Document:

EX-10.2

 Exhibit 10.2 

February 8, 2021 
 GigCapital4, Inc. 

1731 Embarcadero Rd., Suite 200 
 Palo Alto, CA 94303 

Oppenheimer & Co. Inc. 
 85 Broad Street 

New York, New York 10004 
 Nomura Securities International, Inc.

 Worldwide Plaza 
 309 West 49th Street 

New York, New York 
 10019-7316 

Re: Initial Public Offering 
 Ladies
and Gentlemen: 
 This letter agreement (this “Letter Agreement”) is being delivered to you in accordance with the
Underwriting Agreement (the “Underwriting Agreement”) entered into by and between GigCapital4, Inc., a Delaware corporation (the “Company”), and Oppenheimer & Co. Inc. and Nomura Securities
International, Inc., as representatives (the “Representatives”) of the several underwriters named therein (the “Underwriters”), relating to an underwritten initial public offering (the
“IPO”) of 31,200,000 units (the “Initial Units”) of the Company, and up to an additional 4,680,000 units (together with the Initial Units, the “Units”) in the event that the Underwriters’ 45-day over-allotment option is exercised in full or in part, each Unit consisting of one share of the Company’s common stock, par value $0.0001 per share
(“Common Stock” and such shares included in the Units, the “Offering Shares”), and one-third of one redeemable warrant to purchase one share of
Common Stock at a price of $11.50 per share, subject to adjustment (the warrants included in the Units sold, the “Offering Warrants”). Capitalized terms used herein but not defined in context are defined in paragraph 12
hereof. 
 In order to induce the Company and the Underwriters to enter into the Underwriting Agreement and to proceed with the IPO, and in
recognition of the benefit that such IPO will confer upon the undersigned, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, each of the undersigned individuals, being an executive officer
or director of the Company and signing this Letter Agreement in his or her personal capacity and not on behalf of the Company, hereby agrees with the Company and the Underwriters as follows: 

1. With respect to stockholder votes and associated conversion rights, 

(a) if the Company solicits stockholder approval of a Business Combination via a proxy solicitation, then the undersigned will vote all shares
of then outstanding Common Stock beneficially owned by him/her in favor of such Business Combination; provided, that (i) the undersigned acknowledges and agrees that prior to entering into a Business Combination with a target
business that is affiliated with any Insiders, such transaction must be approved by a majority of the Company’s disinterested independent directors and the Company must obtain an opinion from an independent investment banking firm, or another
independent entity that commonly renders valuation opinions on the type of target business the Company is seeking to acquire, that such Business Combination is fair to the Company’s unaffiliated stockholders from a financial point of view, and
(ii) no Insider will be entitled to receive or accept a finder’s fee or any other compensation in the event such Insider originates a Business Combination; 

(b) the undersigned hereby agrees not to propose for a stockholder approval any amendment to the Amended and Restated Certificate of
Incorporation that would (i) affect the substance or timing of the Company’s obligation to redeem 100% of the Offering Shares if the Company does not complete a Business Combination within 24 months of the closing of the IPO letter,
or (ii) alter its provisions relating to the Company’s pre-Business Combination activity or the related stockholders’ rights prior to the consummation of such Business
Combination, unless, in each case, the Company provides the holders of any Offering Shares with the opportunity to redeem their Offering Shares upon the approval of any such amendment. Such redemption must
be at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account including interest (which interest shall be net of franchise and income taxes payable by the Company), divided
by the number of then outstanding Offering Shares; and 

 (c) the undersigned will not redeem any shares of Common Stock beneficially owned by him/her
in connection with a solicitation for stockholder approval described in either of clauses (a) or (b) above, or sell any such shares of Common Stock in a tender offer undertaken by the Company in connection with a Business Combination. 

2. If the Company fails to consummate a Business Combination within 24 months of the completion of the IPO, or such other time period as
may be set forth in the Amended and Restated Certificate of Incorporation, the undersigned will cause the Company to (i) cease all operations except for the purpose of winding up, (ii) as promptly as reasonably possible, but not more than
10 business days thereafter, redeem the Offering Shares at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including
interest earned on the Trust Account (which interest shall be net of taxes payable by the Company and up to $100,000 of interest to pay dissolution expenses), divided by the number of then outstanding Offering Shares, which redemption will
completely extinguish the holders’ rights as stockholders (including the right to receive further liquidation distributions, if any), and (iii) as promptly as reasonably possible following such redemption, subject to the approval of the
Company’s remaining stockholders and the Company’s board of directors, dissolve and liquidate, subject in the cases of clauses (ii) and (iii) to the Company’s obligations under Delaware law to provide for claims of creditors
and other requirements of applicable law. 
 3. The undersigned hereby waives any and all right, title, interest or claim of any kind the
undersigned may have in the future in or to any distribution of the Trust Account and any remaining assets of the Company as a result of, or arising out of, any contracts or agreements with the Company and will not seek recourse against the Trust
Account for any reason whatsoever; provided, that the foregoing waiver shall not apply with respect to liquidating distributions from the Trust Account made in connection with any Offering Shares purchased by the undersigned
or its Affiliates during the IPO or on the open market after the completion of the IPO if the Company fails to complete a Business Combination within 24 months of the completion of the IPO. The undersigned acknowledges and agrees that there
will be no distribution from the Trust Account with respect to any of the Offering Warrants, all rights of which will terminate upon the Company’s liquidation. 

