, to enforce such obligations, and if any action shall be brought in equity to enforce any of the provisions of this Agreement, none of the parties hereto shall raise the defense that
there is an adequate remedy at law. 
 5. LEGENDS. Each certificate representing any Stockholders’ shares shall be
endorsed by the Company with a legend reading as follows: 
 “THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”) AND MAY NOT BE TRANSFERRED, SOLD OR OTHERWISE DISPOSED OF EXCEPT WHILE A REGISTRATION STATEMENT RELATING THERETO IS IN EFFECT UNDER THE SECURITIES ACT OR PURSUANT
TO AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT. 
 THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO THE
DESIGNATIONS, RIGHTS, PREFERENCES, POWERS, RESTRICTIONS AND LIMITATIONS SET FORTH IN THE CERTIFICATE OF DESIGNATION FOR THE SERIES A-1 PREFERRED STOCK FILED WITH THE SECRETARY OF STATE FOR THE STATE OF
DELAWARE PURSUANT TO SECTION 151 OF THE DELAWARE GENERAL CORPORATION LAW (THE “A-1 CERTIFICATE OF DESIGNATION”) AND THE CERTIFICATE OF DESIGNATION FOR THE SERIES
A-2 PREFERRED STOCK FILED WITH THE SECRETARY OF STATE FOR THE STATE OF 

  
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DELAWARE PURSUANT TO SECTION 151 OF THE DELAWARE GENERAL CORPORATION LAW (THE “A-2 CERTIFICATE OF DESIGNATION”) AND THE RIGHTS, TERMS AND
CONDITIONS SET FORTH IN THE INVESTORS’ RIGHTS AGREEMENT, VOTING AND DRAG ALONG AGREEMENT AND RIGHT OF FIRST REFUSAL AND CO-SALE AGREEMENT, EACH BY AND AMONG MONTROSE ENVIRONMENTAL GROUP, INC. (THE
“ISSUER”) AND CERTAIN HOLDERS OF ISSUER SECURITIES PARTY THERETO (THE “INVESTMENT AGREEMENTS”). NO TRANSFER, SALE, ASSIGNMENT, PLEDGE, HYPOTHECATION OR OTHER DISPOSITION OF THE SECURITIES REPRESENTED BY THIS
CERTIFICATE MAY BE MADE EXCEPT IN ACCORDANCE WITH THE PROVISIONS OF THE A-1 CERTIFICATE OF DESIGNATION, THE A-2 CERTIFICATE OF DESIGNATION AND THE INVESTMENT AGREEMENTS.
A COPY OF THE CERTIFICATE OF DESIGNATION AND THE INVESTMENT AGREEMENTS WILL BE FURNISHED WITHOUT CHARGE BY THE ISSUER TO THE HOLDER UPON REQUEST.” 

6. NO LIABILITY FOR ELECTION OF RECOMMENDED DIRECTORS. Neither the Company, the Stockholders, nor any officer, director,
stockholder, partner, employee or agent of any such party, makes any representation or warranty as to the fitness or competence of the nominee of any party hereunder to serve on the Company’s Board by virtue of such party’s execution of
this Agreement or by the act of such party in voting for such nominee pursuant to this Agreement. 
 7. TERMINATION.
This Agreement shall terminate upon the earlier of (a) the closing of an initial public offering approved by the Investor Directors; (b) the closing of a Sale of the Company or (c) ten (10) years from the date hereof. A Stockholder
and/or Warrantholder, as applicable, shall cease to be deemed a Stockholder and/or Warrantholder hereunder, and shall no longer be a party to this Agreement, at such time as such Stockholder or Warrantholder ceases to own any securities of the
Company. 
 8. AMENDMENT; WAIVERS. Any provision of this Agreement may be amended or waived (either generally or in a
particular instance and either retroactively or prospectively) with the written consent of the Company; provided, however that any amendment to this Agreement in a manner that adversely affects the rights of the Investor Deciders,
Preferred Stockholders or the Warrantholders shall also require the written consent of the Investor Deciders (with respect to the Investor Deciders) holders of a majority in interest of the issued and outstanding shares of Preferred Stock or a
majority in interest of the shares of Common Stock underlying issued and outstanding warrants held by the Warrantholders, as applicable. Any amendment or waiver effected in accordance with this paragraph shall be binding upon the parties hereto but
in no event shall any amendment or waiver adversely affect the obligations or rights of any individual Stockholder or class or category of Stockholder in a manner different than the other Stockholders, except upon the written consent of such
Stockholder or a majority of such adversely affected class or category of Stockholders, as applicable. In addition, the Company may waive performance of any obligation owing to it, as to some or all of the Stockholders, or agree to accept
alternatives to such performance, without obtaining the consent of any Stockholder so long as such waiver or acceptance of alternative performance affects all Stockholders equally. The Company may amend Exhibits A, B, C and
D hereto, without obtaining the approval of any of the Stockholders, Warrantholders or Investor Deciders, to reflect any changes to the information set forth thereon resulting from the issuance of any new securities or transfer of any
securities, in each case, provided such issuance or transfer was in accordance with the terms of this Agreement. 

  
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 9. NOTICES. All notices, demands or other communications hereunder
shall be in writing and shall be deemed given when delivered personally, mailed by certified mail, return receipt requested, sent by overnight courier service or telecopied, telegraphed or telexed (transmission confirmed), or otherwise actually
delivered to the party to be notified at such party’s address as set forth below or on the signature pages hereto, or as subsequently modified by written notice. 

10. SEVERABILITY. If one or more provisions of this Agreement are held to be unenforceable under applicable law, the
parties agree to renegotiate such provision in good faith. In the event that the parties cannot reach a mutually agreeable and enforceable replacement for such provision, then (a) such provision shall be excluded from this Agreement;
(b) the balance of the Agreement shall be interpreted as if such provision were so excluded; and (c) the balance of the Agreement shall be enforceable in accordance with its terms. 

