EX-10.2





 Exhibit 10.2 

Executed 

INVESTMENT MANAGEMENT TRUST AGREEMENT 

This Investment Management Trust Agreement (this “Agreement”) is made effective as of March 22, 2021 by and
between Supernova Partners Acquisition Company III, Ltd., a Cayman Islands exempted company (the “Company”), and American Stock Transfer & Trust Company, LLC (the “Trustee”). 

WHEREAS, the Company’s registration statement on Form S-1, File
No. 333-253235 (the “Registration Statement”) and prospectus (the “Prospectus”) for the initial public offering of the Company’s units (the
“Units”), each of which consists of one of the Company’s Class A ordinary shares, par value $0.0001 per share (the “Ordinary Shares”), and a fraction of one redeemable warrant, each whole
warrant entitling the holder thereof to purchase one Ordinary Share (such initial public offering hereinafter referred to as the “Offering”), has been declared effective as of the date hereof by the U.S. Securities and
Exchange Commission; and 
 WHEREAS, the Company has entered into an Underwriting Agreement (the “Underwriting
Agreement”) with J.P. Morgan Securities LLC and Jeffries LLC, as representatives (the “Representatives”) to the several underwriters (the “Underwriters”) named therein; and 

WHEREAS, as described in the Prospectus, $250,000,000 of the gross proceeds of the Offering and sale of the Private Placement Warrants (as
defined in the Underwriting Agreement) (or $287,500,000 if the Underwriters’ option to purchase additional units is exercised in full) will be delivered to the Trustee to be deposited and held in a segregated trust account located at all times
in the United States (the “Trust Account”) for the benefit of the Company and the holders of the Ordinary Shares included in the Units issued in the Offering as hereinafter provided (the amount to be delivered to the Trustee
(and any interest subsequently earned thereon) is referred to herein as the “Property,” the shareholders for whose benefit the Trustee shall hold the Property will be referred to as the “Public
Shareholders,” and the Public Shareholders and the Company will be referred to together as the “Beneficiaries”); and 

WHEREAS, pursuant to the Underwriting Agreement, a portion of the Property equal to $8,750,000, or $10,062,500 if the Underwriters’
option to purchase additional units is exercised in full, is attributable to deferred underwriting discounts and commissions that will be payable by the Company to the Underwriters upon the consummation of the Business Combination (as defined below)
(the “Deferred Discount”); and 
 WHEREAS, the Company and the Trustee desire to enter into this Agreement to set
forth the terms and conditions pursuant to which the Trustee shall hold the Property. 
 NOW THEREFORE, IT IS AGREED: 

 

	1.	 Agreements and Covenants of Trustee. The Trustee hereby agrees and covenants to: 



(a)     Hold the Property in trust for the Beneficiaries in accordance with the terms of this Agreement in the Trust
Account established by the Trustee in the United States at J.P. Morgan 












 
Chase Bank, N.A. (or at another U.S chartered commercial bank with consolidated assets of $100 billion or more) and at a brokerage institution selected by the Trustee that is reasonably
satisfactory to the Company; 
 (b)     Manage, supervise and administer the Trust Account subject to the terms and
conditions set forth herein; 
 (c)     In a timely manner, upon the written instruction of the Company, invest and
reinvest the Property in United States government securities within the meaning of Section 2(a)(16) of the Investment Company Act of 1940, as amended, having a maturity of 185 days or less, or in money market funds meeting the conditions of
paragraphs (d)(1), (d)(2), (d)(3) and (d)(4) of Rule 2a-7 promulgated under the Investment Company Act of 1940, as amended (or any successor rule), which invest only in direct U.S. government treasury
obligations, as determined by the Company; the Trustee may not invest in any other securities or assets, it being understood that the Trust Account will earn no interest while account funds are uninvested awaiting the Company’s instructions
hereunder and the Trustee may earn bank credits or other consideration; 
 (d)     Collect and receive, when due, all
principal, interest or other income arising from the Property, which shall become part of the “Property,” as such term is used herein; 