4. In order to minimize potential conflicts of interest that may arise from multiple corporate affiliations, 

(a) the undersigned shall present to the Company for its consideration, prior to presentation to any other entity, any target business in the
technology, media and telecommunications industry that has a fair market value of at least 80% of the assets held in the Trust Account (excluding the deferred underwriting commissions and any taxes payable on interest earned), subject to any pre-existing fiduciary or contractual obligations the undersigned might have; and 

(b) the undersigned hereby acknowledges and agrees that (i) each of the Underwriters and the Company may be irreparably injured in the
event of a breach of any of the obligations contained in this Letter Agreement, (ii) monetary damages may not be an adequate remedy for such breach,
and (iii) the non-breaching party shall be entitled to injunctive relief, in addition to any other remedy that such party may have in law or in equity, in the event of such breach.

 5. None of the undersigned or any of their Affiliates will be entitled to receive, and none of them may accept, any compensation or other
cash payment prior to, or for services rendered in order to effectuate, the consummation of the Business Combination, except for the following: 

(a) GigManagement, LLC, a Delaware limited liability company (“Sponsor”), an Affiliate of Drs. Katz and Dinu, and its Affiliates
may receive compensation for administrative services and office space, as provided for under that certain Administrative Services Agreement, dated as of February 1, 2021, between the Company and GigManagement, LLC; 

(b) Sponsor may receive amounts due under that certain promissory note in the aggregate principal amount of $125,000, dated as of
December 21, 2021, issued by the Company in favor of Sponsor; 
 (c) Mr. Weightman may receive compensation for his services as
Chief Financial Officer of the Company, as provided for under that certain Strategic Services Agreement and Confidential Information and Invention Assignment Agreement with the Company dated as of February 1, 2021; 

 (d) Mr. Weightman received 5,000 shares of Common Stock and Ms. Hayes received
10,000 shares of Common Stock (the “Insider Shares”) as consideration for the future services as Chief Financial Officer and our director, respectively, which after the adjustment for a 1.2:1 stock split effected on
February 8, 2021, resulted in them holding 6,000 and 12,000 shares of Common Stock, respectively; and 
 (e) any of the undersigned and
their Affiliates may receive reimbursement of out-of-pocket expenses incurred by them in connection with certain activities on behalf of
the Company, such as identifying and investigating possible business targets and business combinations, as well as advisory fees to directors pertaining to board committee service and extraordinary administrative and analytical services, and
repayment upon consummation of a Business Combination of any loans which may be made by them or by their Affiliates to finance transaction costs in connection with an intended Business Combination. While the terms of any such loans have not been
determined nor have any written agreements been executed with respect thereto, it is acknowledged and agreed that up to $1,500,000 of any such loans may be convertible into units of the post-business combination entity at a price of $10.00 per unit
at the option of the lender. 
 6. The undersigned agrees to continue to serve in his or her current capacity as an executive officer and/or
director of the Company until the earlier of the consummation by the Company of a Business Combination or its liquidation. The biographical information of the undersigned previously furnished to the Company and the Representatives is true and
accurate in all respects, does not omit any material information with respect to the undersigned’s background and contains all of the information required to be disclosed pursuant to Item
401 of Regulation S-K, promulgated under the Securities Act. The undersigned’s FINRA Questionnaire previously furnished to the Company and the Representative is also true and
accurate in all respects. 
 7. The undersigned represents and warrants that (i) he or she is not subject to, or a respondent in, any
legal action for any injunction, cease-and-desist order, or order or stipulation to desist or refrain from any act or practice relating to
the offering of securities in any jurisdiction; (ii) he or she has never been convicted of or pleaded guilty to any crime involving any fraud, relating to any financial transaction or handling of funds of another person, or pertaining to any
dealings in any securities and he or she is not currently a defendant in any such criminal proceeding; and (iii) he or she has never been suspended or expelled from membership in any securities or commodities exchange or association, or had a
securities or commodities license or registration denied, suspended or revoked. 
 8. The undersigned agrees that he or she shall not
Transfer (as defined below) any Insider Shares of the Company held by him or her or by his or her Affiliates until the earlier of (i) twelve months after the completion of a Business Combination or (ii) the date on which, subsequent to a
Business Combination, (x) the last sale price of the Common Stock equals or exceeds $12.00 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the like) for any 20 trading days within any 30-trading day period commencing at least 90 days after a Business Combination, or (y) the Company completes a liquidation, merger, stock exchange or other similar
transaction that results in all of the Company’s stockholders having the right to exchange their shares of Common Stock for cash, securities or other property (the
“Lock-up Period”). Notwithstanding the
foregoing, during the Lock-up Period, Transfers of Insider Shares are permitted to be made (a) amongst Sponsor and its Affiliates, to the Company’s executive officers or
directors, or to any Affiliate or family member of any of the Company’s executive officers or directors; (b) in the case of an entity, as a distribution to its partners, stockholders or members upon its liquidation; (c) in the case of
an individual, (1) by bona fide gift to such person’s immediate family or to a trust, the beneficiary of which is a member of such person’s immediate family, an Affiliate of such person or to a charitable organization, (2) by
virtue of the laws of descent and distribution upon death of such person, (3) pursuant to a qualified domestic relations order; (d) by certain pledges to secure obligations incurred in connection with purchases of the Company’s
securities; (e) through private sales or transfers made in connection with the consummation of a Business Combination at prices no greater than the price at which such securities were originally purchased; (f) in the case of an
Underwriter, to such Underwriter’s Affiliates or any entity controlled by such Underwriter; or (g) to the Company for no value for cancellation in connection with the consummation of a Business
Combination; provided, that, in each such case (except clause (g)), these permitted transferees must enter into a written agreement agreeing to be bound by these transfer restrictions and the other terms described in this
Letter Agreement to the extent and for the duration that such terms remain in effect at the time of the Transfer. 