11. GOVERNING LAW; CONSENT TO JURISDICTION; WAIVER OF JURY TRIAL. This Agreement and all acts and
transactions pursuant hereto and the rights and obligations of the parties hereto shall be governed, construed and interpreted in accordance with the laws of the State of Delaware, without giving effect to principles of conflicts of law. The parties
hereto hereby consent to the jurisdiction of any state or federal court located within the area encompassed by the State of Delaware and irrevocably agree that all actions or proceedings arising out of or relating to this Agreement shall be
litigated in such courts. Each party hereto accepts for itself and in connection with its respective properties, generally and unconditionally, the exclusive jurisdiction and venue of the aforesaid courts and waives any defense of forum non
conveniens, and irrevocably agrees to be bound by any final, nonappealable judgment rendered thereby in connection with this Agreement. TO THE EXTENT NOT PROHIBITED BY APPLICABLE LAW WHICH CANNOT BE WAIVED, EACH PARTY HERETO HEREBY WAIVES AND
COVENANTS THAT IT WILL NOT ASSERT (WHETHER AS PLAINTIFF, DEFENDANT OR OTHERWISE) ANY RIGHT TO TRIAL BY JURY IN ANY FORUM IN RESPECT OF ANY ISSUE OR ACTION, CLAIM, CAUSE OF ACTION OR SUIT (IN CONTRACT, TORT OR OTHERWISE), INQUIRY, PROCEEDING OR
INVESTIGATION ARISING OUT OF OR BASED UPON THIS AGREEMENT OR THE SUBJECT MATTER HEREOF OR IN ANY WAY CONNECTED WITH OR RELATED OR INCIDENTAL TO THE TRANSACTIONS CONTEMPLATED HEREBY, IN EACH CASE WHETHER NOW EXISTING OR HEREAFTER ARISING. EACH PARTY
HERETO ACKNOWLEDGES THAT IT HAS BEEN INFORMED BY THE OTHER PARTIES HERETO THAT THIS SECTION 11 CONSTITUTES A MATERIAL INDUCEMENT UPON WHICH THEY ARE RELYING AND WILL RELY IN ENTERING INTO THIS AGREEMENT. ANY PARTY HERETO MAY FILE AN ORIGINAL
COUNTERPART OR A COPY OF THIS SECTION 11 WITH ANY COURT AS WRITTEN EVIDENCE OF THE CONSENT OF EACH SUCH PARTY TO THE WAIVER OF ITS RIGHT TO TRIAL BY JURY. 

  
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 12. ENTIRE AGREEMENT. This Agreement constitutes the entire
understanding and agreement of the parties with respect to the subject matter hereof and supersedes all prior negotiations, correspondence, agreements (including the Original Agreement), understandings, duties or obligations among the parties with
respect to the subject matter hereof. 
 13. COUNTERPARTS. This Agreement may be executed in two or more counterparts,
each of which shall be deemed an original and all of which together shall constitute one instrument. The exchange of copies of this Agreement and of signature pages by facsimile transmission (whether directly from one facsimile device to another by
means of a dial-up connection or whether mediated by the worldwide web), by electronic mail in “portable document format” (“.pdf”) form, or by any other electronic means intended to
preserve the original graphic and pictorial appearance of a document, or by combination of such means, shall constitute effective execution and delivery of this Agreement as to the parties and may be used in lieu of the original Agreement for all
purposes. Signatures of the parties transmitted by facsimile shall be deemed to be their original signatures for all purposes. 
 14.
SUCCESSORS AND ASSIGNS. The terms and conditions of this Agreement shall inure to the benefit of and be binding upon the respective successors and assigns of the parties. Nothing in this Agreement, express or implied, is intended
to confer upon any party other than the parties hereto or their respective successors and assigns any rights, remedies, obligations, or liabilities under or by reason of this Agreement, except as expressly provided in this Agreement. 

15. ADDITIONAL STOCKHOLDERS. Notwithstanding Section 8 above, in the event that after the date
of this Agreement, the Company issues shares of capital stock to any Person (including, but not limited to, shares issued to Warrantholders following the exercise of warrants to purchase capital stock of the Company), the Company shall cause such
Person to execute a Joinder Agreement in the form attached hereto as Exhibit D, and such party shall thereby be bound by, and subject to, all the terms and provisions of this Agreement applicable to a Stockholder. 

[REMAINDER OF THIS PAGE INTENTIONALLY LEFT BLANK] 

  
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 IN WITNESS WHEREOF, the parties hereto have executed this Third Amended and Restated Voting
and Drag Along Agreement as of the date first written above. 
  

							
	COMPANY:	 		 	ADDRESS:
			
	MONTROSE ENVIRONMENTAL GROUP, INC.	 		 	
				
	By:	 	 /s/ Vijay Manthripragada
	 		 	1 Park Plaza
		 	Name: Vijay Manthripragada	 		 	Suite 1000
		 	Title: Chief Executive Officer	 		 	Irvine, CA 92614

 [SIGNATURE PAGE TO MONTROSE ENVIRONMENTAL GROUP, INC. 

THIRD AMENDED AND RESTATED VOTING AND DRAG ALONG AGREEMENT] 

 IN WITNESS WHEREOF, the parties hereto have executed this Third Amended and Restated Voting
and Drag Along Agreement as of the date first written above. 
  