(e)     Promptly notify the Company and the Representative of all communications received by the Trustee with respect to
any Property requiring action by the Company; 
 (f)     Supply any necessary information or documents as may be
requested by the Company (or its authorized agents) in connection with the Company’s preparation of the tax returns relating to assets held in the Trust Account or in connection with the preparation or completion of the audit of the
Company’s financial statements by the Company’s auditors; 
 (g)     Participate in any plan or proceeding for
protecting or enforcing any right or interest arising from the Property if, as and when instructed by the Company to do so; 

(h)     Render to the Company monthly written statements of the activities of, and amounts in, the Trust Account
reflecting all receipts and disbursements of the Trust Account; 
 (i)     Commence liquidation of the Trust Account
only after and promptly after (x) receipt of, and only in accordance with, the terms of a letter from the Company (“Termination Letter”) in a form substantially similar to that attached hereto as either Exhibit A
or Exhibit B, as applicable, signed on behalf of the Company by its Chief Executive Officer, President, Chief Operating Officer, Chairman or Co-Chaiman or other authorized officer of the Company, and
complete the liquidation of the Trust Account and distribute the Property in the Trust Account, including interest earned on the funds held in the Trust Account and not previously released to us to pay our taxes (less up to $100,000 of interest to
pay dissolution expenses), only as directed in the Termination Letter and the other documents referred to therein, or (y) upon the date which is the later of (1) 24 months after the closing of the Offering and (2) such later date as may be
approved by the Company’s shareholders in accordance with the Company’s amended and restated memorandum and articles of association, if a Termination Letter has not been received by the Trustee prior to such date, in which case the Trust
Account shall be liquidated in accordance with the procedures set forth in the Termination Letter attached as Exhibit B and the 












 
Property in the Trust Account, including interest earned on the funds held in the Trust Account and not previously released to the Company to pay its taxes (less up to $100,000 of interest to pay
dissolution expenses), shall be distributed to the Public Shareholders of record as of such date It is acknowledged and agreed that there should be no reduction in the principal amount per share initially deposited in the Trust Account; 

(j)     Upon written request from the Company, which may be given from time to time in a form substantially similar to
that attached hereto as Exhibit C (a “Tax Payment Withdrawal Instruction”), withdraw from the Trust Account and distribute to the Company the amount of interest earned on the Property requested by the Company to cover
any tax obligation owed by the Company as a result of assets of the Company or interest or other income earned on the Property, which amount shall be delivered directly to the Company by electronic funds transfer or other method of prompt payment,
and the Company shall forward such payment to the relevant taxing authority, so long as there is no reduction in the principal amount per share initially deposited in the Trust Account; provided, however, that to the extent there is
not sufficient cash in the Trust Account to pay such tax obligation, the Trustee shall liquidate such assets held in the Trust Account as shall be designated by the Company in writing to make such distribution (it being acknowledged and agreed that
any such amount in excess of interest income earned on the Property shall not be payable from the Trust Account). The written request of the Company referenced above shall constitute presumptive evidence that the Company is entitled to said funds,
and the Trustee shall have no responsibility to look beyond said request; 
 (k)     Upon written request from the
Company, which may be given from time to time in a form substantially similar to that attached hereto as Exhibit D, the Trustee shall distribute to the remitting brokers on behalf of Public Shareholders redeeming Ordinary Shares the amount
required to pay redeemed Ordinary Shares from Public Shareholders pursuant to the Company’s amended and restated memorandum and articles of association; and 

(l)     Not make any withdrawals or distributions from the Trust Account other than pursuant to Section 1(i),
(j) or (k) above. 
  