 9. Notwithstanding the foregoing paragraph 8, each of the undersigned agrees that during the
period commencing on the effective date of the Underwriting Agreement and ending 180 days after such date, none of them nor any of their Affiliates, may, without the prior written approval of the Underwriters, offer, sell, contract to sell, pledge,
or otherwise dispose of, directly or indirectly, or hedge the Company’s Units, warrants, shares of Common Stock or any other securities convertible into or exchangeable or exercisable for shares of Common Stock. The foregoing sentence shall not
apply to the registration of the offer and sale of Units contemplated by the Underwriting Agreement and the sale of the Units to the Underwriters. 

10. The undersigned has full right and power, without violating any agreement by which he or she is bound, to enter into this Letter Agreement
and to serve as an executive officer and/or director of the Company. 
 11. This Letter 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. The undersigned hereby (i) agrees that any
action, proceeding or claim against him or her arising out of or relating in any way to this Letter Agreement (a “Proceeding”) shall be brought and enforced in the courts of the State of New York of the United States of
America for the Southern District of New York, and irrevocably submits to such jurisdiction, which jurisdiction shall be exclusive, (ii) waives any objection to such exclusive jurisdiction and that such courts represent an inconvenient forum,
and (iii) irrevocably agrees to appoint DLA Piper LLP (US) as agent for the service of process in the State of New York to receive, for the undersigned and on his or her behalf, service of process in any Proceeding. If for any reason such agent
is unable to act as such, the undersigned will promptly notify the Company and the Representative and appoint a substitute agent acceptable to each of the Company and the Representative within 30 days and nothing in this Letter Agreement will affect
the right of either party to serve process in any other manner permitted by law. 
 12. As used herein, (i)
“Affiliate” has the meaning set forth in Rule 144(a)(1) under the Securities Act; (ii) “Amended and Restated Certificate of Incorporation” refers to the Amended and Restated Certificate of
Incorporation of the Company, as filed with the Secretary of State of the State of Delaware, as the same may be amended from time to time; (iii) a “Business Combination” shall mean a merger, share exchange, asset
acquisition, stock purchase, recapitalization, reorganization or other similar business combination with one or more businesses or entities; (iv) “Exchange Act” means the Securities Exchange Act of 1934, as amended; (v)
“Insiders” means all executive officers and directors of the Company immediately prior to the IPO, as well as Sponsor and any of its Affiliates; (vi) the “Registration Statement” shall mean the
Registration Statement on Form S-1 (Registration No. 333-252315) filed by the Company with the SEC in connection with the IPO, as the same may be amended
or supplemented; (vii) the “Securities Act” means the Securities Act of 1933, as amended; (viii) the “SEC” means the United States Securities and Exchange Commission; (ix)
“Transfer” means (a) the sale of, offer to sell, contract or agreement to sell, hypothecate, pledge, grant of any option to purchase or otherwise dispose of or agreement to dispose of, directly or indirectly, or
establishment or increase of a put equivalent position or liquidation with respect to or decrease of a call equivalent position within the meaning of Section 16 of the Exchange Act and the rules and regulations promulgated thereunder with
respect to any security, (b) the entry into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of any security, whether any such transaction is to be settled by delivery
of such securities, in cash or otherwise, or (c) the public announcement of any intention to effect any transaction specified in clause (a) or (b); and (x) “Trust Account” means the trust account into which a
portion of the net proceeds of the Company’s IPO will be deposited. 
 13. This Letter Agreement constitutes the entire agreement and
understanding of the parties hereto in respect of the subject matter hereof and supersedes all prior understandings, agreements, or representations by or among the parties hereto, written or oral, to the extent they relate in any way to the subject
matter hereof or the transactions contemplated hereby. This Letter Agreement may not be changed, amended, modified or waived (other than to correct a typographical error) as to any particular provision, except by a written instrument executed by all
parties hereto. 
 14. The undersigned acknowledges and understands that the Underwriters and the Company will rely upon the agreements,
representations and warranties set forth herein in proceeding with the IPO. Nothing contained herein shall be deemed to render the Underwriters a representative of, or a fiduciary with respect to, the Company, its stockholders or any creditor or
vendor of the Company with respect to the subject matter hereof. 
 15. This Letter Agreement shall be binding on the undersigned and such
person’s respective successors, heirs, personal representatives and assigns. This Letter Agreement shall terminate on the earlier of (i) the Company’s consummation of a Business Combination, or (ii) the liquidation of the
Company; provided, that such termination shall not relieve the undersigned from liability for any breach of this agreement prior to its termination. 

