2 - Shares or in the form first made available to the Underwriters by the Company to meet requests of purchasers pursuant to Rule 173 under the Securities Act. As used herein, “Applicable Time” is 9:00 p.m. (New York City time) on January 2, 2024. As...

Exhibit 1.1 15,790,000 Shares Arrowhead Pharmaceuticals, Inc. UNDERWRITING AGREEMENT January 2, 2024 XXXXXXXXX LLC BOFA SECURITIES, INC. XXXXX AND COMPANY, LLC As Representatives of the several Underwriters c/x Xxxxxxxxx LLC 000 Xxxxxxx Xxxxxx Xxx Xxxx, Xxx Xxxx 00000 c/o BofA Securities, Inc. One Bryant Park New York, New York 10036 c/x Xxxxx and Company, LLC 000 Xxxxxxxxx Xxxxxx 00xx Xxxxx Xxx Xxxx, Xxx Xxxx 00000 Ladies and Gentlemen: Introductory. Arrowhead Pharmaceuticals, Inc., a Delaware corporation (the “Company”), proposes to issue and sell to the several underwriters named in Schedule A (the “Underwriters”) an aggregate of 15,790,000 shares of its common stock, par value $0.001 per share (the “Shares”). The 15,790,000 Shares to be sold by the Company are called the “Offered Shares.” Xxxxxxxxx LLC (“Jefferies”), BofA Securities, Inc. (“BofA”) and Xxxxx and Company, LLC (“Cowen”) have agreed to act as representatives of the several Underwriters (in such capacity, the “Representatives”) in connection with the offering and sale of the Offered Shares. To the extent there are no additional underwriters listed on Schedule A, the term “Representatives” as used herein shall mean you, as Underwriters, and the term “Underwriters” shall mean either the singular or the plural, as the context requires. The Company has prepared and filed with the Securities and Exchange Commission (the “Commission”) a shelf registration statement on Form S-3, File No. 333-268665, including a base prospectus (the “Base Prospectus”) to be used in connection with the offering and sale of the Offered Shares. Such registration statement, as amended, including the financial statements, exhibits and schedules thereto, in the form in which it became effective under the Securities Act of 1933, as amended, and the rules and regulations promulgated thereunder (collectively, the “Securities Act”), including all documents incorporated or deemed to be incorporated by reference therein and any information deemed to be a part thereof at the time of effectiveness pursuant to Rule 430A or 430B under the Securities Act, is called the “Registration Statement.” Any registration statement filed by the Company pursuant to Rule 462(b) under the Securities Act in connection with the offer and sale of the Offered Shares is called the “Rule 462(b) Registration Statement,” and, from and after the date and time of filing of any such Rule 462(b) Registration Statement, the term “Registration Statement” shall include the Rule 462(b) Registration Statement. As used herein, the term “Prospectus” shall mean the final prospectus supplement to the Base Prospectus that describes the Offered Shares and the offering thereof (the “Final Prospectus Supplement”), together with the Base Prospectus, in the form first used by the Underwriters to confirm sales of the Offered

- 2 - Shares or in the form first made available to the Underwriters by the Company to meet requests of purchasers pursuant to Rule 173 under the Securities Act. As used herein, “Applicable Time” is 9:00 p.m. (New York City time) on January 2, 2024. As used herein, “free writing prospectus” has the meaning set forth in Rule 405 under the Securities Act, and “Time of Sale Prospectus” means the Base Prospectus, as amended or supplemented immediately prior to the Applicable Time, together with the free writing prospectuses, if any, identified in Schedule B hereto. As used herein, “Road Show” means a “road show” (as defined in Rule 433 under the Securities Act) relating to the offering of the Offered Shares contemplated hereby that is a “written communication” (as defined in Rule 405 under the Securities Act). All references in this Agreement to the Registration Statement, any preliminary prospectus, the Base Prospectus and the Prospectus shall include the documents incorporated or deemed to be incorporated by reference therein. All references in this Agreement to financial statements and schedules and other information which are “contained,” “included” or “stated” in, or “part of” the Registration Statement, the Rule 462(b) Registration Statement, any preliminary prospectus, the Base Prospectus, the Time of Sale Prospectus or the Prospectus, and all other references of like import, shall be deemed to mean and include all such financial statements and schedules and other information which is or is deemed to be incorporated by reference in the Registration Statement, the Rule 462(b) Registration Statement, any preliminary prospectus, the Base Prospectus, the Time of Sale Prospectus or the Prospectus, as the case may be. All references in this Agreement to amendments or supplements to the Registration Statement, any preliminary prospectus, the Base Prospectus, the Time of Sale Prospectus or the Prospectus shall be deemed to mean and include the filing of any document under the Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder (collectively, the “Exchange Act”) that is or is deemed to be incorporated by reference in the Registration Statement, any preliminary prospectus, the Base Prospectus, or the Prospectus, as the case may be. All references in this Agreement to (i) the Registration Statement, any preliminary prospectus, the Base Prospectus or the Prospectus, any amendments or supplements to any of the foregoing, or any free writing prospectus, shall include any copy thereof filed with the Commission pursuant to its Electronic Data Gathering, Analysis and Retrieval System (“XXXXX”) and (ii) the Prospectus shall be deemed to include any “electronic Prospectus” provided for use in connection with the offering of the Offered Shares as contemplated by Section 3(n) of this Agreement. In the event that the Company has only one subsidiary, then all references herein to “subsidiaries” of the Company shall be deemed to refer to such single subsidiary, mutatis mutandis. The Company hereby confirms its agreements with the Underwriters as follows: Section 1. Representations and Warranties of the Company. The Company hereby represents, warrants and covenants to each Underwriter, as of the date of this Agreement, as of the Closing Date (as hereinafter defined) as follows: (a) Compliance with Registration Requirements. The Registration Statement has become effective under the Securities Act. The Company has complied, to the Commission’s satisfaction, with all requests of the Commission for additional or supplemental information, if any. No stop order suspending the effectiveness of the Registration Statement is in effect, and no proceedings for such purpose have been instituted or are pending or, to the best knowledge of the Company, are contemplated or threatened by the Commission. At the time the Company’s Annual Report on Form 10-K for the fiscal year ended September 30, 2023 (the “Annual Report”) was filed with the Commission, or, if later, at the time the Registration Statement was originally filed with the Commission, as well as at the time the Company or any person acting on its behalf (within the meaning, for this clause only, of Rule 163(c) under the Securities Act) made any offer relating to the Offered Shares in reliance on the exemption of Rule 163 under the Securities Act, the Company was a “well known seasoned issuer” as defined in Rule 405 under the Securities Act. The Registration Statement is an “automatic shelf registration statement,” as defined in Rule 405 under the