	2.	 Agreements and Covenants of the Company. The Company hereby agrees and covenants to:



 (a)     Give all instructions to the Trustee hereunder in writing, signed by the Company’s
Chairman or Co-Chairman, Chief Executive Officer, President, Chief Operating Officer or other authorized officer of the Company. In addition, except with respect to its duties under Sections 1(i),
(j) or (k) hereof, the Trustee shall be entitled to rely on, and shall be protected in relying on, any verbal or telephonic advice or instruction which it, in good faith and with reasonable care, believes to be given by any one of
the persons authorized above to give written instructions, provided that the Company shall promptly confirm such instructions in writing; 

(b)     Subject to Section 4 hereof, hold the Trustee harmless and indemnify the Trustee from and against any
and all documented expenses, including reasonable outside counsel fees and disbursements, or losses suffered by the Trustee in connection with any action taken by it hereunder and in connection with any action, suit or other proceeding brought
against the Trustee involving any claim, or in connection with any claim or demand, which in any way arises out of or relates to this Agreement, the services of the Trustee hereunder, or the Property or any interest













 
earned on the Property, except for expenses and losses resulting from the Trustee’s gross negligence, fraud or willful misconduct. Promptly after the receipt by the Trustee of notice of
demand or claim or the commencement of any action, suit or proceeding, pursuant to which the Trustee intends to seek indemnification under this Section 2(b), it shall notify the Company in writing of such claim (hereinafter referred to
as the “Indemnified Claim”). The Trustee shall have the right to conduct and manage the defense against such Indemnified Claim; provided that the Trustee shall obtain the consent of the Company with respect to the
selection of counsel, which consent shall not be unreasonably withheld. The Trustee may not agree to settle any Indemnified Claim without the prior written consent of the Company, which such consent shall not be unreasonably withheld. The Company
may participate in such action with its own counsel; 
 (c)     Pay the Trustee the fees set forth on Schedule A
hereto, including an initial acceptance fee, annual administration fee, and transaction processing fee which fees shall be subject to modification by the parties from time to time. It is expressly understood that the Property shall not be used to
pay such fees unless and until it is distributed to the Company pursuant to Sections 1(i) through 1(k) hereof. The Company shall pay the Trustee the initial acceptance fee and the first annual administration fee at the consummation of
the Offering. The Company shall not be responsible for any other fees or charges of the Trustee except as set forth in this Section 2(c) and as may be provided in Section 2(b) hereof; 

(d)     In connection with any vote of the Company’s shareholders regarding a merger, share exchange, asset
acquisition, share purchase, reorganization or similar business combination involving the Company and one or more businesses (the “Business Combination”), provide to the Trustee an affidavit or certificate of the inspector of
elections for the shareholder meeting verifying the vote of such shareholders regarding such Business Combination; 

(e)     Provide the Representative with a copy of any Termination Letter(s) and/or any other correspondence that is sent
to the Trustee with respect to any proposed withdrawal from the Trust Account promptly after it issues the same; 

(f)     Unless otherwise agreed between the Company and the Representative, ensure that any Instruction Letter (as defined
in Exhibit A) delivered in connection with a Termination Letter in the form of Exhibit A expressly provides that the Deferred Discount is paid directly to the account or accounts directed by the Representative on behalf of the
Underwriters prior to any transfer of the funds held in the Trust Account to the Company or any other person; 
 (g)    
Instruct the Trustee to make only those distributions that are permitted under this Agreement, and refrain from instructing the Trustee to make any distributions that are not permitted under this Agreement; 

(h)     If the Company seeks to amend any provisions of its amended and restated memorandum and articles of association
(A) to modify the substance or timing of the Company’s obligation to provide holders of the Ordinary Shares the right to have their shares redeemed in connection with the Company’s initial Business Combination or to redeem 100% of the
Ordinary Shares if the Company does not complete its initial Business Combination within the time period set forth therein or (B) with respect to any other provision relating to the rights of holders of the













 
Ordinary Shares (in each case, an “Amendment”), the Company will provide the Trustee with a letter in the form of Exhibit D providing instructions for the
distribution of funds to Public Shareholders who exercise their redemption option in connection with such Amendment; and 

(i)     Within five (5) business days after the Underwriters exercise their option to purchase additional units (or
any unexercised portion thereof) or such option to purchase additional units expires, provide the Trustee with a notice in writing of the total amount of the Deferred Discount. 

