Exhibit 10.18


 


EXECUTION COPY


 


The Klein Group, LLC


640 Fifth Avenue


New York, NY 10019


 


CONFIDENTIAL


 


July 12, 2020


 


Churchill Capital Corp III


640 Fifth Avenue


New York, NY 10019


 


Ladies and Gentlemen:


 


This letter agreement (this “Agreement”)
confirms certain arrangements between Churchill Capital Corp III (the “Client”) and The Klein Group, LLC (“Advisor”)
with respect to the engagement of Advisor by the Client as its financial advisor to provide strategic advice and assistance to
the Client in connection with a Transaction (as defined below), including providing assistance in connection with the financing
of the Transaction. For purposes of this Agreement, “Transaction” means, whether effected directly or indirectly
or in one transaction or a series of transactions, the acquisition by the Client or any of its affiliates of all or a significant
portion of the business, assets or securities of, or any other effort by the Client to obtain control of, or a significant investment
in, Polaris Parent Corp. (together with its subsidiaries, “Target”), whether by way of a merger or consolidation,
reorganization, recapitalization or restructuring, tender or exchange offer, option, negotiated purchase, leveraged buyout, minority
investment or partnership, license, collaborative venture or otherwise, or any other extraordinary corporate transaction involving
the Client or any of its affiliates, on the one hand, and Target, on the other hand.


 


	1.	As consideration for the services to be rendered hereunder, the Client agrees to pay Advisor the
following cash fees:



 


		(a)	A transaction fee of $15 million, payable at or promptly following the closing of a Transaction.



 


		(b)	A placement fee of $15.5 million, payable at or promptly following the closing of a Transaction.



 


The fees pursuant to this Section
1 shall be payable in shares (based on $10 per share) of the Client, in an amount not to exceed $15 million, and the remainder
of such fees shall be payable in cash; provided that, in the event any advisors of the Client elect to be paid all or any
portion of their respective fees in shares (based on $10 per share) of the Client in lieu of cash, an amount of fees pursuant to
this Section 1 equal to such amount(s) may be payable to Advisor in cash in lieu of payment in shares of the Client pursuant to
this Section 1.


 






     


     


    

 


Churchill Capital Corp III


July 12, 2020


Page 2


 


In addition to such fees, the
Client will reimburse Advisor for Advisor’s reasonable, documented and customary out-of-pocket expenses (including reasonable
legal and other professional fees, expenses and disbursements) incurred in connection with the services to be provided by Advisor
hereunder, up to an amount not to exceed $50,000. Nothing contained herein shall be deemed to limit in any manner the indemnification,
expense reimbursement and other obligations of the Client under Annex A hereto.


 


		2.	In connection with the services to be provided hereunder, the Client will make available to Advisor
all information in the possession or control of the Client that is reasonably necessary for Advisor to provide the services hereunder.
The Client understands and confirms that (a) Advisor will use public reports and other information provided by others, including
information provided by the Client, other parties and their respective officers, employees, auditors, attorneys or other agents
in performing the services hereunder and (b) Advisor does not assume responsibility for, and may rely without independent verification
upon, the accuracy and completeness of any such information.



 


		3.	Advisor shall keep all information made available to Advisor by or on behalf of the Client
                                                               (the “Information”) confidential, except that nothing herein will prevent Advisor from disclosing the
                                                               Information to the extent that such Information (a) is disclosed with the Client’s prior written consent, (b) is
                                                               disclosed to Advisor’s affiliates or any of Advisor’s or any of its affiliate’s representatives, directors,
                                                               officers, employees, attorneys or agents (“Authorized Recipients”) in connection with the performance of
                                                               Advisor’s services hereunder; provided that (i) such Authorized Recipients have been advised to keep the
                                                               Information confidential in accordance with this Section 3 and (ii) Advisor shall be shall be responsible for any
                                                               breach of this Section 3 by an Authorized Recipient, or (c) is required to be disclosed by applicable law, regulation
                                                               or the order of a court of competent jurisdiction or is requested to be disclosed by a regulatory authority having
                                                               jurisdiction over Advisor or its representatives, provided, however, that prior to a disclosure pursuant to
                                                               clause (c), Advisor shall, to the extent legally permissible and reasonably practicable under the circumstances, provide
                                                               prior written notice to the Client of such disclosure requirement such that the Client may seek (at the Client’s sole
                                                               cost and expense) a protective order to avoid such disclosure or limit its scope or to obtain confidential treatment of that
                                                               portion of the Information legally required to be disclosed; provided, further that, Advisor shall use
                                                               commercially reasonable efforts to obtain reliable assurance that confidential treatment will be accorded any such
                                                               Information so disclosed. “Information” shall not include any information that (a) is or becomes generally
                                                               available to the public (other than as a result of disclosure by Advisor or any Authorized Recipient in breach of this
                                                               Agreement), (b) was available to Advisor or any Authorized Recipient on a non-confidential basis prior to its disclosure by
                                                               the Client or its affiliates or the other parties to a Transaction or (c) becomes available to Advisor or an Authorized
                                                               Recipient on a non-confidential basis from a person other than the Client or its affiliates or the other parties to a
                                                               Transaction, who is not to Advisor’s or such Authorized Recipient’s knowledge, bound by a duty of confidentiality
                                                               to the Client or its affiliates with respect to such information.