- 4 - (d) Distribution of Offering Material By the Company. Prior to the completion of the Underwriters’ distribution of the Offered Shares, the Company has not distributed and will not distribute any offering material in connection with the offering and sale of the Offered Shares other than the Registration Statement, the Time of Sale Prospectus, the Prospectus, any free writing prospectus reviewed and consented to by the Representatives or the free writing prospectuses, if any, identified on Schedule B hereto. (e) The Underwriting Agreement. This Agreement has been duly authorized, executed and delivered by the Company. (f) Authorization of the Offered Shares. The Offered Shares have been duly authorized for issuance and sale pursuant to this Agreement and, when issued and delivered by the Company against payment therefor pursuant to this Agreement, will be validly issued, fully paid and nonassessable, and the issuance and sale of the Offered Shares is not subject to any preemptive rights, rights of first refusal or other similar rights to subscribe for or purchase the Offered Shares. (g) No Applicable Registration or Other Similar Rights. There are no persons with registration or other similar rights to have any equity or debt securities registered for sale under the Registration Statement or included in the offering contemplated by this Agreement. (h) No Material Adverse Change. Except as otherwise disclosed in the Registration Statement, the Time of Sale Prospectus and the Prospectus, subsequent to the respective dates as of which information is given in the Registration Statement, the Time of Sale Prospectus and the Prospectus: (i) there has been no material adverse change, or any development that could reasonably be expected to result in a material adverse change, in (A) the condition, financial or otherwise, or in the earnings, business, properties, operations, assets, liabilities or prospects, whether or not arising from transactions in the ordinary course of business, of the Company and its subsidiaries, considered as one entity or (B) the ability of the Company to consummate the transactions contemplated by this Agreement or perform its obligations hereunder (any such change being referred to herein as a “Material Adverse Change”); (ii) the Company and its subsidiaries, considered as one entity, have not incurred any material liability or obligation, indirect, direct or contingent, including without limitation any losses or interference with its business from fire, explosion, flood, earthquakes, accident or other calamity, whether or not covered by insurance, or from any strike, labor dispute or court or governmental action, order or decree, that are material, individually or in the aggregate, to the Company and its subsidiaries, considered as one entity, or entered into any material transactions not in the ordinary course of business; and (iii) there has not been any material decrease in the capital stock or any material increase in any short-term or long-term indebtedness of the Company or its subsidiaries, and there has been no dividend or distribution of any kind declared, paid or made by the Company or, except for dividends paid to the Company or other subsidiaries, by any of the Company’s subsidiaries on any class of capital stock, or any repurchase or redemption by the Company or any of its subsidiaries of any class of capital stock. (i) Independent Accountants. (i) Rose, Xxxxxx & Xxxxxx, LLP, which has expressed its opinion with respect to the financial statements (which term as used in this Agreement includes the related notes thereto) filed with the Commission as a part of the Registration Statement, the Time of Sale Prospectus and the Prospectus, is (i) an independent registered public accounting firm as required by the Exchange Act, and the rules of the Public Company Accounting Oversight Board (“PCAOB”), (ii) in compliance with the applicable requirements relating to the qualification of accountants under Rule 2-01 of Regulation S-X under the Securities Act and (iii) a registered public accounting firm as defined by the PCAOB whose registration has not been suspended or revoked and who has not requested such registration to be withdrawn.

- 15 - (tt) No Contract Terminations. Except as otherwise disclosed in the Registration Statement or the Prospectus, neither the Company nor any of its subsidiaries has sent or received any communication regarding termination of, or intent not to renew, any of the contracts or agreements referred to or described in any preliminary prospectus, the Prospectus or any free writing prospectus, or referred to or described in, or filed as an exhibit to, the Registration Statement, or any document incorporated by reference therein, and no such termination or non-renewal has been threatened by the Company or any of its subsidiaries or, to the Company’s knowledge, any other party to any such contract or agreement, which threat of termination or non-renewal has not been rescinded as of the date hereof. (uu) Dividend Restrictions. No subsidiary of the Company is prohibited or restricted, directly or indirectly, from paying dividends to the Company, or from making any other distribution with respect to such subsidiary’s equity securities or from repaying to the Company or any other subsidiary of the Company any amounts that may from time to time become due under any loans or advances to such subsidiary from the Company or from transferring any property or assets to the Company or to any other subsidiary. Any certificate signed by any officer of the Company or any of its subsidiaries and delivered to the Underwriters or to counsel for the Underwriters in connection with the offering, or the purchase and sale, of the Offered Shares shall be deemed a representation and warranty by the Company to the Underwriters as to the matters covered thereby. The Company has a reasonable basis for making each of the representations set forth in this Section 1. The Company acknowledges that the Underwriters and, for purposes of the opinions to be delivered pursuant to Section 6 hereof, counsel to the Company and counsel to the Underwriters, will rely upon the accuracy and truthfulness of the foregoing representations and hereby consents to such reliance. Section 2. Purchase, Sale and Delivery of the Offered Shares. (a) The Offered Shares. Upon the terms herein set forth, the Company agrees to issue and sell to the Underwriters an aggregate of 15,790,000 Offered Shares. On the basis of the representations, warranties and agreements herein contained, and upon the terms but subject to the conditions herein set forth, the Underwriters agree, severally and not jointly, to purchase from the Company the Offered Shares set forth opposite their names on Schedule A. The purchase price per Offered Share to be paid by the Underwriters to the Company shall be $27.2175 per share. (b) The Closing Date. Delivery of certificates for the Offered Shares to be purchased by the Underwriters and payment therefor shall be made at the offices of Xxxxxx & Xxxxxxx LLP (or such other place as may be agreed to by the Company and the Representatives) at 10:00 a.m. New York City time, on January 5, 2024, or such other time and date not later than 1:30 p.m. New York City time, on January 5, 2024 as the Representatives shall designate by notice to the Company (the time and date of such closing are called the “Closing Date”). The Company hereby acknowledges that circumstances under which the Representatives may provide notice to postpone the Closing Date as originally scheduled include, but are not limited to, any determination by the Company or the Representatives to recirculate to the public copies of an amended or supplemented Prospectus or a delay as contemplated by the provisions of Section 11. (c) [Reserved]. (d) Offering of the Offered Shares. The Underwriters hereby advise the Company that the Underwriters intend to offer for sale to the purchasers, initially on the terms set forth in the Registration