							
	COMMON STOCKHOLDERS:	 	ADDRESS:
		
	Richard E. Perlman	 	
		
	 /s/ Richard E. Perlman

Richard E. Perlman
	 	
		
	Equity Trust Company, Custodian FBO	 	
	Richard E. Perlman Roth IRA 2151260	 	
				
	By:	 	 /s/ Richard E. Perlman
	 	  
	 	
	Name:	 	Richard E. Perlman	 		 	
	Title:	 		 		 	
		
	Neal J. Fink, as Trustee of the Richard E. Perlman	 	
	Irrevocable Trust F/B/O Wife’s Nieces and	 	
	Nephews, U/A dated June 28, 2016	 	
				
	By:	 	 /s/ Neil J. Fink
	 	  
	 	
	Name:	 	Neil J. Fink	 		 	
	Title:	 	Trustee	 		 	
		
	Neal J. Fink, as Trustee of the Richard E. Perlman	 	
	Grandchildren’s Irrevocable Trust, U/A dated June 28, 2016	 	
				
	By:	 	 /s/ Neil J. Fink
	 	  
	 	
	Name:	 	Neil J. Fink	 		 	
	Title:	 	Trustee	 		 	

 [SIGNATURE PAGE TO MONTROSE ENVIRONMENTAL GROUP, INC. 

THIRD AMENDED AND RESTATED VOTING AND DRAG ALONG AGREEMENT] 

			
	Neal J. Fink, as Trustee of the Richard E. Perlman
	Irrevocable Trust F/B/O Andrew Perlman, U/A dated June 28, 2016
		
	By:	 	 /s/ Neil J. Fink

	Name:	 	Neil J. Fink
	Title:	 	Trustee
	
	James K. Price
	
	 ?s/ James K. Price

James K. Price

	
	The Price Trust #1 FBO Kathleen Lauren Price
		
	By:	 	 /s/ WK Price IV

	Name:	 	WK Price IV
	Title:	 	Trustee
	
	The Price Trust #2 FBO Nicole Ashley Price
		
	By:	 	 /s/ WK Price IV

	Name:	 	WK Price IV
	Title:	 	Trustee
	
	The Price 2012 Trust
		
	By:	 	 /s/ WK Price IV

	Name:	 	WK Price IV
	Title:	 	Trustee
	
	J. Miguel Fernandez de Castro
	
	 /s/ J. Miguel Fernandez de Castro

J. Miguel Fernandez de Castro

  
 12 

			
	CTEH Holdings, LLC
		
	By:	 	 /s/ Phillip T. Goad

	Name:	 	Phillip T. Goad
	Title:	 	CEO

  
 13 

 IN WITNESS WHEREOF, the parties hereto have executed this Third Amended and Restated Voting
and Drag Along Agreement as of the date first written above. 
  

							
	PREFERRED STOCKHOLDERS:	 		 	ADDRESS:
		 		 		 	 c/o Oaktree Capital Management, L.P.
 333 S.
Grand Ave., 28th Floor

		 		 		 	Los Angeles, CA 90071
			
	OCM Montrose Holdings, L.P.	 		 	
				
	By:	 	Oaktree Fund GP, LLC	 		 	
	Its:	 	General Partner	 		 	
				
	By:	 	Oaktree Fund GP I, L.P.	 		 	
	Its:	 	Managing Member	 		 	
				
	By:	 	 /s/ Brook Hinchman
	 		 	
	Name:	 	Brook Hinchman	 		 	
	Title:	 	Authorized Signatory	 		 	
				
	By:	 	 /s/ Jordan Mikes
	 		 	
	Name:	 	Jordan Mikes	 		 	
	Title:	 	Authorized Signatory	 		 	
			
	OCM Montrose II Holdings, L.P.	 		 	
				
	By:	 	Oaktree Fund GP, LLC	 		 	
	Its:	 	General Partner	 		 	
				
	By:	 	Oaktree Fund GP I, L.P.	 		 	
	Its:	 	Managing Member	 		 	
				
	By:	 	 /s/ Brook Hinchman
	 		 	
	Name:	 	Brook Hinchman	 		 	
	Title:	 	Authorized Signatory	 		 	
				
	By:	 	 /s/ Jordan Mikes
	 		 	
	Name:	 	Jordan Mikes	 		 	
	Title:	 	Authorized Signatory	 		 	

 [SIGNATURE PAGE TO MONTROSE ENVIRONMENTAL GROUP, INC. 

THIRD AMENDED AND RESTATED VOTING AND DRAG ALONG AGREEMENT] 

 IN WITNESS WHEREOF, the parties hereto have executed this Third Amended and Restated Voting
and Drag Along Agreement as of the date first written above. 
  

							
	WARRANTHOLDERS:	 		 	ADDRESS:
		 		 		 	 c/o Oaktree Capital Management, L.P.
 333 S.
Grand Ave., 28th Floor

		 		 		 	Los Angeles, CA 90071
			
	OCM Montrose Holdings, L.P.	 		 	
				
	By:	 	Oaktree Fund GP, LLC	 		 	
	Its:	 	General Partner	 		 	
				
	By:	 	Oaktree Fund GP I, L.P.	 		 	
	Its:	 	Managing Member	 		 	
				
	By:	 	 /s/ Brook Hinchman
	 		 	
	Name:	 	Brook Hinchman	 		 	
	Title:	 	Authorized Signatory	 		 	
				
	By:	 	 /s/ Jordan Mikes
	 		 	
	Name:	 	Jordan Mikes	 		 	
	Title:	 	Authorized Signatory	 		 	
			
	OCM Montrose II Holdings, L.P.	 		 	
				
	By:	 	Oaktree Fund GP, LLC	 		 	
	Its:	 	General Partner	 		 	
				
	By:	 	Oaktree Fund GP I, L.P.	 		 	
	Its:	 	Managing Member	 		 	
				
	By:	 	 /s/ Brook Hinchman
	 		 	
	Name:	 	Brook Hinchman	 		 	
	Title:	 	Authorized Signatory	 		 	
				
	By:	 	 /s/ Jordan Mikes
	 		 	
	Name:	 	Jordan Mikes	 		 	
	Title:	 	Authorized Signatory	 		 	

 [SIGNATURE PAGE TO MONTROSE ENVIRONMENTAL GROUP, INC. 