 16. This Letter Agreement may be executed in counterparts, each of which when so executed
shall be deemed to be an original and all of which when taken together shall constitute one and the same instrument. The words “execution,” signed,” “signature,” and words of like import in this Letter Agreement shall
include images of manually executed signatures transmitted by facsimile or other electronic format (including, without limitation, “pdf”, “tif” or “jpg”) and other electronic signatures (including, without limitation,
DocuSign and AdobeSign). The use of electronic signatures and electronic records (including, without limitation, any contract or other record created, generated, sent, communicated, received, or stored by electronic means) shall be of the same legal
effect, validity and enforceability as a manually executed signature or use of a paper-based record-keeping system to the fullest extent permitted by applicable law, including the Federal Electronic Signatures in Global and National Commerce Act,
the New York State Electronic Signatures and Records Act and any other applicable law, including, without limitation, any state law based on the Uniform Electronic Transactions Act or the Uniform Commercial Code. 

[Signature Page Follows] 

 
	
	Very truly yours,
	
	 /s/ Dr Raluca Dinu

	 Dr Raluca Dinu,
 President, Chief Executive
Officer,
 Secretary, and Director of GigCapital4, Inc.

	
	 /s/ Dr. Avi S. Katz

	Dr. Avi S. Katz
	Executive Chairman of the Board of GigCapital4, Inc.
	
	 /s/ Brad Weightman

	Brad Weightman, Chief Financial Officer of GigCapital4, Inc.
	
	 /s/ Neil Miotto

	Neil Miotto, Director of GigCapital4, Inc.
	
	 /s/ Andrea Betti-Berutto

	Andrea Betti-Berutto, Director of GigCapital4, Inc.
	
	 /s/ Dorothy D. Hayes

	Dorothy D. Hayes, Director of GigCapital4, Inc.

  

	
	Accepted and agreed this 8th day of February, 2021.
	
	GIGCAPITAL4, INC.
	
	/s/ Dr. Raluca Dinu
	 Dr. Raluca Dinu
 Chief Executive Officer
and President

	
	OPPENHEIMER & CO. INC.
	
	 /s/ Lewis Silberman

	 By: Lewis Silberman
 Title: Managing
Director

	
	 NOMURA SECURITIES
 INTERNATIONAL,
INC.

	
	 /s/ James Chenard

	 By: James Chenard
 Title: Managing
Director

 Signature page to Insider Letter (Executive Officers and Directors)EX-10.3

 Exhibit 10.3 

GigCapital4, Inc. 
 1731
Embarcadero Road 
 Suite 200 

Palo Alto, CA 94303 

February 8, 2021 
 RE:
Grant of Insider Shares 
 Dear Mr. Weightman: 

We are pleased that you (“you”) have agreed to serve as the Chief Financial Officer of GigCapital4, Inc., a
Delaware corporation (the “Company”). In exchange for your future services as the Chief Financial Officer, you are hereby granted 5,000 shares (the “Insider Shares”) of the common stock, par value
$0.0001 per share (“Common Stock”), of the Company, pursuant to the terms of this agreement (this “Agreement”), as follows: 

1. Grant of Insider Shares. Solely in consideration for your future services as the Chief Financial Officer of the Company, the
Company hereby grants the Insider Shares to you. The Company will deliver to you a certificate registered in your name representing the Insider Shares. 

2. Representations, Warranties and Agreements. 

2.1. Your Representations, Warranties and Agreements. To induce the Company to issue the Insider Shares to you, you hereby
represent and warrant to the Company and agree with the Company as follows: 
 2.1.1. No Government Recommendation or Approval.
You understand that no federal or state agency has passed upon or made any recommendation or endorsement of the offering of the Insider Shares. 

2.1.2. No Conflicts. The execution, delivery and performance of this Agreement and the consummation by you of the transactions
contemplated hereby do not violate, conflict with or constitute a default under (i) any agreement, indenture or instrument to which you are a party, (ii) any law, statute, rule or regulation to which you are subject, or (iii) any
agreement, order, judgment or decree to which you are subject. 
 2.1.3. Organization and Authority. You possess all requisite
power and authority necessary to carry out the transactions contemplated by this Agreement. Upon execution and delivery by you, this Agreement will be a legal, valid and binding agreement of you, enforceable against you in accordance with its terms,
except as such enforceability may be limited by applicable bankruptcy, insolvency, fraudulent conveyance or similar laws affecting the enforcement of creditors’ rights generally and subject to general principles of equity (regardless of whether
enforcement is sought in a proceeding at law or in equity). 
 2.1.4. Experience, Financial Capability and Suitability. You are:
(i) sophisticated in financial matters and is able to evaluate the risks and benefits of the acquisition of the Insider Shares and (ii) able to bear the economic risk of such acquisition of the Insider Shares for an indefinite period of
time because the Insider Shares have not been registered under the Securities Act of 1933, as amended (the “Securities Act”), and therefore cannot be resold unless subsequently registered under the Securities Act or an
exemption from such registration is available. You are capable of evaluating the merits and risks of such acquisition of the Insider Shares and have the capacity to protect your own interests. You must bear the economic risk of the Insider Shares
until the Insider Shares are sold pursuant to: (x) an effective registration statement under the Securities Act or (y) an exemption from registration available with respect to such sale. You are able to bear the economic risks and to
afford a complete loss of your investment in the Insider Shares. 
 2.1.5. Access to Information; Independent Investigation.
Prior to the execution of this Agreement, you have had the opportunity to ask questions of and receive answers from representatives of the Company concerning the Company, as well as the finances, operations, business and prospects of the Company,
and the opportunity to obtain additional information to verify the accuracy of all information so obtained. You have relied solely on your own knowledge and understanding of the Company and its business based upon your own due diligence