- 16 - Statement, the Time of Sale Prospectus and the Prospectus, the Offered Shares as soon after this Agreement has been executed as Jefferies, in its sole judgment, has determined is advisable and practicable. (e) Payment for the Offered Shares. Payment for the Offered Shares shall be made at the Closing Date by wire transfer of immediately available funds to the order of the Company. It is understood that the Representatives have been authorized, for their own account and the accounts of the several Underwriters, to accept delivery of and receipt for, and make payment of the purchase price for, the Offered Shares the Underwriters have agreed to purchase. Each of Jefferies, BofA and Xxxxx individually and not as the Representatives of the Underwriters, may (but shall not be obligated to) make payment for any Offered Shares to be purchased by any Underwriter whose funds shall not have been received by the Representatives by the Closing Date for the account of such Underwriter, but any such payment shall not relieve such Underwriter from any of its obligations under this Agreement. (f) Delivery of the Offered Shares. The Company shall deliver, or cause to be delivered to the Representatives for the accounts of the several Underwriters certificates for the Offered Shares at the Closing Date, against release of a wire transfer of immediately available funds for the amount of the purchase price therefor. If the Representatives so elect, delivery of the Offered Shares may be made by credit to the accounts designated by the Representatives through The Depository Trust Company’s full fast transfer or DWAC programs. If the Representatives so elect, the certificates for the Offered Shares shall be registered in such names and denominations as the Representatives shall have requested at least two full business days prior to the Closing Date and shall be made available for inspection on the business day preceding the Closing Date at a location in New York City as the Representatives may designate. Time shall be of the essence, and delivery at the time and place specified in this Agreement is a further condition to the obligations of the Underwriters. Section 3. Additional Covenants of the Company. The Company further covenants and agrees with the Underwriters as follows: (a) Commission Filing Fees. The Company agrees to pay the required Commission filing fees relating to the Offered Shares within the time required by Rule 456(b)(1) under the Securities Act without regard to the proviso therein and otherwise in accordance with the Rules 456(b) and 457(r) under the Securities Act. (b) Delivery of Registration Statement, Time of Sale Prospectus and Prospectus. The Company shall furnish to you in New York City, without charge, prior to 10:00 a.m. New York City time on the business day next succeeding the date of this Agreement and during the period when a prospectus relating to the Offered Shares is required by the Securities Act to be delivered (whether physically or through compliance with Rule 172 under the Securities Act or any similar rule) in connection with sales of the Offered Shares, as many copies of the Time of Sale Prospectus, the Prospectus and any supplements and amendments thereto or to the Registration Statement as you may reasonably request. (c) Review of Proposed Amendments and Supplements. During the period when a prospectus relating to the Offered Shares is required by the Securities Act to be delivered (whether physically or through compliance with Rule 172 under the Securities Act or any similar rule), the Company (i) will furnish to the Representatives for review, a reasonable period of time prior to the proposed time of filing of any proposed amendment or supplement to the Registration Statement, a copy of each such amendment or supplement and (ii) will not amend or supplement the Registration Statement (including any amendment or supplement through incorporation of any report filed under the Exchange Act) without the Representatives’ prior written consent. Prior to amending or supplementing any preliminary prospectus, the Time of Sale Prospectus or the Prospectus (including any amendment or supplement through incorporation of any report filed under the Exchange Act), the Company shall furnish to the Representatives for review, a reasonable amount of time

- 17 - prior to the time of filing or use of the proposed amendment or supplement, a copy of each such proposed amendment or supplement. The Company shall not file or use any such proposed amendment or supplement without the Representatives’ prior written consent. The Company shall file with the Commission within the applicable period specified in Rule 424(b) under the Securities Act any prospectus required to be filed pursuant to such Rule. (d) Free Writing Prospectuses. The Company shall furnish to the Representatives for review, a reasonable amount of time prior to the proposed time of filing or use thereof, a copy of each proposed free writing prospectus or any amendment or supplement thereto prepared by or on behalf of, used by, or referred to by the Company, and the Company shall not file, use or refer to any proposed free writing prospectus or any amendment or supplement thereto without the Representatives’ prior written consent, which shall not be unreasonably withheld, conditioned or delayed. The Company shall furnish to each Underwriter, without charge, as many copies of any free writing prospectus prepared by or on behalf of, used by or referred to by the Company as such Underwriter may reasonably request. If at any time when a prospectus is required by the Securities Act to be delivered (whether physically or through compliance with Rule 172 under the Securities Act or any similar rule) in connection with sales of the Offered Shares (but in any event if at any time through and including the Closing Date) there occurred or occurs an event or development as a result of which any free writing prospectus prepared by or on behalf of, used by, or referred to by the Company conflicted or would conflict with the information contained in the Registration Statement or included or would include an untrue statement of a material fact or omitted or would omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances prevailing at such time, not misleading, the Company shall promptly amend or supplement such free writing prospectus to eliminate or correct such conflict so that the statements in such free writing prospectus as so amended or supplemented will not include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances prevailing at such time, not misleading, as the case may be; provided, however, that prior to amending or supplementing any such free writing prospectus, the Company shall furnish to the Representatives for review, a reasonable amount of time prior to the proposed time of filing or use thereof, a copy of such proposed amended or supplemented free writing prospectus, and the Company shall not file, use or refer to any such amended or supplemented free writing prospectus without the Representatives’ prior written consent, which shall not be unreasonably withheld, conditioned or delayed. (e) Filing of Underwriters Free Writing Prospectuses. The Company shall not take any action that would result in an Underwriter or the Company being required to file with the Commission pursuant to Rule 433(d) under the Securities Act a free writing prospectus prepared by or on behalf of such Underwriter that such Underwriter otherwise would not have been required to file thereunder. (f) Amendments and Supplements to Time of Sale Prospectus. If the Time of Sale Prospectus is being used to solicit offers to buy the Offered Shares at a time when the Prospectus is not yet available to prospective purchasers, and any event shall occur or condition exist as a result of which it is necessary to amend or supplement the Time of Sale Prospectus so that the Time of Sale Prospectus does not include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances when delivered to a prospective purchaser, not misleading, or if any event shall occur or condition exist as a result of which the Time of Sale Prospectus conflicts with the information contained in the Registration Statement, or if, in the opinion of counsel for the Underwriters, it is necessary to amend or supplement the Time of Sale Prospectus to comply with applicable law, the Company shall (subject to Section 3(c) and Section 3(d) hereof) promptly prepare, file with the Commission and furnish, at its own expense, to the Underwriters and to any dealer upon request, either amendments or supplements to the Time of Sale Prospectus so that the statements in the Time of Sale Prospectus as so amended or supplemented will not include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances when delivered to a