 

	3.	 Limitations of Liability. The Trustee shall have no responsibility or liability to:



 (a)     Imply obligations, perform duties, inquire or otherwise be subject to the provisions of any
agreement or document other than this Agreement and that which is expressly set forth herein; 
 (b)     Take any action
with respect to the Property, other than as directed in Section 1 hereof, and the Trustee shall have no liability to any third party except for liability arising out of the Trustee’s gross negligence, fraud or willful misconduct;

 (c)     Institute any proceeding for the collection of any principal and income arising from, or institute, appear in
or defend any proceeding of any kind with respect to, any of the Property unless and until it shall have received written instructions from the Company given as provided herein to do so and the Company shall have advanced or guaranteed to it funds
sufficient to pay any expenses incident thereto; 
 (d)     Change the investment of any Property, other than in
compliance with Section 1 hereof; 
 (e)     Refund any depreciation in principal of any Property; 

(f)     Assume that the authority of any person designated by the Company to give instructions hereunder shall not be
continuing unless provided otherwise in such designation, or unless the Company shall have delivered a written revocation of such authority to the Trustee; 

(g)     The other parties hereto or to anyone else for any action taken or omitted by it, or any action suffered by it to
be taken or omitted, in good faith and in the Trustee’s best judgment, except for the Trustee’s gross negligence, fraud or willful misconduct. The Trustee may rely conclusively and shall be protected in acting upon any order, notice,
demand, certificate, opinion or advice of counsel (including counsel chosen by the Trustee, which counsel may be the Company’s counsel), statement, instrument, report or other paper or document (not only as to its due execution and the validity
and effectiveness of its provisions, but also as to the truth and acceptability of any information therein contained) which the Trustee believes, in good faith and with reasonable care, to be genuine and to be signed or presented by the proper
person or persons. The Trustee shall not be bound by any notice or demand, or any waiver, modification, termination or rescission of this Agreement or any of the terms hereof, unless evidenced by a written instrument delivered to the Trustee, signed
by the proper party or parties and, if the duties or rights of the Trustee are affected, unless it shall give its prior written consent thereto; 












 (h)     Verify the accuracy of the information contained in the
Registration Statement; 
 (i)     Provide any assurance that any Business Combination entered into by the Company or
any other action taken by the Company is as contemplated by the Registration Statement; 
 (j)     File information
returns with respect to the Trust Account with any local, state or federal taxing authority or provide periodic written statements to the Company documenting the taxes payable by the Company, if any, relating to any interest income earned on the
Property; 
 (k)     Prepare, execute and file tax reports, income or other tax returns and pay any taxes with respect
to any income generated by, and activities relating to, the Trust Account, regardless of whether such tax is payable by the Trust Account or the Company, including, but not limited to, tax obligations, except pursuant to Section 1(j)
hereof; or 
 (l)     Verify calculations, qualify or otherwise approve the Company’s written
requests for distributions pursuant to Sections 1(i), 1(j) or 1(k) hereof. 
  

	4.	 Trust Account Waiver. The Trustee has no right of set-off or any
right, title, interest or claim of any kind (“Claim”) to, or to any monies in, the Trust Account, and hereby irrevocably waives any Claim to, or to any monies in, the Trust Account that it may have now or in the future. In
the event the Trustee has any Claim against the Company under this Agreement, including, without limitation, under Section 2(b) or Section 2(c) hereof, the Trustee shall pursue such Claim solely against the Company and its
assets outside the Trust Account and not against the Property or any monies in the Trust Account. 