 
investigation and the information furnished pursuant to this paragraph. You understand that no person has been authorized to give any information or to make any representations which were not
furnished pursuant to this Section 2 and you have not relied on any other representations or information in making your investment decision, whether written or oral, relating to the Company, its operations or its
prospects. 
 2.1.6. Restrictions on Transfer; Shell Company. You understand the Insider Shares are being offered in a
transaction not involving a public offering within the meaning of the Securities Act. You understand the Insider Shares will be “restricted securities” as defined in Rule 144(a)(3) under the Securities Act and you understand that the
certificate representing the Insider Shares will contain a legend in respect of such restrictions. If in the future you decide to offer, resell, pledge or otherwise transfer the Insider Shares, such Insider Shares may be offered, resold, pledged or
otherwise transferred only in accordance with the provisions of Sections 4.1 and 4.2 hereof. You agree that if any transfer of its Insider Shares or any interest therein is proposed to be made, as a condition
precedent to any such transfer, you may be required to deliver to the Company an opinion of counsel satisfactory to the Company. Absent registration or an exemption, you agree not to resell the Insider Shares. You further acknowledge that because
the Company is a shell company, Rule 144 may not be available to you for the resale of the Insider Shares until at least one year following consummation of the initial Business Combination of the Company, despite technical compliance with the
certain requirements of Rule 144 and the release or waiver of any contractual transfer restrictions. For the purposes of this Agreement, the term “Business Combination” means a merger, share exchange, asset acquisition, stock
purchase, recapitalization, reorganization or other similar business combination with one or more businesses or entities. 

3. Waiver of Liquidation Distributions; Redemption Rights. In connection with the Insider Shares granted pursuant to this
Agreement, you hereby waive any and all right, title, interest or claim of any kind in or to any distributions by the Company from the trust account which will be established for the benefit of the Company’s public stockholders and into which
substantially all of the proceeds of the initial public offering of the Company’s equity securities (the “IPO”) will be deposited (the “Trust Account”), in the event of a liquidation of the
Company upon the Company’s failure to timely complete an initial Business Combination. For purposes of clarity, in the event you purchase Common Stock in the IPO or in the aftermarket, any additional Common Stock so granted shall be eligible to
receive any liquidating distributions by the Company. However, in no event will you have the right to redeem any shares of Common Stock into funds held in the Trust Account upon the successful completion of an initial Business Combination. 

4. Restrictions on Transfer. 

4.1. Securities Law Restrictions. In addition to the restrictions set forth in Section 4, you shall not sell, transfer,
pledge, hypothecate or dispose of all or any part of the Insider Shares prior to the date on which the Company completes its initial Business Combination. Notwithstanding the foregoing, you may transfer the Insider Shares to Permitted Transferees as
such term is defined in the Insider Letter (as defined below), provided that such Permitted Transferees must agree in writing to be bound by this Section 4 and such Insider Shares remain subject to forfeiture as provided
in Section 5. You agree not to sell, transfer, pledge, hypothecate or otherwise dispose of all or any part of the Insider Shares unless, prior thereto (a) a registration statement on the appropriate form under the Securities Act and
applicable state securities laws with respect to the Insider Shares proposed to be transferred shall then be effective or (b) the Company has received an opinion from counsel reasonably satisfactory to the Company, that such registration is not
required because such transaction is exempt from registration under the Securities Act and the rules promulgated by the Securities and Exchange Commission thereunder and with all applicable state securities laws. 

4.2. Lock-ups. You acknowledge that the Insider Shares will be subject to restrictions
on transfer (the “Lock-ups”) contained in that certain letter agreement (the “Insider Letter”), of even date herewith, by and between the Company, the
undersigned and each other person who is, as of the date hereof, an executive officer, director or director nominee of the Company, which Insider Letter shall be substantially in the form to be filed as an exhibit to the Registration Statement.