- 18 - prospective purchaser, not misleading or so that the Time of Sale Prospectus, as amended or supplemented, will no longer conflict with the information contained in the Registration Statement, or so that the Time of Sale Prospectus, as amended or supplemented, will comply with applicable law. (g) Certain Notifications and Required Actions. After the date of this Agreement, the Company shall promptly advise the Representatives in writing of: (i) the receipt of any comments of, or requests for additional or supplemental information from, the Commission; (ii) the time and date of any filing of any post-effective amendment to the Registration Statement or any amendment or supplement to any preliminary prospectus, the Time of Sale Prospectus, any free writing prospectus or the Prospectus; (iii) the time and date that any post-effective amendment to the Registration Statement becomes effective; and (iv) the issuance by the Commission of any stop order suspending the effectiveness of the Registration Statement or any post-effective amendment thereto or any amendment or supplement to any preliminary prospectus, the Time of Sale Prospectus or the Prospectus or of any order preventing or suspending the use of any preliminary prospectus, the Time of Sale Prospectus, any free writing prospectus or the Prospectus, or of any proceedings to remove, suspend or terminate from listing or quotation the Shares from any securities exchange upon which they are listed for trading or included or designated for quotation, or of the threatening or initiation of any proceedings for any of such purposes. If the Commission shall enter any such stop order at any time, the Company will use its best efforts to obtain the lifting of such order as soon as reasonably practicable. Additionally, the Company agrees that it shall comply with all applicable provisions of Rule 424(b), Rule 433 and Rule 430B under the Securities Act and will use its reasonable efforts to confirm that any filings made by the Company under Rule 424(b) or Rule 433 were received in a timely manner by the Commission. If, after the date of this Agreement and during any time when a prospectus is required by the Securities Act to be delivered (whether physically or through compliance with Rule 172 under the Securities Act or any similar rule), the Company receives notice pursuant to Rule 401(g)(2) under the Securities Act from the Commission or otherwise ceases to be eligible to use the automatic shelf registration form, the Company shall promptly advise the Representatives in writing of such notice or ineligibility and will (i) promptly file a new registration statement or post-effective amendment on the proper form relating to the Offered Shares, (ii) use its best efforts to cause such registration statement or post-effective amendment to be declared effective by the Commission as soon as practicable and (iii) promptly notify the Representatives in writing of such effectiveness. (h) Amendments and Supplements to the Prospectus and Other Securities Act Matters. If any event shall occur or condition exist, as a result of which it is necessary to amend or supplement the Prospectus so that the Prospectus does not include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances when the Prospectus is delivered (whether physically or through compliance with Rule 172 under the Securities Act or any similar rule) to a purchaser, not misleading, or if in the opinion of the Representatives or counsel for the Underwriters, it is otherwise necessary to amend or supplement the Prospectus to comply with applicable law, the Company agrees (subject to Section 3(c) and Section 3(d)) hereof to promptly prepare, file with the Commission and furnish, at its own expense, to the Underwriters and to any dealer upon request, amendments or supplements to the Prospectus so that the statements in the Prospectus as so amended or supplemented will not include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances when the Prospectus is delivered (whether physically or through compliance with Rule 172 under the Securities Act or any similar rule) to a purchaser, not misleading or so that the Prospectus, as amended or supplemented, will comply with applicable law. Neither the Representatives’ consent to, nor delivery of, any such amendment or supplement shall constitute a waiver of any of the Company’s obligations under Section 3(c) or Section 3(d). (i) Blue Sky Compliance. The Company shall cooperate with the Representatives and counsel for the Underwriters to qualify or register the Offered Shares for sale under (or obtain exemptions from the application of) the state securities or blue sky laws or Canadian provincial securities laws (or other foreign

- 19 - laws) of those jurisdictions designated by the Representatives, shall comply with such laws and shall continue such qualifications, registrations and exemptions in effect so long as required for the distribution of the Offered Shares. The Company shall not be required to qualify as a foreign corporation or to take any action that would subject it to general service of process in any such jurisdiction where it is not presently qualified or where it would be subject to taxation as a foreign corporation. The Company will advise the Representatives promptly of the suspension of the qualification or registration of (or any such exemption relating to) the Offered Shares for offering, sale or trading in any jurisdiction or any initiation or threat of any proceeding for any such purpose, and in the event of the issuance of any order suspending such qualification, registration or exemption, the Company shall use its best efforts to obtain the withdrawal thereof as soon as reasonably practicable. (j) Use of Proceeds. The Company shall apply the net proceeds from the sale of the Offered Shares sold by it in the manner described under the caption “Use of Proceeds” in the Registration Statement, the Time of Sale Prospectus and the Prospectus. (k) Transfer Agent. The Company shall engage and maintain, at its expense, a registrar and transfer agent for the Shares. (l) Earnings Statement. The Company will make generally available to its security holders and to the Representatives as soon as reasonably practicable an earnings statement (which need not be audited) covering a period of at least twelve months beginning with the first fiscal quarter of the Company commencing after the date of this Agreement that will satisfy the provisions of Section 11(a) of the Securities Act and the rules and regulations of the Commission thereunder; provided, however, that the requirements of this Section 3(l) shall be satisfied to the extent that such earnings statement is available on XXXXX. (m) Continued Compliance with Securities Laws. The Company will comply with the Securities Act and the Exchange Act so as to permit the completion of the distribution of the Offered Shares as contemplated by this Agreement, the Registration Statement, the Time of Sale Prospectus and the Prospectus. Without limiting the generality of the foregoing, the Company will, during the period when a prospectus relating to the Offered Shares is required by the Securities Act to be delivered (whether physically or through compliance with Rule 172 under the Securities Act or any similar rule), file on a timely basis with the Commission and the Nasdaq all reports and documents required to be filed under the Exchange Act. (n) Listing. The Company will use its best efforts to list, subject to notice of issuance, the Offered Shares on the Nasdaq. (o) Company to Provide Copy of the Prospectus in Form That May be Downloaded from the Internet. If requested by the Representatives, the Company shall cause to be prepared and delivered, at its expense, within one business day from the effective date of this Agreement, to the Representatives an “electronic Prospectus” to be used by the Underwriters in connection with the offering and sale of the Offered Shares. As used herein, the term “electronic Prospectus” means a form of Time of Sale Prospectus, and any amendment or supplement thereto, that meets each of the following conditions: (i) it shall be encoded in an electronic format, satisfactory to the Representatives, that may be transmitted electronically by the Representatives and the other Underwriters to offerees and purchasers of the Offered Shares; (ii) it shall disclose the same information as the paper Prospectus, except to the extent that graphic and image material cannot be disseminated electronically, in which case such graphic and image material shall be replaced in the electronic Prospectus with a fair and accurate narrative description or tabular representation of such material, as appropriate; and (iii) it shall be in or convertible into a paper format or an electronic format, satisfactory to Jefferies, that will allow investors to store and have continuously ready access to the Prospectus at any future time, without charge to investors (other than any fee charged for subscription to the Internet as a whole and for on-line time). The Company hereby confirms that it has included or will include