 






     


     


    

 


Churchill Capital Corp III


July 12, 2020


Page 3


 


		4.	The Client acknowledges that Advisor has been retained hereunder solely as an adviser to the Client,
and not as an adviser to or agent of any other person, and that Advisor’s engagement hereunder is as an independent contractor
and not in any other capacity including as a fiduciary. Any duties of Advisor arising out of its engagement pursuant to this Agreement
shall be owed solely to the Client. The Client agrees that any information or advice provided by Advisor in connection with Advisor’s
engagement hereunder is for the confidential use of the Client, and may not be provided to or relied upon by any other person without
Advisor’s prior written consent, other than to the Client’s affiliates. The Client will not use such information or
advice for any other purpose or disclose or otherwise refer to such information or advice, in any manner without Advisor’s
prior written consent. Neither Advisor’s engagement hereunder, nor the delivery of any advice in connection with Advisor’s
engagement hereunder, is intended to confer rights upon any persons not a party hereto (including security holders, employees,
directors or creditors of the Client) as against Advisor, its affiliates or any of their respective representatives, directors,
officers, employees or agents.



 


		5.	The Client acknowledges that it is not relying on the advice of Advisor for tax, legal, regulatory
or accounting matters, it is seeking and will rely on the advice of its own professionals and advisors for such matters and it
will make an independent analysis and decision regarding any Transaction or other matter based upon such advice. In addition, the
Client acknowledges that in no event shall Advisor act as an underwriter of any securities in connection with any Transaction.
Advisor may, to the extent it deems appropriate, render the services hereunder through one or more of its affiliates.



 


		6.	The Client agrees to indemnify Advisor in accordance with Annex A hereto, the terms of which
are incorporated into this Agreement in their entirety.



 


		7.	This Agreement will terminate upon the earlier of (a) the closing of the Transaction upon payment
of the fees set forth in Section 1 and (b) twelve (12) months after the date hereof. Upon the termination of this Agreement,
neither the Client nor Advisor shall have any liability or continuing obligation to the other party except for any fees accrued
and expenses incurred (subject to Section 1) by Advisor prior to the date of such expiration or termination; provided
that no such expiration or termination shall relieve any party from a breach of this Agreement occurring prior to such expiration
or termination. Notwithstanding the foregoing, Section 4, Section 6, this Section 7, Section 9, Section
10, Section 11 and Annex A hereto shall remain operative regardless of the expiration or termination of this
Agreement. It is also expressly agreed by the parties that, if a Transaction is consummated within twelve (12) months after the
expiration or termination of this Agreement or if a definitive agreement that results in consummation of a Transaction is entered
into during the term of this Agreement or within twelve (12) months after the expiration or termination of this Agreement, Advisor
shall be entitled to the applicable fees set forth herein.



 






     


     


    

 


Churchill Capital Corp III


July 12, 2020


Page 4


 


		8.	The Client understands and acknowledges that Advisor or its affiliates may currently hold, or in
the future may acquire, debt or equity securities (or other interests) issued by the Client or its affiliates, and will be under
no obligation to sell any such holdings in connection with this engagement. The Client is aware that Advisor and/or its affiliates
may currently or in the future (a) provide services to other parties with interests that conflict with the interests of the Client
or (b) engage in transactions (as a principal or otherwise) that conflict with the interests of the Client.



 


		9.	This Agreement (including Annex A) embodies the entire agreement and understanding between
the parties hereto and supersedes all prior agreements and understandings relating to the subject matter hereof. If any provision
of this Agreement is determined to be invalid or unenforceable in any respect, such determination will not affect the validity
or enforceability of any other provision of this Agreement, which will remain in full force and effect. No waiver, amendment or
other modification of this Agreement shall be effective unless in writing and signed by each party to be bound thereby. This Agreement
may not be assigned by the Client without Advisor’s prior written consent. This Agreement will be binding upon and inure
to the benefit of the Client, Advisor and their respective successors and permitted assigns. This Agreement may be executed in
counterparts, each of which shall be an original instrument and all of which taken together shall constitute one and the same agreement.