  

	5.	 Termination. This Agreement shall terminate as follows: 



(a)     If the Trustee gives written notice to the Company that it desires to resign under this Agreement, the Company
shall use its reasonable efforts to locate a successor trustee, pending which the Trustee shall continue to act in accordance with this Agreement. At such time that the Company notifies the Trustee that a successor trustee has been appointed by the
Company and has agreed to become subject to the terms of this Agreement, the Trustee shall transfer the management of the Trust Account to the successor trustee, including but not limited to the transfer of copies of the reports and statements
relating to the Trust Account, whereupon this Agreement shall terminate; provided, however, that in the event that the Company does not locate a successor trustee within ninety (90) days of receipt of the resignation notice from
the Trustee, the Trustee may submit an application to have the Property deposited with any court in the State of New York or with the United States District Court for the Southern District of New York and upon such deposit, the Trustee shall be
immune from any liability whatsoever; or 
 (b)     At such time that the Trustee has completed the liquidation of the
Trust Account and its obligations in accordance with the provisions of Section 1(i) hereof and distributed the Property in accordance with the provisions of the Termination Letter, this Agreement shall terminate except with respect to
Section 2(b). 













	6.	 Miscellaneous. 



(a)     The Company and the Trustee each acknowledge that the Trustee will follow the security procedures set forth below
with respect to funds transferred from the Trust Account. The Company and the Trustee will each restrict access to confidential information relating to such security procedures to authorized persons. Each party must notify the other party
immediately if it has reason to believe unauthorized persons may have obtained access to such confidential information, or of any change in its authorized personnel. In executing funds transfers, the Trustee shall rely upon all information supplied
to it by the Company, including, account names, account numbers, and all other identifying information relating to a Beneficiary, Beneficiary’s bank or intermediary bank. Except for any liability arising out of the Trustee’s gross
negligence, fraud or willful misconduct, the Trustee shall not be liable for any loss, liability or expense resulting from any error in the information or transmission of the funds. 

(b)     This Agreement shall be governed by and construed and enforced in accordance with the laws of the State of New
York, without giving effect to conflicts of law principles that would result in the application of the substantive laws of another jurisdiction. This Agreement may be executed in several original or facsimile counterparts, each one of which shall
constitute an original, and together shall constitute but one instrument. 
 (c)     This Agreement contains the entire
agreement and understanding of the parties hereto with respect to the subject matter hereof. Except for Section 1(i), 1(j) and 1(k) hereof (which sections may not be modified, amended or deleted without the affirmative vote
of sixty-five percent (65%) of the then outstanding Ordinary Shares and Class B ordinary shares, par value $0.0001 per share, of the Company, voting together as a single class; provided that no such amendment will affect any Public
Shareholder who has properly elected to redeem his or her Ordinary Shares in connection with a shareholder vote to amend this Agreement to modify the substance or timing of the Company’s obligation to provide for the redemption of the Public
Shares in connection with an initial Business Combination or an Amendment or to redeem 100% of its Ordinary Shares if the Company does not complete its initial Business Combination within the time frame specified in the Company’s amended and
restated memorandum and articles of association), this Agreement or any provision hereof may only be changed, amended or modified (other than to correct a typographical error) by a writing signed by each of the parties hereto. 

(d)     The parties hereto consent to the jurisdiction and venue of any state or federal court located in the City of New
York, State of New York, for purposes of resolving any disputes hereunder. AS TO ANY CLAIM, CROSS-CLAIM OR COUNTERCLAIM IN ANY WAY RELATING TO THIS AGREEMENT, EACH PARTY WAIVES THE RIGHT TO TRIAL BY JURY. 

(e)     Any notice, consent or request to be given in connection with any of the terms or provisions of this Agreement
shall be in writing and shall be sent by express mail or similar private courier service, by certified mail (return receipt requested), by hand delivery or by electronic mail: 

if to the Trustee, to: 

American Stock Transfer & Trust Company, LLC 

6201 15th Ave. 
 Brooklyn, New
York 11219 
 Attn: Relationship Management 

Email: admin12@astfinancial.com 












 if to the Company, to: 

Supernova Partners Acquisition Company III, Ltd. 