- 20 - in the Prospectus filed pursuant to XXXXX or otherwise with the Commission and in the Registration Statement at the time it was declared effective an undertaking that, upon receipt of a request by an investor or his or her representative, the Company shall transmit or cause to be transmitted promptly, without charge, a paper copy of the Prospectus. (p) Agreement Not to Offer or Sell Additional Shares. During the period commencing on and including the date hereof and continuing through and including the 60th day following the date of the Prospectus (such period, as extended as described below, being referred to herein as the “Lock-up Period”), the Company will not, without the prior written consent of the Jefferies (which consent may be withheld in its sole discretion), directly or indirectly: (i) sell, offer to sell, contract to sell or lend any Shares or Related Securities (as defined below); (ii) effect any short sale, or establish or increase any “put equivalent position” (as defined in Rule 16a-1(h) under the Exchange Act) or liquidate or decrease any “call equivalent position” (as defined in Rule 16a-1(b) under the Exchange Act) of any Shares or Related Securities; (iii) pledge, hypothecate or grant any security interest in any Shares or Related Securities; (iv) in any other way transfer or dispose of any Shares or Related Securities; (v) enter into any swap, hedge or similar arrangement or agreement that transfers, in whole or in part, the economic risk of ownership of any Shares or Related Securities, regardless of whether any such transaction is to be settled in securities, in cash or otherwise; (vi) announce the offering of any Shares or Related Securities; (vii) submit or file any registration statement under the Securities Act in respect of any Shares or Related Securities (other than as contemplated by this Agreement with respect to the Offered Shares and other than a registration statement on Form S-8 to register the offer and sale of securities to be issued pursuant to the Company’s 2021 Incentive Plan or an inducement grant award, as permitted by Nasdaq Stock Market Rule 5635); (viii) effect a reverse stock split, recapitalization, share consolidation, reclassification or similar transaction affecting the outstanding Shares; or (ix) publicly announce the intention to do any of the foregoing; provided, however, that the Company may (A) effect the transactions contemplated hereby and (B) issue Shares or options to purchase Shares, or issue Shares upon exercise of options, pursuant to any stock option, stock bonus or other stock plan or arrangement described in the Registration Statement, the Time of Sale Prospectus and the Prospectus or pursuant to the grant of an inducement grant award, as permitted by Nasdaq Stock Market Rule 5635. Notwithstanding anything to the contrary contained in this paragraph, the Company shall be permitted to keep in effect that certain Open Market Sale AgreementSM (the “Sale Agreement”) between the Company and Jefferies LLC, dated as of December 2, 2022, provided no sales shall be made under the Sale Agreement until after the Closing Date. For purposes of the foregoing, “Related Securities” shall mean any options or warrants or other rights to acquire Shares or any securities exchangeable or exercisable for or convertible into Shares, or to acquire other securities or rights ultimately exchangeable or exercisable for, or convertible into, Shares. (q) Future Reports. During the period of five years hereafter, the Company will furnish to the Representatives, c/x Xxxxxxxxx LLC, 000 Xxxxxxx Xxxxxx, Xxx Xxxx, Xxx Xxxx 00000, Attention: Global Head of Syndicate, c/o BofA Securities, Inc., One Bryant Park, New York, New York 10036 and c/x Xxxxx and Company, LLC, 000 Xxxxxxxxx Xxxxxx 00xx Xxxxx, Xxx Xxxx, Xxx Xxxx 00000: (i) as soon as practicable after the end of each fiscal year, copies of the Annual Report of the Company containing the balance sheet of the Company as of the close of such fiscal year and statements of income, stockholders’ equity and cash flows for the year then ended and the opinion thereon of the Company’s independent public or certified public accountants; (ii) as soon as practicable after the filing thereof, copies of each proxy statement, Annual Report on Form 10-K, Quarterly Report on Form 10-Q, Current Report on Form 8-K or other report filed by the Company with the Commission, FINRA or any securities exchange; and (iii) as soon as available, copies of any report or communication of the Company furnished or made available generally to holders of its capital stock; provided, however, that the requirements of this Section 3(q) shall SM “Open Market Sale Agreement” is a service mark of Jefferies LLC

- 23 - the audited and unaudited financial statements and certain financial information contained in the Registration Statement, the Time of Sale Prospectus, and each free writing prospectus, if any. (b) Compliance with Registration Requirements; No Stop Order; No Objection from FINRA. For the period from and after the date of this Agreement and through and including the Closing Date: (i) The Company shall have filed the Prospectus with the Commission (including the information previously omitted from the Registration Statement pursuant to Rule 430B under the Securities Act) in the manner and within the time period required by Rule 424(b) under the Securities Act; (ii) No stop order suspending the effectiveness of the Registration Statement or any post-effective amendment to the Registration Statement shall be in effect, and no proceedings for such purpose shall have been instituted or threatened by the Commission. (iii) If a filing has been made with FINRA, then FINRA shall have raised no objection to the fairness and reasonableness of the underwriting terms and arrangements. (c) No Material Adverse Change. For the period from and after the date of this Agreement and through and including the Closing Date: in the judgment of the Representatives there shall not have occurred any Material Adverse Change. (d) Opinion of Counsel for the Company. On the Closing Date, the Representatives shall have received the opinion and negative assurance letter of Xxxxxx, Xxxx & Xxxxxxxx LLP, counsel for the Company, dated as of such date, in form and substance reasonably satisfactory to the Representatives. (e) Opinion of Intellectual Property Counsel. On the Closing Date, the Representatives shall have received (i) the opinion of Honigman LLC, counsel for the Company with respect to certain intellectual property matters and (ii) the opinion of the Company’s internal intellectual property counsel with respect to certain intellectual property matters, in each case dated as of such date, in form and substance reasonably satisfactory to the Representatives. (f) Opinion of Counsel for the Underwriters. On the Closing Date, the Representatives shall have received the opinion of Xxxxxx & Xxxxxxx LLP, counsel for the Underwriters in connection with the offer and sale of the Offered Shares, in form and substance satisfactory to the Underwriters, dated as of such date. (g) Officers’ Certificate. On the Closing Date, the Representatives shall have received a certificate executed by the Chief Executive Officer or President of the Company and the Chief Financial Officer of the Company, dated as of such date, to the effect set forth in Section 6(b)(ii) and further to the effect that: (i) for the period from and including the date of this Agreement through and including such date, there has not occurred any Material Adverse Change; (ii) the representations, warranties and covenants of the Company set forth in Section 1 of this Agreement are true and correct with the same force and effect as though expressly made on and as of such date; and (iii) the Company has complied with all the agreements hereunder and satisfied all the conditions on its part to be performed or satisfied hereunder at or prior to such date.