 4.3. Restrictive Legends. All certificates representing the Insider Shares shall have endorsed thereon legends substantially
as follows: 

 “THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED, OR ANY STATE SECURITIES LAWS AND NEITHER THE SECURITIES NOR 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 WHICH, IN THE OPINION OF COUNSEL, IS AVAILABLE.” 
 “THE SECURITIES REPRESENTED BY THIS
CERTIFICATE ARE SUBJECT TO LOCK-UP PROVISIONS AND MAY NOT BE OFFERED, SOLD, TRANSFERRED, PLEDGED OR OTHERWISE DISPOSED DURING THE TERM OF THE LOCKUP PERIOD. ANY TRANSFEREE SHALL BE SUBJECT TO THE RESTRICTIONS
SET FORTH IN THE GRANT AGREEMENT.” 
 4.4. Additional Insider Shares or Substituted Securities. In the event of the
declaration of a stock dividend, the declaration of a special dividend payable in a form other than Common Stock, a spin-off, a stock split, an adjustment in conversion ratio, a recapitalization or a similar
transaction affecting the Company’s outstanding Common Stock without receipt of consideration, any new, substituted or additional securities or other property which are by reason of such transaction distributed with respect to any Insider
Shares subject to Section 4 and Subsections 4.4-4.5, or into which such Insider Shares thereby become convertible shall immediately be subject to this Section 4.
Appropriate adjustments to reflect the distribution of such securities or property shall be made to the number or class of Insider Shares subject to this Section 4. 

4.5. Registration Rights. You acknowledge that the Insider Shares are being acquired pursuant to an exemption from the registration
requirements of the Securities Act and will become freely tradable only after certain conditions are met or they are registered pursuant to a Registration Rights Agreement to be entered into with the Company prior to the closing of the IPO. 

5. Forfeiture. If you cease to serve as the Chief Financial Officer of the Company due to your resignation or removal for
cause at time prior to the date on which the Company completes its initial Business Combination, all of the Insider Shares granted hereunder will be automatically forfeited by you for no consideration and immediately cancelled by the Company. 

6. Voting and Redemption of Insider Shares. You agree to (i) vote the Insider Shares in favor of an initial Business
Combination that the Company negotiates and submits for approval to the Company’s stockholders and shall not seek redemption with respect to such Insider Shares, (ii) not redeem any Insider Shares in connection with a redemption or tender
offer presented to the Company’s stockholders in connection with an initial Business Combination negotiated by the Company and (iii) comply with such other provisions as set forth in the Insider Letter. 

7. Section 83(b) Election. You understand that Section 83(a) of the Internal Revenue Code of 1986, as amended
(the “Code”), taxes as ordinary income the difference between the amount paid for the Insider Shares and the Fair Market Value of the Insider Shares as of the date any restrictions on the Insider Shares lapse. In this context,
“restriction” means the obligation of you to forfeit the Insider Shares as set forth in Section 5 of this Agreement. You understand that you may elect to be taxed at the time the Insider Shares
are purchased, rather than when and as the restriction expires, by filing an election under Section 83(b) (an “83(b) Election”) of the Code with the Internal Revenue Service within thirty (30) days from the date of grant.
Even if the Fair Market Value of the Insider Shares at the time of the execution of this Agreement equals the amount paid for the Insider Shares, the election must be made to avoid income under Section 83(a) in the future. You understand that
failure to file such an election in a timely manner may result in adverse tax consequences for you. You further understand that an additional copy of such election form should be filed with your federal income tax return for the calendar year in
which the date of this Agreement falls. You acknowledge that the foregoing is only a summary of the effect of United States federal income taxation with respect to purchase of the Insider Shares hereunder, and does not purport to be complete. You
further acknowledge that the Company has directed you to seek independent advice regarding the applicable provisions of the Code, the income tax laws of any municipality, state or foreign country in which you may reside, and the tax consequences of
your death. 

 You agree that you will execute and deliver to the Company with this executed Agreement a
copy of the Acknowledgment and Statement of Decision Regarding Section 83(b) Election (the “Acknowledgment”), attached hereto as Exhibit A. You further agree that you will execute and submit with
the Acknowledgment a copy of the 83(b) Election, attached hereto as Exhibit B, if you have indicated in the Acknowledgment your decision to make such an election. 

8. Tax Consequences. You should obtain advice from an appropriate independent professional adviser with respect to, and under the
laws of your country of residence and/or citizenship, the taxation implications of the grant, issuance, purchase, retention, assignment, release, cancellation, sale or any other disposal of the Shares (each, a “Trigger Event”). You
should also obtain advice in respect of the taxation indemnity provisions under Section 7 below. 
 9. Indemnification; Tax
Indemnity. Each party shall indemnify the other against any loss, cost or damages (including reasonable attorneys’ fees and expenses) incurred as a result of such party’s breach of any representation, warranty, covenant or agreement in
this Agreement. Notwithstanding the foregoing or anything herein to the contrary, to the extent permitted by law, you hereby agrees to indemnify and keep indemnified the Company and the Company as trustee for and on behalf of any affiliate entity,
in respect of any liability or obligation of the Company and/or any affiliate entity to account for income tax or any other taxation provisions under the laws of your country of citizenship and/or residence to the extent arising from a Trigger
Event. 
 10. Other Agreements. 