 


		10.	Advisor acknowledges that the Client established a trust account for the benefit of its public
shareholders upon the closing of its initial public offering and hereby irrevocably waives any and all right, title and interest,
or any claim of any kind arising out of this Agreement that it has or may have in the future, in or to any monies held in such
trust account, and agrees not to seek recourse against such trust account as a result of, or arising out of, this Agreement; provided,
that nothing herein shall serve to limit or prohibit the Target’s right to pursue a claim against the client or any of its
affiliates for legal relief against assets held outside the trust account (including from and after the consummation of a Transaction
other than as contemplated by this Agreement).



 






     


     


    

 


Churchill Capital Corp III


July 12, 2020


Page 5



 


		11.	This Agreement and any claim, counterclaim, proceeding or dispute of any kind or nature whatsoever,
directly or indirectly, arising out of or in any way relating to this Agreement or Advisor’s engagement hereunder (a “Claim”),
shall be governed and construed in accordance with the laws of the State of New York (without giving regard to any otherwise applicable
conflict of laws rules). No such Claim shall be commenced, prosecuted or continued in any forum other than the courts of the State
of New York located in the City and County of New York or in the United States District Court for the Southern District of New
York, which courts shall have exclusive jurisdiction over the adjudication of such matters, and each of the parties (on behalf
of itself and its respective successors and assigns) hereto hereby submits to the jurisdiction and venue of such courts (and any
appellate courts from any thereof) and personal service with respect thereto. Each of the parties hereto hereby waives on behalf
of itself and its successors and assigns any and all right to argue that the choice of forum provision is or has
become unreasonable in any legal proceeding. Each of the parties hereto hereby waives all right to trial by jury in any Claim (whether
based upon contract, tort or otherwise) directly or indirectly, arising out of or in any way relating to this Agreement or Advisor’s
engagement hereunder.



 


[Signature page follows]


 






     


     


    

 


Churchill Capital Corp III


July 12, 2020


Page 6


 


If the foregoing correctly sets forth our agreement, please
sign and return a copy of this Agreement.


 


	 	Very truly yours,
	 	 	 
	 	THE KLEIN GROUP, LLC
	 	 	 
	 	By:	 /s/ Jay
    Taragin
	 	Name:	   Jay Taragin
	 	Title:	Authorized Person



 


Accepted and agreed as of the date first written above:


 


	Churchill Capital Corp III  	 
	 	 	 
	By:	/s/ Michael Klein  	 
	Name:	Michael Klein  	 
	Title: 	Chief Executive Officer  	 




 


[Signature Page to Engagement Letter]


 






     


     


    

 



 


Churchill Capital Corp III


July 12, 2020


Page 7


 


Annex A


 


In connection with the engagement of Advisor
to render services to the Client pursuant to the Agreement to which this Annex A is attached, the Client and Advisor agree
and understand that in the event that Advisor, any of its affiliates or any of their respective representatives, directors, officers,
employees or agents (each of the foregoing, an “Indemnified Person”) become involved in any capacity in any
claim, suit, action, proceeding, arbitration or investigation (each an “Action”) brought or threatened by or
against any person related to, arising out of or in connection with Advisor’s engagement, Advisor’s performance of
any services in connection with the Agreement (whether before or after the date hereof) or any transaction contemplated thereby,
the Client will promptly reimburse each such Indemnified Person for its reasonable, documented and customary out-of-pocket expenses
(including reasonable legal fees of one counsel and other professional fees, expenses and disbursements) upon receipt of a written
request accompanied by reasonable supporting documentation. The Client will indemnify and hold harmless each Indemnified Person
from and against any actual losses, claims, damages, liabilities or expenses (collectively, “Losses”) to which
any Indemnified Person may become subject in connection with any pending or threatened Action related to, arising out of or in
connection with Advisor’s engagement pursuant to the Agreement, Advisor’s performance of any services in connection
therewith (whether before or after the date thereof) or any transaction contemplated thereby, whether or not in connection with
any Action in which the Client or an Indemnified Person is a party, except to the extent that any such Losses are found by a court
of competent jurisdiction in a final, non-appealable judgment to have resulted from such Indemnified Person’s fraud, gross
negligence, bad faith or willful misconduct. The Client also agrees that no Indemnified Person shall have any liability (whether
direct or indirect, in contract or tort or otherwise) to the Client, its security holders or creditors related to, arising out
of or in connection with Advisor’s engagement pursuant to the Agreement, Advisor’s performance of any services in connection
therewith (whether before or after the date thereof) or any transaction contemplated thereby, except to the extent that any Losses
are found by a court of competent jurisdiction in a final, non-appealable judgment to have resulted from such Indemnified Person’s
fraud, gross negligence, bad faith or willful misconduct; provided, however, that, in no event shall the Indemnified
Persons, in aggregate, be liable for or required to pay an amount in excess of the aggregate fees actually received by Advisor
for any services in connection Advisor’s engagement pursuant to the Agreement.