- 25 - employee, agent or controlling person may become subject, under the Securities Act, the Exchange Act, other federal or state statutory law or regulation, or the laws or regulations of foreign jurisdictions where Offered Shares have been offered or sold or at common law or otherwise (including in settlement of any litigation, if such settlement is effected with the written consent of the Company), insofar as such loss, claim, damage, liability or expense (or actions in respect thereof as contemplated below) arises out of or is based upon (i) any untrue statement or alleged untrue statement of a material fact contained in the Registration Statement, or any amendment thereto, or the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading; (ii) any untrue statement or alleged untrue statement of a material fact included in any preliminary prospectus, the Time of Sale Prospectus, any free writing prospectus that the Company has used, referred to or filed, or is required to file, pursuant to Rule 433(d) of the Securities Act or the Prospectus (or any amendment or supplement to the foregoing), or the omission or alleged omission to state therein a material fact necessary in order to make the statements, in the light of the circumstances under which they were made, not misleading; or (iii) any act or failure to act or any alleged act or failure to act by any Underwriter in connection with, or relating in any manner to, the Shares or the offering contemplated hereby, and which is included as part of or referred to in any loss, claim, damage, liability or action arising out of or based upon any matter covered by clause (i) or (ii) above; and to reimburse each Underwriter and each such affiliate, director, officer, employee, agent and controlling person for any and all expenses (including the reasonable fees and disbursements of counsel) as such expenses are reasonably incurred by such Underwriter or such affiliate, director, officer, employee, agent or controlling person in connection with investigating, defending, settling, compromising or paying any such loss, claim, damage, liability, expense or action; provided, however, that the foregoing indemnity agreement shall not apply to any loss, claim, damage, liability or expense to the extent, but only to the extent, arising out of or based upon any untrue statement or alleged untrue statement or omission or alleged omission made in reliance upon and in conformity with information relating to any Underwriter furnished to the Company by the Representatives in writing expressly for use in the Registration Statement, any preliminary prospectus, the Time of Sale Prospectus, any such free writing prospectus or the Prospectus (or any amendment or supplement thereto), it being understood and agreed that the only such information consists of the information described in Section 9(b) below. The indemnity agreement set forth in this Section 9(a) shall be in addition to any liabilities that the Company may otherwise have. (b) Indemnification of the Company and its Directors and Officers and Controlling Persons. The Underwriters agree, severally and not jointly, to indemnify and hold harmless the Company, each of its directors, each of its officers who signed the Registration Statement and each person, if any, who controls the Company within the meaning of the Securities Act or the Exchange Act, against any loss, claim, damage, liability or expense, as incurred, to which the Company, or any such director, officer or controlling person may become subject, under the Securities Act, the Exchange Act, other federal or state statutory law or regulation, or the laws or regulations of foreign jurisdictions where Shares have been offered or sold or at common law or otherwise (including in settlement of any litigation, if such settlement is effected with the written consent of such Underwriter), insofar as such loss, claim, damage, liability or expense (or actions in respect thereof as contemplated below) arises out of or is based upon (i) any untrue statement or alleged untrue statement of a material fact contained in the Registration Statement, or any amendment thereto, or any omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading or (ii) any untrue statement or alleged untrue statement of a material fact included in any preliminary prospectus, the Time of Sale Prospectus, any free writing prospectus that the Company has used, referred to or filed, or is required to file, pursuant to Rule 433 of the Securities Act or the Prospectus (or any such amendment or supplement) or the omission or alleged omission to state therein a material fact necessary in order to make the statements, in the light of the circumstances under which they were made, not misleading, in each case to the extent, but only to the extent, that such untrue statement or alleged untrue statement or omission or alleged omission was made in the Registration Statement, such preliminary prospectus, the Time of Sale Prospectus, such free writing prospectus or the Prospectus (or any such amendment or supplement), in reliance upon and in conformity with information

- 30 - Facsimile: (000) 000-0000 Attention: ECM Legal Xxxxx and Company, LLC 000 Xxxxxxxxx Xxxxxx 00xx Xxxxx Xxx Xxxx, Xxx Xxxx 00000 Facsimile: (000) 000-0000 Attention: Head of Equity Capital Markets with a copy to: Xxxxxx & Xxxxxxx LLP 00000 Xxxx Xxxxx Xxxxx Xxx Xxxxx, XX 00000 Facsimile: (000) 000-0000 Attention: Xxxxxxx X. Xxxxxx If to the Company: Arrowhead Pharmaceuticals, Inc. 000 X. Xxxxxxxx Xxxx., Xxxxx 000 Xxxxxxxx, XX 00000 Facsimile: (000) 000-0000 Attention: General Counsel with a copy to: Xxxxxx, Xxxx & Xxxxxxxx LLP Xxx Xxxxxxxxxxx Xxxxxx, Xxxxx 0000 Xxx Xxxxxxxxx, XX 00000 Facsimile: (000) 000-0000 Attention: Xxxx X. Xxxx; Xxxxxxx Xxxxx Any party hereto may change the address for receipt of communications by giving written notice to the others. Section 16. Successors. This Agreement will inure to the benefit of and be binding upon the parties hereto, including any substitute Underwriters pursuant to Section 11 hereof and to the benefit of the affiliates, directors, officers, employees, agents and controlling persons referred to in Section 9 and Section 10, and in each case their respective successors, and no other person will have any right or obligation hereunder. The term “successors” shall not include any purchaser of the Offered Shares as such from any of the Underwriters merely by reason of such purchase. Section 17. Partial Unenforceability. The invalidity or unenforceability of any section, paragraph or provision of this Agreement shall not affect the validity or enforceability of any other section, paragraph or provision hereof. If any section, paragraph or provision of this Agreement is for any reason determined to be invalid or unenforceable, there shall be deemed to be made such minor changes (and only such minor changes) as are necessary to make it valid and enforceable. Section 18. Recognition of the U.S. Special Resolution Regimes. (a) In the event that any Underwriter that is a Covered Entity becomes subject to a proceeding under a U.S. Special Resolution Regime, the transfer from such Underwriter of this Agreement, and any interest and obligation in or under this Agreement, will be effective to the same extent as the transfer would be effective under the U.S. Special Resolution Regime if this Agreement, and any such interest and obligation, were governed by the laws of the United States or a state of the United States.

- 32 - prospectus and the Prospectus (and any amendments and supplements to the foregoing), as contemplated by the Securities Act and the Exchange Act.