10.1. Further Assurances. You agree to execute such further instruments and to take such further action as may reasonably be
necessary to carry out the intent of this Agreement. 
 10.2. Notices. All notices, statements or other documents which are
required or contemplated by this Agreement shall be in writing and delivered: (i) personally or sent by first class registered or certified mail, overnight courier service or facsimile or electronic transmission to the address designated in
writing, (ii) by facsimile to the number most recently provided to such party or such other address or fax number as may be designated in writing by such party and (iii) by electronic mail, to the electronic mail address most recently
provided to such party or such other electronic mail address as may be designated in writing by such party. Any notice or other communication so transmitted shall be deemed to have been given on the day of delivery, if delivered personally, on the
business day following receipt of written confirmation, if sent by facsimile or electronic transmission, one (1) business day after delivery to an overnight courier service or five (5) days after mailing if sent by mail. 

10.3. Entire Agreement. This Agreement, together with the Insider Letter and the Registration Rights Agreement, embodies the entire
agreement and understanding between you and the Company with respect to the subject matter hereof and supersedes all prior oral or written agreements and understandings relating to the subject matter hereof. No statement, representation, warranty,
covenant or agreement of any kind not expressly set forth in this Agreement shall affect, or be used to interpret, change or restrict, the express terms and provisions of this Agreement. 

10.4. Modifications and Amendments. The terms and provisions of this Agreement may be modified or amended only by written agreement
executed by all parties hereto. 
 10.5. Waivers and Consents. The terms and provisions of this Agreement may be waived, or
consent for the departure therefrom granted, only by written document executed by the party entitled to the benefits of such terms or provisions. No such waiver or consent shall be deemed to be or shall constitute a waiver or consent with respect to
any other terms or provisions of this Agreement, whether or not similar. Each such waiver or consent shall be effective only in the specific instance and for the purpose for which it was given, and shall not constitute a continuing waiver or
consent. 
 10.6. Assignment. The rights and obligations under this Agreement may not be assigned by either party hereto without
the prior written consent of the other party. 

 10.7. Benefit. All statements, representations, warranties, covenants and
agreements in this Agreement shall be binding on the parties hereto and shall inure to the benefit of the respective successors and permitted assigns of each party hereto. Nothing in this Agreement shall be construed to create any rights or
obligations except among the parties hereto, and no person or entity shall be regarded as a third-party beneficiary of this Agreement. 

10.8. Governing Law. This Agreement and the rights and obligations of the parties hereunder shall be construed in accordance with
and governed by the laws of New York applicable to contracts wholly performed within the borders of such state, without giving effect to the conflict of law principles thereof. 

10.9. Severability. In the event that any court of competent jurisdiction shall determine that any provision, or any portion
thereof, contained in this Agreement shall be unreasonable or unenforceable in any respect, then such provision shall be deemed limited to the extent that such court deems it reasonable and enforceable, and as so limited shall remain in full force
and effect. In the event that such court shall deem any such provision, or portion thereof, wholly unenforceable, the remaining provisions of this Agreement shall nevertheless remain in full force and effect. 

10.10. No Waiver of Rights, Powers and Remedies. No failure or delay by a party hereto in exercising any right, power or remedy
under this Agreement, and no course of dealing between the parties hereto, shall operate as a waiver of any such right, power or remedy of such party. No single or partial exercise of any right, power or remedy under this Agreement by a party
hereto, nor any abandonment or discontinuance of steps to enforce any such right, power or remedy, shall preclude such party from any other or further exercise thereof or the exercise of any other right, power or remedy hereunder. The election of
any remedy by a party hereto shall not constitute a waiver of the right of such party to pursue other available remedies. No notice to or demand on a party not expressly required under this Agreement shall entitle the party receiving such notice or
demand to any other or further notice or demand in similar or other circumstances or constitute a waiver of the rights of the party giving such notice or demand to any other or further action in any circumstances without such notice or demand. 

10.11. Survival of Representations and Warranties. All representations and warranties made by the parties hereto in this Agreement
or in any other agreement, certificate or instrument provided for or contemplated hereby, shall survive the execution and delivery hereof and any investigations made by or on behalf of the parties. 

10.12. No Broker or Finder. Each of the parties hereto represents and warrants to the other that no broker, finder or other
financial consultant has acted on its behalf in connection with this Agreement or the transactions contemplated hereby in such a way as to create any liability on the other. Each of the parties hereto agrees to indemnify and hold the other harmless
from any claim or demand for commission or other compensation by any broker, finder, financial consultant or similar agent claiming to have been employed by or on behalf of such party and to bear the cost of legal expenses incurred in defending
against any such claim. 
 10.13. Headings and Captions. The headings and captions of the various sections of this Agreement are
for convenience of reference only and shall in no way modify or affect the meaning or construction of any of the terms or provisions hereof. 