THIRD AMENDED AND RESTATED VOTING AND DRAG ALONG AGREEMENT] 

 EXHIBIT B 

SCHEDULE OF PREFERRED STOCKHOLDERS 
 OCM
Montrose Holdings, L.P. 
 OCM Montrose II Holdings, L.P. 

 EXHIBIT C 

SCHEDULE OF WARRANTHOLDERS 
 OCM Montrose
Holdings, L.P. 
 OCM Montrose II Holdings, L.P. 

 EXHIBIT D 

JOINDER AGREEMENT TO 

MONTROSE ENVIRONMENTAL GROUP, INC. 

THIRD AMENDED AND RESTATED VOTING AND DRAG ALONG AGREEMENT 

The undersigned hereby agrees, effective as of the date hereof, to become a party to that certain Third Amended and Restated Voting and Drag
Along Agreement (the “Agreement”) dated as of April 13, 2020, as may be amended from time to time, by and among Montrose Environmental Group, Inc., a Delaware corporation (the “Company”) and the other parties from
time to time parties named therein, to become bound by all of the terms and conditions of the Agreement as though an original party thereto and shall assume all applicable rights and obligations of a [Stockholder/Warrantholder], as defined in the
Agreement. The address, electronic mail address and facsimile number to which notices shall be sent to the undersigned are as follows: 
  

					
	Address:	 	              
	  	
			
		 	  
	  	
			
		 	  
	  	
			
		 	  
	  	
		
	Facsimile Number:
                                         
                                         
 	  	
		
	Email:
                                         
                                         
                     	  	

 Accordingly, the undersigned has executed and delivered this Joinder Agreement as of the date written below.

  

	
	  

	Print Name:
                                         
                        
	Date:EX-4.5

 EXHIBIT 4.5 

EXECUTION VERSION 
 THIS WARRANT AND ANY
SECURITIES ACQUIRED UPON EXERCISE OF THIS WARRANT HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR ANY STATE SECURITIES LAWS, AND NONE OF THIS WARRANT, SUCH SECURITIES OR ANY INTEREST THEREIN MAY BE OFFERED, SOLD,
TRANSFERRED, PLEDGED OR OTHERWISE DISPOSED OF EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER SUCH ACT OR SUCH LAWS OR AN EXEMPTION FROM REGISTRATION UNDER SUCH ACT AND SUCH LAWS. 

THIS WARRANT AND THE SECURITIES ACQUIRED UPON EXERCISE OF THIS WARRANT ARE SUBJECT TO THE RIGHTS, TERMS AND CONDITIONS SPECIFIED BELOW AND IN THE STOCKHOLDER
AGREEMENTS, IN EACH CASE AS AMENDED FROM TIME TO TIME. NO TRANSFER, SALE, ASSIGNMENT, PLEDGE, HYPOTHECATION OR OTHER DISPOSITION OF THIS WARRANT MAY BE MADE EXCEPT IN ACCORDANCE WITH THE PROVISIONS OF THE STOCKHOLDER AGREEMENTS. A COPY OF THE
STOCKHOLDER AGREEMENTS WILL BE FURNISHED WITHOUT CHARGE BY THE COMPANY TO THE HOLDER UPON REQUEST. 
 MONTROSE ENVIRONMENTAL GROUP, INC.

 WARRANT 
  

			
	 Issuance Date: October 19, 2018
	  	Certificate No. W-            

 FOR VALUE RECEIVED, Montrose Environmental Group, Inc., a Delaware corporation (the
“Company”), hereby grants to OCM Montrose Holdings, L.P., a Delaware limited partnership or its registered assigns (the “Registered Holder”) the right, upon the terms and subject to the conditions set forth herein,
to purchase from the Company 534,240 shares of the Warrant Stock at a price per share of $0.01 (as adjusted from time to time in accordance herewith, the “Exercise Price”); provided that the Registered Holder may exercise this
Warrant on a “net” basis by paying the Aggregate Exercise Price (as defined below) by delivering to the Company a portion of this Warrant with a Fair Market Value equal to such Aggregate Exercise Price as set forth in Section 1B(ii).
In connection with this grant, the Registered Holder, the Company and the holders of Common Stock will enter into each of the Stockholder Agreements. Certain capitalized terms used herein are defined in Section 4 hereof.
The amount and kind of securities obtainable pursuant to the rights granted hereunder and the purchase price for such securities are subject to adjustment pursuant to the provisions contained in this Warrant. 

 This Warrant is subject to the following provisions: 

Section 1.    Exercise of Warrant. 

1A.    Exercise Period. The Registered Holder or the Purchaser (as defined below) may exercise, in whole or in
part, the purchase rights for the Warrant Stock represented by this Warrant at any time and from time to time after the Issuance Date to and including the Expiration Date (the “Exercise Period”). 

1B.    Exercise Procedure. 

(i)    This Warrant shall be deemed to have been exercised when the Company has received all of the following items (the
“Exercise Time”): 
 (a)    a completed Exercise Agreement, as described in
Section 1C (the “Exercise Agreement”), duly executed by the Person exercising all or part of the purchase rights represented by this Warrant (the “Purchaser”); 

(b)    this Warrant; 

(c)    if this Warrant is not registered in the name of the Purchaser, an assignment or assignments
substantially in the form set forth on Exhibit I attached hereto evidencing the assignment of this Warrant to the Purchaser, in which case the Registered Holder shall have complied with the provisions set forth in
Section 6; 
 (d)    a check or wire transfer of immediately available funds
payable to the Company in an amount equal to the product of the Exercise Price multiplied by the number of shares of Warrant Stock being purchased upon such exercise (the “Aggregate Exercise Price”); and 

(e)    a Joinder Agreement to each of the Stockholder Agreements in the form attached to the applicable
Stockholder Agreement, in each case duly executed by the Purchaser pursuant to and in accordance with the applicable Stockholder Agreement. 