[Signature Page to Underwriting Agreement] If the foregoing is in accordance with your understanding of our agreement, kindly sign and return to the Company the enclosed copies hereof, whereupon this instrument, along with all counterparts hereof, shall become a binding agreement in accordance with its terms. Very truly yours, ARROWHEAD PHARMACEUTICALS, INC. By: /s/ Xxxxxxxxxxx Xxxxxxxx Name: Xxxxxxxxxxx Xxxxxxxx Title: President & Chief Executive Officer

[Signature Page to Underwriting Agreement] The foregoing Underwriting Agreement is hereby confirmed and accepted by the Representatives in New York, New York as of the date first above written. XXXXXXXXX LLC BOFA SECURITIES, INC. XXXXX AND COMPANY, LLC Acting as Representatives of the several Underwriters named in the attached Schedule A By: Xxxxxxxxx LLC By: /s/ Xxxxxxx Xxxxxxxx Name: Xxxxxxx Xxxxxxxx Title: Managing Director By: BofA Securities, Inc. By: /s/ Xxxx Xxxx Name: Xxxx Xxxx Title: Co-Head of North America Healthcare; Head of Life Sciences By: Xxxxx and Company, LLC By: /s/ Xxxxx Xxxxxxx Name: Xxxxx Xxxxxxx Title: Managing Director

SCA-1 Schedule A Underwriters Number of Offered Shares to be Purchased Xxxxxxxxx LLC ............................................................ 7,895,000 BofA Securities, Inc. 3,947,500 Xxxxx and Company, LLC 3,947,500 Total ............................................................. 15,790,000

SCB-1 Schedule B Free Writing Prospectuses Included in the Time of Sale Prospectus None.

A-1 Exhibit A Form of Lock-up Agreement Lock-up Agreement ________, 2023 XXXXXXXXX LLC BOFA SECURITIES, INC. XXXXX AND COMPANY, LLC As Representatives of the several underwriters named in the Underwriting Agreement c/x Xxxxxxxxx LLC 000 Xxxxxxx Xxxxxx Xxx Xxxx, Xxx Xxxx 00000 c/o BofA Securities, Inc. One Bryant Park New York, New York 10036 c/x Xxxxx and Company, LLC 000 Xxxxxxxxx Xxxxxx 00xx Xxxxx Xxx Xxxx, Xxx Xxxx 00000 RE: Arrowhead Pharmaceuticals, Inc. (the “Company”) Ladies & Gentlemen: The undersigned is an owner of shares of common stock, par value $0.001 per share, of the Company (“Shares”) or of securities convertible into or exchangeable or exercisable for Shares. The Company proposes to conduct an offering of Shares (the “Offering”) for which Xxxxxxxxx LLC, BofA Securities, Inc. and Xxxxx and Company, LLC will act as representatives (the “Representatives”) of the several underwriters named therein (the “Underwriters”). The undersigned recognizes that the Offering will benefit each of the Company and the undersigned. The undersigned acknowledges that the Underwriters are relying on the representations and agreements of the undersigned contained in this letter agreement in conducting the Offering and, at a subsequent date, in entering into an underwriting agreement (the “Underwriting Agreement”) and other underwriting arrangements with the Company with respect to the Offering. Annex A sets forth definitions for capitalized terms used in this letter agreement that are not defined in the body of this letter agreement. Those definitions are a part of this letter agreement. In consideration of the foregoing, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the undersigned xxxxxx agrees that, during the Lock-up Period, the undersigned will not (and will cause any Family Member not to), without the prior written consent of Jefferies, which may withhold its consent in its sole discretion:

A-2 • Sell or Offer to Sell any Shares or Related Securities currently or hereafter owned either of record or beneficially (as defined in Rule 13d-3 under the Exchange Act) by the undersigned or such Family Member, • enter into any Swap, • make any demand for, or exercise any right with respect to, the registration under the Securities Act of the offer and sale of any Shares or Related Securities, or cause to be filed a registration statement, prospectus or prospectus supplement (or an amendment or supplement thereto) with respect to any such registration, or • publicly announce any intention to do any of the foregoing. The foregoing will not apply to the registration of the offer and sale of the Shares, and the sale of the Shares to the Underwriters, in each case as contemplated by the Underwriting Agreement. The foregoing will not apply to: (A) the establishment of a new trading plan pursuant to Rule 10b5-1 under the Exchange Act providing for dispositions or sales of Shares, provided that (x) such plan does not permit dispositions or sales of Shares or any Related Securities during the Lock-up Period and (y) no public announcement or filing regarding such plan is required to be made, or is voluntarily made, during the Lock-Up Period by or on behalf of the Company or the undersigned; (B) sales or transfers of Shares made pursuant to a trading plan pursuant to Rule 10b5-1 under the Exchange Act that has been entered into by the undersigned prior to the date of this letter agreement, provided, that a copy of such plan has been made available to the Representatives and, provided further, that no public announcement or filing under the Exchange Act is voluntarily made by or on behalf of the undersigned or the Company and, provided further, that to the extent a public announcement or filing under the Exchange Act, if any, is required by or on behalf of the undersigned or the Company regarding any such sales or transfers, such announcement or filing shall include a statement to the effect that the sale or transfer was made pursuant to a trading plan pursuant to Rule 10b5- 1; (C) the exercise of options to purchase Shares granted under any stock incentive plan or stock purchase plan of the Company, provided that the underlying Shares shall continue to be subject to the restrictions on transfer set forth in this letter agreement and provided further that any filing under Section 16(a) of the Exchange Act with regard to this clause (C) shall clearly indicate in the footnotes thereto that the filing relates to the circumstances described in this clause (C), and no other public announcement shall be required or shall be made voluntarily in connection with such exercise); (D) the transfer of Shares (or any security convertible into Shares) to the Company or sold in connection with a vesting event of the Company’s securities or upon the exercise of options to purchase the Company’s securities, on a “cashless” or “net exercise” basis or to cover tax withholding obligations of the undersigned in connection with such vesting or exercise provided that any filing under Section 16(a) of the Exchange Act with regard to this clause (D) shall clearly indicate in the footnotes thereto that the filing relates to the circumstances described in this clause (D), and no other public announcement shall be required or shall be made voluntarily in connection with such exercise; (E) the transfer or disposition of the undersigned’s Shares (or any Related Securities) that occurs by operation of law, such as pursuant to a qualified domestic order or in connection with a divorce settlement provided that each transferee shall sign and deliver a lock-up agreement substantially in the form of this letter agreement; (F) the transfer of Shares (or any Related Securities) pursuant to a bona fide third party tender offer, merger, consolidation or other similar transaction made to all holders of the Shares involving a change of control of the Company provided that in the event that the tender offer, merger, consolidation or other such transaction is not completed, the Shares owned by the undersigned shall remain subject to the restrictions contained in this letter agreement; or (G) by bona fide gift, provided that each donee executes and delivers to the Representatives an agreement in form and substance satisfactory to the Representatives stating that such transferee is receiving and holding such Shares and/or Related Securities subject to the provisions of this letter agreement and agrees not to Sell or Offer to Sell such Shares and/or Related Securities, engage in any Swap or engage in any other activities restricted under this letter agreement except in accordance with this letter agreement (as if such transferee had been an original signatory hereto). In addition, the foregoing restrictions shall not apply to the transfer of Shares or Related Securities by (i) will