10.14. Counterparts. This Agreement may be executed in one or more counterparts, all of which when taken together shall be
considered one and the same agreement and shall become effective when counterparts have been signed by each party and delivered to the other party, it being understood that both parties need not sign the same counterpart. In the event that any
signature is delivered by facsimile transmission or any other form of electronic delivery, such signature shall create a valid and binding obligation of the party executing (or on whose behalf such signature is executed) with the same force and
effect as if such signature page were an original thereof. 
 10.15. Construction. The words “include,”
“includes,” and “including” will be deemed to be followed by “without limitation.” Pronouns in masculine, feminine, and neuter genders will be construed to include any other gender, and words in the
singular form will be construed to include the plural and vice versa, unless the context otherwise requires. The words “this Agreement,” “herein,” “hereof,” “hereby,”
“hereunder,” and words of similar import refer to this Agreement as a whole and not to any particular section unless expressly so limited. The parties hereto intend that each representation, warranty, and covenant contained herein
will have independent significance. If any party hereto has breached any representation, warranty, or covenant contained herein in any respect, the fact 

 
that there exists another representation, warranty or covenant relating to the same subject matter (regardless of the relative levels of specificity) which such party hereto has not breached will
not detract from or mitigate the fact that such party hereto is in breach of the first representation, warranty, or covenant. 

10.16. Mutual Drafting. This Agreement is the joint product of you 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. 

[Signature Page Follows] 

 If the foregoing accurately sets forth our understanding and agreement, please sign the
enclosed copy of this Agreement and return it to us. 
  

	
	 Very truly yours,
  

GIGCAPITAL4, INC.
  

	 /s/ Dr. Raluca Dinu

	Dr. Raluca Dinu, Chief Executive Officer and President

  

	
	Accepted and agreed this 8th day of February, 2021.
	
	 /s/ Brad Weightman

	Brad Weightman

 Signature Page to Subscription Agreement – Brad Weightman 

 EXHIBIT A 

ACKNOWLEDGMENT AND STATEMENT OF DECISION 

REGARDING SECTION 83(b) ELECTION 

The undersigned (which term includes the undersigned’s spouse), a grantee of 5,000 shares (the “Insider Shares”) of
Common Stock of GigCapital4, Inc., a Delaware corporation (the “Company”), hereby states as follows: 
  

					
	1.	  		  	The undersigned either [check and complete as applicable]:
			
	(a)	  	____	  	has consulted, and has been fully advised by, the undersigned’s own tax advisor, __________________________, whose business address is _____________________________, regarding the federal, state and local tax consequences of
acquiring the Insider Shares, and particularly regarding the advisability of making elections pursuant to Section 83(b) of the Internal Revenue Code of 1986, as amended (the “Code”) and pursuant to the corresponding provisions,
if any, of applicable state law; or
			
	(b)	  	____	  	has knowingly chosen not to consult such a tax advisor.
			
	2.	  		  	The undersigned hereby states that the undersigned has decided [check as applicable]:
			
	(a)	  	____	  	to make an election pursuant to Section 83(b) of the Code, and is submitting to the Company, together with the undersigned’s executed Insider Shares Grant Agreement, an executed form entitled “Election Under
Section 83(b) of the Internal Revenue Code of 1986;” or
			
	(b)	  	____	  	not to make an election pursuant to Section 83(b) of the Code.

 3. Neither the Company nor any subsidiary or representative of the Company has made any warranty or
representation to the undersigned with respect to the tax consequences of the undersigned’s acceptance of Insider Shares or of the making or failure to make an election pursuant to Section 83(b) of the Code or the corresponding provisions,
if any, of applicable state law. 
  

							
	Date:	 	  
	 		 	  

				
	Date:	 	  
	 		 	  

		 		 		 	Spouse of

 EXHIBIT B 

ELECTION UNDER SECTION 83(b) 

OF THE INTERNAL REVENUE CODE OF 1986 

The undersigned taxpayer hereby elects, pursuant to Section 83(b) of the Internal Revenue Code of 1986, as amended, to include in
taxpayer’s gross income for the current taxable year, the amount of any compensation taxable to taxpayer in connection with taxpayer’s receipt of the property described below: 

 

	1.	 The name, address, taxpayer identification number and taxable year of the undersigned are as follows:

 NAME OF TAXPAYER: _____________________ 

NAME OF SPOUSE: _____________________ 

ADDRESS: _____________________________ 

_____________________________ 

IDENTIFICATION NO. OF TAXPAYER: _______________ 

IDENTIFICATION NO. OF SPOUSE: _______________ 

TAXABLE YEAR: _______________ 
  

	2.	 The property with respect to which the election is made is described as follows: 

_______________ shares of the Common Stock of GigCapital4, Inc., a Delaware corporation (the “Company”). 

 

	3.	 The date on which the property was transferred is: _______________ 

 

	4.	 The property is subject to the following restrictions: 

The shares are subject to forfeiture and cancellation by the Company for no consideration upon termination of taxpayer’s employment or
consulting relationship due to taxpayer’s resignation or termination for cause prior to the date of the Company’s initial Business Combination (as defined in the grant agreement). 

 

	5.	 The fair market value at the time of transfer, determined without regard to any restriction other than a
restriction which by its terms will never lapse, of such property is: $_______________. 

  

	6.	 The amount (if any) paid for such property: $______________ 

The undersigned has submitted a copy of this statement to the person for whom the services were performed in connection with the undersigned’s receipt of
the above-described property. The transferee of such property is the person performing the services in connection with the transfer of said property. 

The undersigned understands that the foregoing election may not be revoked except with the consent of the Commissioner. 

 

							
	Dated:	 	  
	 		 	  

				
	Dated:	 	  
	 		 	  

		 		 		 	Spouse of

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