(ii)    As an alternative to the exercise of this Warrant as provided in Section 1B(i), the
holder of this Warrant may exercise this Warrant on a “net basis” such that in lieu of payment of the Aggregate Exercise Price, the number of shares of the Warrant Stock issuable upon exercise of this Warrant shall be reduced by a number
of shares of the Warrant Stock with a Fair Market Value equal to the Aggregate Exercise Price. 
 (iii)    Certificates
for shares of Warrant Stock purchased upon exercise of this Warrant shall be delivered by the Company to the Purchaser within five business days after the date of the Exercise Time. Unless this Warrant has expired or all of the rights represented
hereby have been exercised, the Company shall prepare a new Warrant, substantially identical hereto, representing the rights formerly represented by this Warrant which have not expired or been exercised and shall, within such five-business day
period, deliver such new Warrant to the Person designated for delivery in the Exercise Agreement. 

 (iv)    No fractional shares or scrip representing fractional shares
shall be issued upon an exercise of this Warrant. In lieu of any fraction shares which would otherwise be issuable, the Company shall pay cash equal to the product of such fraction multiplied by the fair market value of one share of Warrant Stock at
the Exercise Time. The “fair market value” shall be determined in good faith by the Board of Directors of the Company. 

(v)    The issuance of certificates for shares of Warrant Stock upon exercise of this Warrant shall be made without charge
to the Registered Holder or the Purchaser for any stamp duty or similar tax with respect to such issuance. Each share of Warrant Stock will, upon exercise of this Warrant in accordance with the terms hereof and payment of the Exercise Price
therefor, be fully paid and nonassessable and free from all liens with respect to the issuance thereof. 
 (vi)    The
Warrant Stock issuable upon the exercise of this Warrant shall be deemed to have been issued to the Purchaser at the Exercise Time, and the Purchaser shall be deemed for all purposes to have become the record holder of such Warrant Stock at the
Exercise Time. 
 (vii)    The Company shall not close its books against the transfer of this Warrant or of any share of
Warrant Stock issued or issuable upon the exercise of this Warrant in any manner which interferes with the timely exercise of this Warrant. The Company shall from time to time take all such action as may be necessary to assure that the par value per
share of the unissued Warrant Stock acquirable upon exercise of this Warrant is at all times equal to or less than the Exercise Price then in effect. 

(viii)    The Company shall use commercially reasonable efforts to assist and cooperate with any Registered Holder or
Purchaser required to make any governmental filings or obtain any governmental approvals prior to or in connection with any exercise of this Warrant (including, without limitation, making any filings required to be made by the Company). Any such
governmental filings or approvals required prior to or in connection with the exercise of this Warrant shall be made or obtained at the Registered Holder’s expense. 

(ix)    The Company shall give the Registered Holder at least 20 days’ advance written notice of the date on which a
Sale of the Company (as defined in the Investors Rights Agreement) or an IPO would become effective (“Transaction Notice”). Notwithstanding any other provision hereof, if an exercise of any portion of this Warrant is to be made in
connection with an IPO or the Sale of the Company, the exercise of any portion of this Warrant may, at the election of the Registered Holder or Purchaser, be conditioned upon the consummation of the IPO or Sale of the Company in which case such
exercise shall not be deemed to be effective until the consummation of such transaction. 
 (x)    The Company shall at
all times reserve and keep available out of its authorized but unissued shares of Warrant Stock solely for the purpose of issuance upon the exercise of this Warrant, such number of shares of Warrant Stock issuable upon the exercise of this Warrant
(and any other warrants issued by the Company). All shares of Warrant Stock which are so issuable shall, when issued, be duly and validly issued. The Company shall take commercially reasonable steps to assure that all such shares of Warrant Stock
may be so issued without violation of any applicable law or governmental regulation or any requirements of any 

 
domestic securities exchange upon which shares of Common Stock may be listed (except for official notice of issuance which shall be immediately delivered by the Company upon each such issuance).
The Company shall not take any action which would cause the number of authorized but unissued shares of Common Stock to be less than the number of shares of the Warrant Stock required to be reserved hereunder for issuance upon exercise of this
Warrant (and any other warrants issued by the Company). 
 (xi)    Upon request by the Registered Holder from time to
time, but not more than one time per quarter, the Company shall issue to the Registered Holder a certificate setting forth the then-outstanding Common Stock or other equity interests of the Company and any securities convertible into or exchangeable
for Common Stock or other equity interests of the Company. 
 1C.    Exercise Agreement. Upon any exercise of
this Warrant, the Exercise Agreement shall be substantially in the form set forth on Exhibit II attached hereto, except that if the shares of Warrant Stock are not to be issued in the name of the Person in whose name this Warrant is
registered, the Exercise Agreement shall also state the name of the Person to whom the certificates for the shares of Warrant Stock are to be issued, and if the number of shares of Warrant Stock to be issued does not include all the shares of
Warrant Stock purchasable hereunder, the Exercise Agreement shall also state the name of the Person to whom a new Warrant for the unexercised portion of the rights hereunder is to be delivered. Such Exercise Agreement shall be dated the actual date
of execution thereof and shall indicate whether the Aggregate Exercise Price is to be paid in cash or on a “net basis”. 