4301 50th Street NW 
 Suite 300
PMB 1044 
 Washington, D.C. 20016 

Attn: Michael S. Clifton 
 Email:
michael@supernovaspac.com 
 with copies to: 

Latham & Watkins LLP 

555 Eleventh Street, NW, Suite 1000 

Washington, D.C. 20004 
 Attn:
Patrick H. Shannon; Jason M. Licht 
 Email: patrick.shannon@lw.com 

  jason.licht@lw.com 

and 
 Latham & Watkins
LLP 
 811 Main Street, Suite 3700 

Houston, Texas 77002 
 Attn: Ryan
J. Maierson 
 Email: ryan.maierson@lw.com 

and 
 if to the Underwriters,
to: 
 J.P. Morgan Securities LLC 

383 Madison Avenue 
 New York, New
York 10179 
 Attn: Equity Syndicate Desk 

and 
 Jefferies LLC 

520 Madison Avenue 
 New York, New
York 10022 
 Attention: General Counsel 












 (f)     Each of the Company and the Trustee hereby represents that it
has the full right and power and has been duly authorized to enter into this Agreement and to perform its respective obligations as contemplated hereunder. The Trustee acknowledges and agrees that it shall not make any claims or proceed against the
Trust Account, including by way of set-off, and shall not be entitled to any funds in the Trust Account under any circumstance. 

(g)     This Agreement is the joint product of the Trustee and the Company and each provision hereof has been subject to
the mutual consultation, negotiation and agreement of such parties and shall not be construed for or against any party hereto. 

(h)     This Agreement may be executed in any number of counterparts, each of which shall be deemed to be an original, but
all such counterparts shall together constitute one and the same instrument. Delivery of a signed counterpart of this Agreement by facsimile or electronic transmission shall constitute valid and sufficient delivery thereof. 

(i)     Each of the Company and the Trustee hereby acknowledges and agrees that the Representative on behalf of the
Underwriters is a third-party beneficiary of this Agreement. 
 (j)     Except as specified herein, no party to this
Agreement may assign its rights or delegate its obligations hereunder to any other person or entity. 
 [Signature Page Follows] 












 IN WITNESS WHEREOF, the parties have duly executed this Investment Management Trust
Agreement as of the date first written above. 
  

			
	AMERICAN STOCK TRANSFER & TRUST
	COMPANY, LLC as Trustee
		
	By:	 	 /s/ Michael Legregin

	Name:	 	Michael Legregin
	Title:	 	Senior Vice President
	
	SUPERNOVA PARTNERS ACQUISITION
	COMPANY III, LTD.
		
	By:	 	 /s/ Michael S. Clifton

	Name:	 	Michael S. Clifton
	Title:	 	Chief Financial Officer



  
 [Signature Page to
Investment Management Trust Agreement] 













 SCHEDULE A 
  

							
	 Fee Item
	  	 Time and method of payment
	  	Amount	 
	Initial acceptance fee	  	Initial closing of IPO by wire transfer	  	$	3,500.00	 
	Annual fee	  	First year, initial closing of IPO by wire transfer; thereafter on the anniversary of the effective date of the IPO by wire transfer or check	  	$	10,000.00	 
	Transaction processing fee for disbursements to Company under Sections 1(i), (j), and (k)	  	Billed by Trustee to Company under Section 1	  	$	250.00	 
			
	Paying Agent services as required pursuant to Section 1(i) and 1(k)	  	Billed to Company upon delivery of service pursuant to Section 1(i) and 1(k)	  	 	Prevailing rates	 













 EXHIBIT A 

[Letterhead of Company] 
 [Insert
date] 
 American Stock Transfer & Trust Company, LLC 

6201 15th Ave. 
 Brooklyn, New York 11219 

Attn: Relationship Management 
 Re: Trust
Account - Termination Letter 
 Dear [●]: 

Pursuant to Section 1(i) of the Investment Management Trust Agreement between Supernova Partners Acquisition Company III, Ltd.
(the “Company”) and American Stock Transfer & Trust Company (“Trustee”), dated as of March 22, 2021 (the “Trust Agreement”), this is to advise you that the Company
has entered into an agreement with                      (the “Target Business”) to consummate a business combination with
Target Business (the “Business Combination”) on or about [insert date]. The Company shall notify you at least seventy-two (72) hours in advance of the actual date (or
such shorter time period as you may agree) of the consummation of the Business Combination (the “Consummation Date”). Capitalized terms used but not defined herein shall have the meanings set forth in the Trust Agreement.