 


If for any reason the foregoing
indemnification is unavailable to an Indemnified Person or insufficient to hold such Indemnified Person harmless against
Losses (except to the extent not available under the terms of the preceding paragraph), then the Client shall contribute to
the Losses for which such indemnification is unavailable or insufficient in such proportion as is appropriate to reflect the
relative benefits received, or sought to be received, by the Client and its security holders, on the one hand, and the party
entitled to contribution, on the other hand, in the matters contemplated by Advisor’s engagement under the Agreement as
well as the relative fault of the Client and such party with respect to such Losses and any other relevant equitable
considerations. The Client agrees that, for the purposes hereof, the relative benefits received, or sought to be received, by
the Client (and its security holders) and Advisor shall be deemed to be in the same proportion as (a) the value to the Client
of the services and advice rendered by Advisor, bears to (b) the fees paid or payable to Advisor in connection with
Advisor’s engagement; provided, however, in no event shall Advisor or any other Indemnified Person be
required to contribute an aggregate amount in excess of the aggregate fees actually paid to Advisor in connection with
Advisor’s engagement pursuant to the Agreement, except in the case of fraud, gross negligence, bad faith or willful
misconduct of an Indemnified Person or breach by Advisor of its confidentiality obligations under paragraph 3 of the
Agreement. The Client and Advisor agree that it would not be just and equitable if contribution hereunder were determined by
pro rata allocation or by any other method that does not take into account the equitable considerations referred to
herein.


 



    


    


    

 


Churchill Capital Corp III


July 12, 2020


Page 8



 


If any Action shall be brought, threatened
or asserted against an Indemnified Person in respect of which indemnity may be sought against the Client, Advisor shall promptly
notify the Client in writing, and the Client shall be entitled, at its expense, and upon delivery of written notice to Advisor,
to assume the defense thereof with counsel reasonably satisfactory to Advisor. Such Indemnified Person shall have the right to
employ one separate counsel in any such Action and to participate in the defense thereof, but the fees and expenses of such counsel
shall be at the expense of such Indemnified Person unless (a) the Client has agreed in writing to pay such fees and expenses, (b)
the Client has failed to assume the defense in a timely manner or pursue the defense reasonably diligently or (c) outside counsel
to an Indemnified Person has advised such Indemnified Person that in such Action there is an actual conflict of interest or a conflict
on any material issue between the Client’s position and the position of such Indemnified Person, in which case the Client
shall be responsible for the fees and expenses of such separate counsel. It is understood, however, that in the situation in which
the Client shall be responsible for the fees and expenses of such counsel, the Client shall, in connection with any such Action
or separate but substantially similar or related Actions in the same jurisdiction arising out of substantially similar general
allegations or circumstances, be liable for the fees and expenses of only one counsel (in addition to local counsel) at any time
for all Indemnified Persons (unless in the reasonable belief of such Indemnified Persons based on the advice of outside counsel,
that there is an actual conflict of interest between of such Indemnified Persons, in which case such Indemnified Persons with conflicting
interests shall be represented by separate counsel and the Client shall be responsible for the fees and expenses of such counsel).


 


The Client agrees that, without Advisor’s
prior written consent (which shall not be unreasonably withheld, conditioned or delayed), it will not settle, compromise or consent
to the entry of any judgment in any pending or threatened Action in respect of which indemnification or contribution is reasonably
likely to be sought hereunder (whether or not Advisor or any other Indemnified Person is an actual or potential party to such
Action), unless such settlement, compromise or consent (a) includes an unconditional release from the settling, compromising or
consenting party of each Indemnified Person from all liability arising out of such Action, (b) shall not include a statement as
to, or an admission of, fault, culpability or a failure to act by or on behalf of any Indemnified Person, and (c) shall not impose
any monetary or financial obligations on any Indemnified Person.


 


The foregoing reimbursement, indemnity
and contribution obligations of the Client under this Annex A shall be in addition to any rights that an Indemnified Person
may have at common law or otherwise, and shall be binding upon and inure to the benefit of any successors, assigns, heirs and personal
representatives of the Client and such Indemnified Person. The provisions of this Annex A shall remain in full force and
effect regardless of any termination, modification or expiration of the Agreement. Without limiting any rights to indemnification,
exculpation or advancement of expenses of any indemnified person under the constitutive documents of the Client, the indemnification,
exculpation, limitation of liability and advancement of expense provisions apply to an Indemnified Person only in respect of the
services provided under the Agreement.