Section 2.    Record Date. If the Company takes a record of the holders of Common Stock for the purpose of
entitling them (i) to receive a dividend or other distribution payable in Common Stock, Options or in Convertible Securities or (ii) to subscribe for or purchase Common Stock, Options or Convertible Securities, then such record date shall
be deemed to be the date of the issue or sale of the shares of Common Stock deemed to have been issued or sold upon the declaration of such dividend or the making of such other distribution or the date of the granting of such right of subscription
or purchase, as the case may be. 
 2A.    Subdivision or Combination of Common Stock. If the Company at any time
subdivides (by any stock split, stock dividend, recapitalization or otherwise) the Warrant Stock into a greater number of shares, the Exercise Price in effect immediately prior to such subdivision shall be proportionately reduced and the number of
shares of Warrant Stock obtainable upon exercise of this Warrant shall be proportionately increased. If the Company at any time combines (by reverse stock split or otherwise) the Warrant Stock into a smaller number of shares, the Exercise Price in
effect immediately prior to such combination shall be proportionately increased and the number of shares of Warrant Stock obtainable upon exercise of this Warrant shall be proportionately decreased. In addition, the number of shares of Common Stock
outstanding at any given time does not include shares owned or held by or for the account of the Company or any subsidiary thereof, and the disposition of any shares so owned or held shall be considered an issue or sale of Common Stock. 

2B.    Reorganization, Reclassification, Consolidation, Merger or Sale. Any recapitalization, reorganization,
reclassification, spin-off, consolidation, merger, sale of all or substantially all of the Company’s assets with, into or to another Person or other similar transaction

 
which is effected in such a way that holders of Common Stock are entitled to receive (either directly or upon subsequent liquidation) stock or other equity interests, securities, assets or other
property with respect to or in exchange for Common Stock is referred to herein as “Organic Change”; provided that (1) in the event an Organic Change that is a Sale of the Company provides for consideration in a form other than
cash or (2) in connection with an Organic Change in which the Company is not the surviving Person and the Person surviving any such consolidation, merger or sale (if other than the Company) or to which such sale, assignment, transfer, lease,
conveyance or other disposition will have been made is not a corporation organized or existing under the laws of the jurisdiction of organization of the Company, or the laws of the United States, any state thereof or the District of Columbia, or any
territory thereof (a “Specified Corporation”), in each case the Company shall structure such Organic Change in a manner so that the Registered Holder receives only cash in such Organic Change (and, in case of clause (2), upon
receiving such cash, the Registered Holder shall not be adversely affected in respect of taxes as compared with the Organic Change occurring and the Registered Holder being paid in cash immediately prior to the Company becoming a Specified
Corporation (if applicable)). Prior to the consummation of any Organic Change, the Company shall make appropriate provision to ensure that the Registered Holder of this Warrant shall thereafter have the right to acquire and receive, in lieu of or in
addition to (as the case may be) the shares of Warrant Stock immediately theretofore acquirable and receivable upon the exercise of this Warrant, such shares of stock or equity interests, securities, assets or other property as would have been
issued or payable in such Organic Change (as if this Warrant had been exercised immediately prior to such Organic Change) with respect to or in exchange for the shares of Warrant Stock immediately theretofore acquirable and receivable upon exercise
of this Warrant had such Organic Change not taken place. In any such case, the Company shall make appropriate provision with respect to such holder’s rights and interests to ensure that the provisions of this Section 2
shall thereafter be applicable to this Warrant. The Company shall not effect any such consolidation, merger or sale, unless prior to the consummation thereof, the successor entity (if other than the Company) resulting from consolidation or merger or
the entity purchasing such assets assumes by written instrument, the obligation to deliver to each such holder such shares of stock or equity interests, securities, assets or other property as, in accordance with the foregoing provisions, such
holder may be entitled to acquire. The Company, its successor entity or the purchaser entity, as applicable, shall promptly issue to the Registered Holder a certificate setting forth the aggregate shares of the Common Stock or equity interests,
securities, assets or other property obtainable under this Warrant following such recapitalization, reorganization, reclassification, consolidation, merger or sale. 

2C.    Notices. 

(i)    Upon any adjustment of the Exercise Price and/or number of shares of Warrant Stock, the Company shall give written
notice thereof to the Registered Holder, setting forth in reasonable detail and certifying the calculation of such adjustment. 

(ii)    The Company shall give written notice to the Registered Holder at least 10 days prior to the date on which the
Company closes its books or takes a record (a) with respect to any dividend or distribution upon the Common Stock, (b) with respect to any pro rata subscription offer (including with respect to any options, convertible securities or rights
to purchase stock, warrants, securities or other property) to holders of Common Stock or (c) for determining rights to vote with respect to any Organic Change, Sale of the Company, IPO, dissolution or liquidation. 

 (iii)    The Company shall give written notice to the Registered Holder
at least 10 days prior to the date on which any Organic Change, Sale of the Company, IPO, dissolution or liquidation shall take place. 

2D.    No Impairment. The Company shall not avoid or seek to avoid the observance or performance of any of the
terms to be observed or performed by the Company under this Section 2, but shall at all times in good faith assist in carrying out of all the provisions of this Section 2 and in taking all such
reasonable action as may be necessary or appropriate to protect the Registered Holder’s rights under this Section 2 against impairment. 

2E.    Restricted Actions. For so long as the Registered Holder holds any portion of this Warrant, the Company
shall not, and shall cause its subsidiaries not to become subject to (including, without limitation, by way of amendment to or modification of) any agreement or instrument which by its terms would materially restrict the right of the Company or any
of its subsidiaries to fulfill its obligations under this Warrant. 
 2F.    Expenses. The Company shall prepare,
issue and deliver at its own expense any new Warrant or Warrants required to be issued hereunder. 

Section 3.    Dividends and Distributions. If the Company declares or pays a dividend or distribution upon its
Common Stock, except for a dividend or distribution payable in common stock (a “Distribution”), then the Company shall pay to the Registered Holder (or any Person designated by the Registered Holder) at the time of payment thereof
the Distribution which would have been paid to the Registered Holder on the Warrant Stock had this Warrant been fully exercised immediately prior to the date on which a record is taken for such Distribution or, if no record is taken, the date as of
which the record holders of Common Stock entitled to such Distribution are to be determined. 