A-3 or intestate succession to a legal representative, heir, beneficiary or Family Member, (ii) to a trust whose beneficiaries consist exclusively of one or more of the undersigned and/or a Family Member, (iii) to any corporation, partnership, limited liability company, investment fund or other entity controlled or managed, or under common control or management by the undersigned or a Family Member, or (iv) as distributions to partners, members or stockholders of the undersigned; provided, however, that in any such case, it shall be a condition to such transfer that: • each transferee executes and delivers to the Representatives an agreement in form and substance satisfactory to the Representatives stating that such transferee is receiving and holding such Shares and/or Related Securities subject to the provisions of this letter agreement and agrees not to Sell or Offer to Sell such Shares and/or Related Securities, engage in any Swap or engage in any other activities restricted under this letter agreement except in accordance with this letter agreement (as if such transferee had been an original signatory hereto), and • prior to the expiration of the Lock-up Period, no public disclosure or filing under the Exchange Act by any party to the transfer (transferor or transferee) shall be required, or made voluntarily, reporting a reduction in beneficial ownership of Shares in connection with such transfer (other than a filing on a Form 5). The undersigned also agrees and consents to the entry of stop transfer instructions with the Company’s transfer agent and registrar against the transfer of Shares or Related Securities held by the undersigned and the undersigned’s Family Members, if any, except in compliance with the foregoing restrictions. With respect to the Offering only, from the date hereof until the expiration of the lock up period, the undersigned waives any registration rights relating to registration under the Securities Act of the offer and sale of any Shares and/or any Related Securities owned either of record or beneficially by the undersigned, including any rights to receive notice of the Offering. The undersigned confirms that the undersigned has not, and has no knowledge that any Family Member has, directly or indirectly, taken any action designed to or that might reasonably be expected to cause or result in the stabilization or manipulation of the price of any security of the Company to facilitate the sale of the Shares. The undersigned will not, and will cause any Family Member not to take, directly or indirectly, any such action. The undersigned acknowledges and agrees that the Underwriters have not provided any recommendation or investment advice nor have the Underwriters solicited any action from the undersigned with respect to the Offering and the undersigned has consulted their own legal, accounting, financial, regulatory and tax advisors to the extent deemed appropriate. Whether or not the Offering occurs as currently contemplated or at all depends on market conditions and other factors. The Offering will only be made pursuant to the Underwriting Agreement, the terms of which are subject to negotiation between the Company and the Representatives. The undersigned hereby represents and warrants that the undersigned has full power, capacity and authority to enter into this letter agreement. This letter agreement is irrevocable and will be binding on the undersigned and the successors, heirs, personal representatives and assigns of the undersigned. This letter agreement and related restrictions shall automatically terminate upon the earliest to occur, if any, of (a) the Representatives, on the one hand, or the Company, on the other hand, advising the other in writing that it has determined not to proceed with the Offering, (b) the termination of the Underwriting Agreement before the sale of any Shares to the Underwriters or (c) January 31, 2024, if the Offering has not closed by such date.

A-4 This letter agreement shall be governed by, and construed in accordance with, the laws of the State of New York. This letter agreement may be delivered via facsimile, electronic mail (including pdf or any electronic signature complying with the U.S. federal ESIGN Act of 2000, e.g. xxx.xxxxxxxx.xxx or xxx.xxxxxxxx.xxx) or other transmission method and any counterpart so delivered shall be deemed to have been duly and validly delivered and be valid and effective for all purposes.

A-5 Signature Printed Name of Person Signing (Indicate capacity of person signing if signing as custodian or trustee, or on behalf of an entity)

A-6 Annex A Certain Defined Terms Used in Lock-up Agreement For purposes of the letter agreement to which this Annex A is attached and of which it is made a part: • “Call Equivalent Position” shall have the meaning set forth in Rule 16a-1(b) under the Exchange Act. • “Exchange Act” shall mean the Securities Exchange Act of 1934, as amended. • “Family Member” shall mean the spouse of the undersigned, an immediate family member of the undersigned or an immediate family member of the undersigned’s spouse, in each case living in the undersigned's household or whose principal residence is the undersigned's household (regardless of whether such spouse or family member may at the time be living elsewhere due to educational activities, health care treatment, military service, temporary internship or employment or otherwise). “Immediate family member” as used above shall have the meaning set forth in Rule 16a-1(e) under the Exchange Act. • “Lock-up Period” shall mean the period beginning on the date hereof and continuing through the close of trading on the date that is 60 days after the date of the Prospectus (as defined in the Underwriting Agreement). • “Put Equivalent Position” shall have the meaning set forth in Rule 16a-1(h) under the Exchange Act. • “Related Securities” shall mean any options or warrants or other rights to acquire Shares or any securities exchangeable or exercisable for or convertible into Shares, or to acquire other securities or rights ultimately exchangeable or exercisable for or convertible into Shares. • “Securities Act” shall mean the Securities Act of 1933, as amended. • “Sell or Offer to Sell” shall mean to: – sell, offer to sell, contract to sell or lend, – effect any short sale or establish or increase a Put Equivalent Position or liquidate or decrease any Call Equivalent Position, – pledge, hypothecate or grant any security interest in, or – in any other way transfer or dispose of, in each case whether effected directly or indirectly. • “Swap” shall mean any swap, hedge or similar arrangement or agreement that transfers, in whole or in part, the economic risk of ownership of Shares or Related Securities, regardless of whether any such transaction is to be settled in securities, in cash or otherwise. Capitalized terms not defined in this Annex A shall have the meanings given to them in the body of this lock-up agreement.

B-1 Exhibit B Directors and Officers Signing Lock-up Agreement Directors: Xxxxxxxx Xxxxx Xxxxx Xxxxxxx Xxxxxx Xxxxxxxx Xxxxxxx X. Xxxxx Xxxxxxxx Xxxxxxxx Xxxxxxx Xxxxxxx Officers: Xxxxxxxxxxx Xxxxxxxx (also a Director) Xxxxxxx X. Xxxxxxxxxx Xxxxxxx O’Xxxxx Xxxxxx San Xxxxxx Xxxxx Xxxxxxxx Xxxxxx Xxxxxx