ARROWHEAD PHARMACEUTICALS, INC.

To the Board of Directors and Stockholders

Arrowhead Pharmaceuticals, Inc.:

Opinion on the Consolidated Financial Statements

We have audited the accompanying consolidated balance sheets of Arrowhead Pharmaceuticals, Inc. and subsidiaries (the Company) as of September 30, 2025 and 2024, the related consolidated statements of operations and comprehensive income (loss), stockholders’ equity, and cash flows for each of the years in the two-year period ended September 30, 2025, and the related notes (collectively, the consolidated financial statements). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company as of September 30, 2025 and 2024, and the results of its operations and its cash flows for each of the years in the two-year period ended September 30, 2025, in conformity with U.S. generally accepted accounting principles.

We also have audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the Company’s internal control over financial reporting as of September 30, 2025, based on criteria established in Internal Control – Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission, and our report dated November 25, 2025 expressed an unqualified opinion on the effectiveness of the Company’s internal control over financial reporting.

These consolidated financial statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on these consolidated financial statements based on our audits. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement, whether due to error or fraud. Our audits included performing procedures to assess the risks of material misstatement of the consolidated financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the consolidated financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the consolidated financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matters

The critical audit matters communicated below are matters arising from the current period audit of the consolidated financial statements that were communicated or required to be communicated to the audit committee and that: (1) relate to accounts or disclosures that are material to the consolidated financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matters below, providing separate opinions on the critical audit matters or on the accounts or disclosures to which they relate.

Sufficiency of audit evidence over valuation of future royalty sales liability

As discussed in Note 13 to the consolidated financial statements, the Company records the obligations under the Royalty Pharma Agreement with Royalty Pharma Investments (RPI) at carrying value using the effective interest method. The Company amortizes the sale of future royalties utilizing the prospective method to estimate future royalties to be paid by the Company to RPI over the life of the arrangement. The Company periodically assesses the amount and timing of expected royalty payments using a combination of internal projections and forecasts from external sources. To the extent such payments differ from the Company’s initial estimates, the Company will prospectively adjust the amortization of the royalty obligation and the effective interest rate. The estimate of the carrying value of the liability related to the sale of future royalties is derived from the estimate of future sales of olpasiran and the probability of success assumption. The estimate of future sales of olpasiran is based on key assumptions such as patient population, market penetration, olpasiran sales price, and the comparable guideline drug. The liability related to the sale of future royalties was $367,397 thousand as of September 30, 2025.

We identified the evaluation of the sufficiency of audit evidence over the determination of the carrying value of the liability related to the sale of future royalties as a critical audit matter. Subjective auditor judgment was required to evaluate the sufficiency of audit evidence obtained because of the level of audit effort associated with evaluating the carrying value of the liability related to the sale of future royalties.

The following are the primary procedures we performed to address this critical audit matter. We applied auditor judgment to determine the nature and extent of procedures to be performed over the evaluation of the carrying value of the liability related to the sale of future royalties. We evaluated the design and tested the operating effectiveness of certain internal controls related to management’s valuation process, including the determination of the key assumptions into the carrying value of the liability related to the sale of future royalties as described above. We assessed the patient population and market penetration assumptions by comparing to independently sourced external market and industry data. We performed sensitivity analyses over the estimated olpasiran sales price and probability of success using independently sourced external market and industry data and evaluated the impact of changes in those assumptions on the carrying value of the liability related to the sale of future royalties. We assessed the reasonableness of the comparable guideline drug by evaluating against drugs similar to olpasiran in the marketplace. We evaluated the sufficiency of audit evidence obtained by assessing the cumulative results of the audit procedures performed and potential bias in the accounting estimate, including the appropriateness of the nature and extent of such evidence.

Evaluation of distinct performance obligations related to the license and collaboration agreement with Sarepta Therapeutics, Inc

As discussed in Notes 1 and 2 to the consolidated financial statements, the Company entered into an Exclusive License and Collaboration Agreement with Sarepta Therapeutics, Inc. (Sarepta). At contract inception, the Company assesses whether the goods or services promised within the contract are distinct and, therefore, represent a separate performance obligation, or whether they are not distinct and are combined with other goods and services until a distinct bundle is identified. The Company then determines the transaction price and allocates it to each performance obligation. The Company identified 17 performance obligations under the license and collaboration agreement with Sarepta. Fixed consideration of $833.6 million and an estimated variable consideration of $71.2 million were allocated to all performance obligations based on their relative standalone selling price.

We identified the evaluation of distinct performance obligations, including understanding the nature and significance of the contractual obligations and their standalone selling prices, related to the license and collaboration agreement with Sarepta as a critical audit matter. Subjective and complex auditor judgment was required to assess the Company’s identification of distinct performance obligations, including evaluating the rights and obligations described in the agreement, their benefit to the customer, and the level of modification or customization among the performance obligations. In addition, subjective auditor judgment was required to evaluate certain significant assumptions in the discounted cash flow model used by management to determine the standalone selling prices of the distinct performance obligations, including the discount rate and certain forecasted expenses. The audit effort associated with assessing the discount rate assumption required specialized skills and knowledge.

The following are the primary procedures we performed to address this critical audit matter. We evaluated the design and tested the operating effectiveness of certain internal controls related to the Company’s revenue recognition process, including management’s identification of distinct performance obligations in the license and collaboration agreement and determination of the standalone selling prices. We evaluated management’s identification of distinct performance obligations and the significance of the contractual obligations by obtaining and reading the license and collaboration agreement to gain an understanding of the contractual terms and conditions and the commitments being made in the agreement. We conducted inquiries with personnel responsible for clinical development to understand the nature of the research and development activities specific to the clinical, preclinical, and discovery stage programs to evaluate the nature of the commitments made to the customer. We evaluated certain forecasted expenses within the discounted cash flow model by comparing such amounts to external market and industry data. We involved valuation professionals with specialized skills and knowledge, who assisted in the assessment of the discount rate within the discounted cash flow model by comparing it to a discount rate that was independently developed using publicly available market data for comparable companies.

KPMG LLP

We have served as the Company’s auditor since 2024.

San Diego, California

November 25, 2025

To the Board of Directors and Stockholders

Arrowhead Pharmaceuticals, Inc.:

Opinion on Internal Control Over Financial Reporting

We have audited Arrowhead Pharmaceuticals, Inc. and subsidiaries' (the Company) internal control over financial reporting as of September 30, 2025, based on criteria established in Internal Control – Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission. In our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of September 30, 2025, based on criteria established in Internal Control – Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission.

We also have audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the consolidated balance sheets of the Company as of September 30, 2025 and 2024, the related consolidated statements of operations and comprehensive income (loss), stockholders’ equity, and cash flows for each of the years in the two-year period ended September 30, 2025, and the related notes (collectively, the consolidated financial statements), and our report dated November 25, 2025 expressed an unqualified opinion on those consolidated financial statements.

The Company’s management is responsible for maintaining effective internal control over financial reporting and for its assessment of the effectiveness of internal control over financial reporting, included in the accompanying Management's Annual Report on Internal Control over Financial Reporting. Our responsibility is to express an opinion on the Company’s internal control over financial reporting based on our audit. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audit in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether effective internal control over financial reporting was maintained in all material respects. Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audit also included performing such other procedures as we considered necessary in the circumstances. We believe that our audit provides a reasonable basis for our opinion.

Definition and Limitations of Internal Control Over Financial Reporting

A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

KPMG LLP

San Diego, California

November 25, 2025