Section 4.    Definitions. The following terms have meanings set forth below: 

“Commission” means the Securities and Exchange Commission. 

“Common Stock” means, the Company’s Common Stock, par value $0.000004, and any capital stock of any class of the Company
hereafter authorized which is not limited to a fixed sum or percentage of par or stated value in respect to the rights of the holders thereof to participate in dividends or in the distribution of assets upon any liquidation, dissolution or winding
up of the Company. 
 “Convertible Securities” means any stock or securities (directly or indirectly) convertible into or
exchangeable for Common Stock. 
 “Expiration Date” the date that is the 10th anniversary of the Issuance Date. 

“Fair Market Value” of the Company will mean the amount which the Company would receive in an
all-cash sale of all of its assets and businesses as a going concern (free and clear of all liens and after payment of indebtedness for borrowed money) in an arms-length transaction with an unaffiliated third
party consummated on the day immediately preceding the 

 
date on which the event occurred which necessitated the determination of the Fair Market Value. After a determination of the Fair Market Value of the Company is made as provided above, the Fair
Market Value of (i) an equity security will be determined by making a calculation reflecting the cash distributions which would be made to the equityholders in accordance with the Company’s certificate of incorporation in respect of such
equity security if the Company were deemed to have received such Fair Market Value in cash and then distributed the same to the equityholders in accordance with the terms of the Company’s certificate of incorporation incident to the liquidation
of the Company after payment to all of the Company’s creditors from such cash receipts, and assuming that all of the convertible debt and other convertible securities were repaid or converted (whichever yields more cash to the holders of such
convertible securities) and all options to acquire equity securities (whether or not currently exercisable) that have an exercise price below the Fair Market Value of such equity securities were exercised and the exercise price therefor paid, and
(ii) a warrant will be determined by reference to the Fair Market Value, if any, of the equity securities issuable thereunder, reduced by the aggregate exercise price applicable thereto. In the event of a Sale of the Company, the Fair Market
Value of an equity security shall be equal to the price paid for such equity security in such Sale of the Company, to the extent applicable. “Fair Market Value” shall be determined in good faith by the Board of Directors of the Company.

 “Investors Rights Agreement” means that certain Second Amended and Restated Investors’ Rights Agreement, dated on
or around the date hereof, by and among the Company and the stockholders and warrantholders party thereto. 
 “IPO” means
an initial sale of Common Stock of the Company or any subsidiary of the Company (or, in each case, any successor thereto) pursuant to an effective registration statement under the Securities Act filed with the Commission. 

“Options” means any rights or options to subscribe for or purchase Common Stock or Convertible Securities. 

“Person” means an individual, a partnership, a joint venture, a corporation, a limited liability company, a trust, an
unincorporated organization and a government or any department or agency thereof. 
 “Securities Act” means the Securities
Act of 1933, as amended, or any similar or successor federal statute and the rules and regulations of the Commission thereunder, all as the same shall be in effect at the time. 

“Stockholder Agreements” means the Investors Rights Agreement, that certain Second Amended and Restated Voting and Drag Along
Agreement, dated on or around the date hereof, by and among the Company and the stockholders and warrantholders party thereto and that certain Second Amended and Restated Right of First Refusal and Co-Sale
Agreement, dated on or around the date hereof, by and among the Company and the stockholders and warrantholders party thereto (the “ROFR and Co-Sale Agreement”). 

“Warrant Stock” means shares of the Common Stock; provided that if there is a change such that the securities issuable
upon exercise of the Warrants are issued by an entity other than the Company or there is a change in the type or class of securities so issuable, then the term 

 
“Warrant Stock” shall mean one share of the security issuable upon exercise of the Warrants if such security is issuable in shares, or shall mean the smallest unit in which such
security is issuable if such security is not issuable in shares. 
 Section 5.    No Rights as a Stockholder;
Limitations of Liability. This Warrant shall not entitle the holder hereof to any voting rights or other rights as a stockholder of the Company. No provision hereof, in the absence of affirmative action by the Registered Holder to purchase
Warrant Stock by exercise of this Warrant, and no enumeration herein of the rights or privileges of the Registered Holder shall (i) cause the Registered Holder to be or have any rights of a stockholder of the Company for any purpose or
(ii) give rise to any liability of such holder for the Exercise Price of Warrant Stock acquirable by exercise hereof or as a stockholder of the Company. 

Section 6.    Transfers. 

6A.    Unregistered Securities. Each holder of this Warrant acknowledges that this Warrant and the Warrant Stock
have not been registered under the Securities Act, and agrees not to sell, offer for sale, pledge, hypothecate, distribute, transfer or otherwise dispose of this Warrant or any Warrant Stock issued upon its exercise in violation of any of the
Stockholder Agreements. Each certificate or other instrument for Warrant Stock issued upon the exercise of this Warrant pursuant to Section 1B shall bear a legend substantially to the foregoing effect. 

6B.    Restrictions on Transfer. This Warrant and any securities acquired upon exercise of this Warrant may not be
transferred or assigned in whole or in part except in accordance with the terms and conditions set forth in the Stockholder Agreements, including the Permitted Transfers (as defined in the ROFR and Co-Sale
Agreement) of the Registered Holder. 
 Section 7.    Warrant Exchangeable for Different Denominations. This
Warrant is exchangeable, upon the surrender hereof by the Registered Holder at the principal office of the Company, for new Warrants of like tenor representing in the aggregate the rights hereunder, and each new Warrant shall represent such portion
of such rights as is designated by the Registered Holder at the time of such surrender. The date the Company initially issues this Warrant shall be deemed to be the “Issuance Date” hereof regardless of the number of times new
certificates representing the unexpired and unexercised rights formerly represented by this Warrant shall be issued. All Warrants representing portions of the rights hereunder are included in the definition of this “Warrant” hereunder.