 In accordance with the terms of the Trust Agreement, we hereby authorize you to commence to liquidate all of the assets of the Trust
Account, and to transfer the proceeds into the trust operating account at [●] to the effect that, on the Consummation Date, all of the funds held in the Trust Account will be immediately available for transfer to the account or accounts that
the Representative (with respect to the Deferred Discount) and the Company shall direct on the Consummation Date. It is acknowledged and agreed that while the funds are on deposit in said trust operating account at [●] awaiting distribution,
neither the Company nor the Representative will earn any interest or dividends. 
 On the Consummation Date (i) counsel for the Company
shall deliver to you written notification that the Business Combination has been consummated, or will be consummated substantially concurrently with your transfer of funds to the accounts as directed by the Company (the
“Notification”), and (ii) the Company shall deliver to you (a) a certificate by the Chief Executive Officer, Chief Financial Officer or other authorized officer of the Company, which verifies that the Business
Combination has been approved by a vote of the Company’s shareholders, if a vote is held and (b) joint written instruction signed by the Company and the Representative with respect to the transfer of the funds held in the Trust Account,
including payment of the Deferred Discount from the Trust Account (the “Instruction Letter”). You are hereby directed and authorized to transfer the funds held in the Trust Account immediately upon your receipt of the
Notification and the Instruction Letter, in accordance with the terms of the Instruction Letter. In the event that certain deposits held in the Trust Account may not be liquidated by the Consummation Date without penalty, you will notify the Company
in writing of the same and the Company shall direct you as to whether such funds should remain in the 












 
Trust Account and be distributed after the Consummation Date to the Company. Upon the distribution of all the funds, net of any payments necessary for reasonable unreimbursed expenses related to
liquidating the Trust Account, your obligations under the Trust Agreement shall be terminated. 
 In the event that the Business Combination
is not consummated on the Consummation Date described in the notice thereof and we have not notified you on or before the original Consummation Date of a new Consummation Date, then upon receipt by the Trustee of written instructions from the
Company, the funds held in the Trust Account shall be reinvested as provided in Section 1(c) of the Trust Agreement on the business day immediately following the Consummation Date as set forth in such notice as soon thereafter as
possible. 
  

							
		 		 	Very truly yours,
			
		 		 	Supernova Partners Acquisition Company III, Ltd.
				
		 		 	By:	 	
                     
                                         
                                    

		 		 	Name:	 	
		 		 	Title:	 	

  

	cc:	 [●] 














 EXHIBIT B 

[Letterhead of Company] 

[Insert date] 

American Stock Transfer & Trust Company, LLC 
 6201 15th
Ave. 
 Brooklyn, New York 11219 
 Attn: Relationship Management

 Re: Trust Account - Termination Letter 

Ladies and Gentlemen: 
 Pursuant to
Section 1(i) of the Investment Management Trust Agreement between Supernova Partners Acquisition Company III, Ltd. (the “Company”) and American Stock Transfer & Trust Company (the
“Trustee”), dated as of March 22, 2021 (the “Trust Agreement”), this is to advise you that the Company has been unable to effect a business combination with a Target Business (the
“Business Combination”) within the time frame specified in the Company’s Amended and Restated Memorandum and Articles of Association, as described in the Company’s Prospectus relating to the Offering. Capitalized
terms used but not defined herein shall have the meanings set forth in the Trust Agreement. 
 In accordance with the terms of the Trust
Agreement, we hereby authorize you to liquidate all of the assets in the Trust Account and to transfer the total proceeds into the trust operating account at J.P. Morgan Chase Bank, N.A. to await distribution to the Public Shareholders. The Company
has selected                      as the effective date for the purpose of determining the Public Shareholders that will be entitled to receive their
share of the liquidation proceeds. It is acknowledged that no interest will be earned by the Company on the liquidation proceeds while on deposit in the trust operating account You agree to be the Paying Agent of record and, in your separate
capacity as Paying Agent, agree to distribute said funds directly to the Company’s Public Shareholders in accordance with the terms of the Trust Agreement and the Amended and Restated Memorandum and Articles of Association of the Company. Upon
the distribution of all the funds, net of any payments necessary for reasonable unreimbursed expenses related to liquidating the Trust Account, your obligations under the Trust Agreement shall be terminated, except to the extent otherwise provided
in Section 1(j) of the Trust Agreement. 
  