 Section 8.    Replacement. Upon receipt of evidence reasonably satisfactory to the Company (an affidavit
of the Registered Holder shall be satisfactory) of the ownership and the loss, theft, destruction or mutilation of any certificate evidencing this Warrant, and in the case of any such loss, theft or destruction, upon receipt of indemnity reasonably
satisfactory to the Company, or, in the case of any such mutilation upon surrender of such certificate, the Company shall (at its expense) execute and deliver in lieu of such certificate a new certificate of like kind representing the same rights
represented by such lost, stolen, destroyed or mutilated certificate and dated the date of such lost, stolen, destroyed or mutilated certificate. 

 Section 9.    Notices. Except as expressly set forth to the
contrary in this Warrant, all notices, requests or consents provided for or permitted to be given under this Warrant must be in writing and shall be deemed delivered (a) one business day after depositing such writing with a reputable overnight
courier for next day delivery, (b) three business days after depositing such writing in the United States mail, postage paid, and registered or certified with return receipt requested or (c) upon delivering such writing to the recipient in
person, by courier or by facsimile or electronic transmission (if the facsimile or electronic mail is sent during normal business hours of the recipient; but if not, then such notice shall be deemed given on the next business day). All notices,
requests and consents to be sent to the Registered Holder must be sent to or made at c/o Oaktree Capital Management, L.P., 333 S. Grand Ave., 28th Fl., Los Angeles, CA 90071, Attention: Emily Stephens and Brook Hinchman, Facsimile: ***
and ***, Email: *** and ***, or such other address as the Registered Holder may specify by notice to the Company. Any notice, request or consent to the Company must be sent to or made at Montrose Environmental Group, Inc., 1 Park Plaza, Suite 1000,
Irvine, CA, 92614, Attention: Nasym Afsari, Facsimile: ***, Email: ***. 
 Section 10.    Severability.
Wherever possible, each provision of this Warrant shall be interpreted in such manner as to be effective and valid under applicable law, but if any provision of this Warrant shall be prohibited by or invalid under applicable law, such provision
shall be ineffective to the extent of such prohibition or invalidity, without invalidating the remainder of such provision or the remaining provisions of this Warrant. 

Section 11.    Amendment and Waiver. The provisions of this Warrant may be amended and the Company may take
any action herein prohibited, or omit to perform any act herein required to be performed by it, only with, in each case, the prior written consent of the Company and the Registered Holders of Warrants representing a majority of the Warrant Stock
obtainable upon exercise of the Warrants. 
 Section 12.    Descriptive Headings; Governing Law. The
descriptive headings of the several sections and paragraphs of this Warrant are inserted for convenience only and do not constitute a part of this Warrant. The corporate laws of the State of Delaware shall govern all issues concerning the relative
rights of the Company and its stockholders. All other issues concerning the construction, validity, enforcement and interpretation of this Warrant shall be governed by the internal law of the State of Delaware, without giving effect to any choice of
law or conflict of law provision or rule (whether of the State of Delaware or any other jurisdictions) that would cause the application of the laws of any jurisdictions other than the State of Delaware. 

*    *    *    * 

 IN WITNESS WHEREOF, the parties have executed this Warrant as of the Issuance Date hereof.

  

			
	MONTROSE ENVIRONMENTAL GROUP, INC.
	
	                                    
        

 
			
	By:	 	 /s/ Vijay Manthripragada

	Name:	 	Vijay Manthripragada
	Title:	 	Chief Executive Officer

 [SIGNATURE PAGE TO WARRANT] 

 Accepted and Agreed: 
  

			
	OCM Montrose Holdings, L.P.
		
	By:	 	Oaktree Fund GP, LLC
	Its:	 	General Partner
		
	By:	 	Oaktree Fund GP I, L.P.
	Its:	 	Managing Member
		
	By:	 	 /s/ Bob O’Leary

	Name:	 	Bob O’Leary
	Title:	 	Authorized Signatory
		
	By:	 	 /s/ Brook Hinchman

	Name:	 	Brook Hinchman
	Title:	 	Authorized Signatory

 [SIGNATURE PAGE TO WARRANT] 

 EXHIBIT I 

ASSIGNMENT 
 FOR VALUE RECEIVED,
                                         
                    the undersigned hereby sells, assigns and transfers all of the rights of the undersigned under the attached Warrant (Certificate
No. W-                ) with respect to the number of shares of the common stock of Montrose Environmental Group, Inc.
covered thereby set forth below, unto: 
  

					
	 Names of Assignee
	 	 Address
	 	 No. of Shares

		 		 	
		 		 	
		 		 	

 Each assignee listed above hereby acknowledges and agrees to be bound by all terms and conditions of the
attached Warrant as if such assignee were signatory to this Warrant. 
  

			
	[NAME OF HOLDER]

 
			
		
	By:	 	  

 
			
	Name:	 	
	Title:	 	

  

			
	Agreed and acknowledged by:
	
	[NAME OF ASSIGNEE]

			
		
	By:	 	  

			
	Name:	 	
	Title:	 	

  

			
	Date:	 	  

 EXHIBIT II 

EXERCISE AGREEMENT 
  

			
	 To: Montrose Environmental Group, Inc.
	  	 Dated:

 The undersigned, pursuant to the provisions set forth in the attached Warrant (Certificate No. W-            ), hereby agrees to subscribe for the purchase of
                 shares of the common stock of Montrose Environmental Group, Inc., a Delaware corporation, covered by such Warrant [and makes payment herewith in
full therefor at the price per unit provided by such Warrant] [and elects to effect such exercise on a “net basis”]. 
  

			
	[NAME OF HOLDER]

  

			
	By:	 	  

 
			
	Name:	 	
	Title:	 	
		
	Address:

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00311-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00311-of-00352.parquet"}]]