							
		 		 	Very truly yours,
			
		 		 	Supernova Partners Acquisition Company III, Ltd.
				
		 		 	By:	 	
                     
                                         
                                    

		 		 	Name:	 	
		 		 	Title:	 	

  

	cc:	 [●] 














 EXHIBIT C 

[Letterhead of Company] 
 [Insert
date] 
 American Stock Transfer & Trust Company, LLC 

6201 15th Ave. 
 Brooklyn, New York 11219 

Attn: Relationship Management 
 Re: Trust
Account - Tax Payment Withdrawal Instruction 
 Ladies and Gentlemen: 

Pursuant to Section 1(j) of the Investment Management Trust Agreement between Supernova Partners Acquisition Company III, Ltd. (the
“Company”) and American Stock Transfer & Trust Company (the “Trustee”), dated as of March 22, 2021 (the “Trust Agreement”), the Company hereby requests that you
deliver to the Company $         of the interest income earned on the Property as of the date hereof. Capitalized terms used but not defined herein shall have the meanings set forth in the Trust Agreement.

 The Company needs such funds to pay for the tax obligations as set forth on the attached tax return or tax statement. In accordance with
the terms of the Trust Agreement, you are hereby directed and authorized to transfer (via wire transfer) such funds promptly upon your receipt of this letter to the Company’s operating account at: 

 

							
		 		 	[WIRE INSTRUCTION INFORMATION]
			
		 		 	Very truly yours,
			
		 		 	Supernova Partners Acquisition Company III, Ltd.
				
		 		 	By:	 	
                     
                                     

		 		 	Name:	 	
		 		 	Title:	 	

  

	cc:	 [●] 














 EXHIBIT D 

[Letterhead of Company] 
 [Insert
date] 
 American Stock Transfer & Trust Company, LLC 

6201 15th Ave. 
 Brooklyn, New York 11219 

Attn: Relationship Management 
 Re: Trust
Account - Tax Payment Withdrawal Instruction 
 Ladies and Gentlemen: 

Pursuant to Section 1(k) of the Investment Management Trust Agreement between Supernova Partners Acquisition Company III, Ltd.
(the “Company”) and American Stock Transfer & Trust Company (the “Trustee”), dated as of March 22, 2021 (the “Trust Agreement”), the Company hereby
requests that you deliver to the Company’s shareholders $         of the principal and interest income earned on the Property as of the date hereof. Capitalized terms used but not defined herein shall
have the meanings set forth in the Trust Agreement. 
 Pursuant to Section 1(k) of the Trust Agreement, this is to advise you that the Company has
sought an Amendment. Accordingly, in accordance with the terms of the Trust Agreement, we hereby authorize you to liquidate a sufficient portion of the Trust Account and to transfer $[●] of the proceeds of the Trust Account to the trust
operating account at [●] for distribution to the shareholders that have requested redemption of their shares in connection with such Amendment. 
  

							
		 		 	Very truly yours,
			
		 		 	Supernova Partners Acquisition Company III, Ltd.
				
		 		 		 	
                     
                                         
                                    

				
		 		 	By:	 	
	 cc:   [●]
	 		 	Name:	 	
		 		 	Title: