Organization and Significant Accounting Policies	9 Months Ended
Jun. 30, 2026
Accounting Policies [Abstract]
Organization and Significant Accounting Policies	ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES General and Recent Developments Arrowhead Pharmaceuticals, Inc. and its subsidiaries (referred to herein collectively as the “Company”) are primarily engaged in developing medicines that treat intractable diseases by silencing the genes that cause them. Using a broad portfolio of RNA chemistries and efficient modes of delivery, the Company’s therapies trigger the RNA interference mechanism to induce rapid, deep and durable knockdown of target genes. RNA interference (“RNAi”) is a mechanism present in living cells that inhibits the expression of a specific gene, thereby affecting the production of a specific protein. The Company’s RNAi-based therapeutics may leverage this natural pathway of gene silencing to target and shut down specific disease-causing genes. Approved Products REDEMPLO® (plozasiran) is approved by the U.S. Food and Drug Administration (“FDA”) as an adjunct to diet to reduce triglycerides for adults with Familial Chylomicronemia Syndrome (“FCS”). REDEMPLO is also approved by the European Commission, Chinese National Medical Products Administration (“NMPA”), Health Canada, and the Australian Therapeutic Goods Administration (TGA) for the same indication. REDEMPLO is a small interfering RNA (“siRNA”) therapeutic designed to suppress the production of apolipoprotein C-III (APOC3), a protein produced in the liver that raises triglyceride levels by slowing their breakdown and clearance. By targeting the APOC3 gene with sustained silencing, REDEMPLO delivers significant reductions in triglyceride levels. REDEMPLO is the first and only FDA-approved siRNA treatment studied in both genetically confirmed and clinically diagnosed patients living with FCS. Consolidation and Basis of Presentation The interim Consolidated Financial Statements include the accounts of Arrowhead Pharmaceuticals, Inc. and its subsidiaries (wholly-owned subsidiaries and a variable interest entity for which the Company is the primary beneficiary). Wholly-owned subsidiaries refer to Arrowhead Madison, Inc., Arrowhead Australia Pty Ltd., Arrowhead Pharmaceuticals Ireland Limited and Arrowhead Pharmaceuticals NZ Limited. The Company’s variable interest entity is Visirna Therapeutics, Inc. (“Visirna”). For subsidiaries in which the Company owns or is exposed to less than 100% of the economics, the Company records net loss attributable to noncontrolling interests in its consolidated statements of operations equal to the percentage of the economic or ownership interests retained in such entity by the respective noncontrolling party. The interim Consolidated Financial Statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”). The financial data of the Company included herein are unaudited. In the opinion of management, all material adjustments of a normal recurring nature have been made to present fairly the Company’s financial position as of June 30, 2026 and the results of operations and cash flows for the periods presented. All intercompany transactions and balances have been eliminated. Certain prior period amounts have been reclassified to conform with the current period presentation. Certain financial information that is normally included in annual financial statements prepared in accordance with GAAP, but that is not required for interim reporting purposes, has been omitted from the accompanying interim consolidated financial statements and related notes. Readers are urged to review the Company’s Annual Report on Form 10-K for the fiscal year ended September 30, 2025 for more complete descriptions and discussions. Operating results and cash flows for the nine months ended June 30, 2026 are not necessarily indicative of the results that may be expected for the fiscal year ending September 30, 2026. The Company operates as a single segment as the chief operating decision maker (“CODM”), reviews operating results on an aggregate basis and manages the operations as a single operating segment. Refer to Note 16, Segment Information, for further details on the segment information. Liquidity The Company’s primary sources of financing have been through the sale of its equity securities, credit facility, revenue from its licensing and collaboration agreements, the sale of certain future royalties and issuance of convertible debt. Research and development activities have required significant investment since the Company’s inception and are expected to continue to require significant cash expenditure in the future, particularly as the Company’s pipeline of drug candidates and its headcount have both expanded. Additionally, significant investment will be required as a growing commercial-stage Company and as the Company’s pipeline matures into later stage clinical trials. As of June 30, 2026, the Company had $54.8 million in cash, cash equivalents and restricted cash ($4.1 million in restricted cash) and $1,547.2 million in available-for-sale securities to fund operations. In total, the Company is eligible to receive up to $16.2 billion in additional developmental, regulatory and sales milestones based on programs that have been partnered, and may receive various royalties on net sales from its licensing and collaboration agreements, subject to the terms and conditions of those agreements. Summary of Significant Accounting Policies There have been no changes to the significant accounting policies disclosed in the Company’s most recent Annual Report on Form 10-K for the fiscal year ended September 30, 2025, other than below: Equity method investment The Company accounts for investments over which it has significant influence but not control under the equity method. The investment is initially recorded at cost and subsequently adjusted for the Company’s proportionate share of the investee’s net income or loss and are included in other assets in the accompanying consolidated balance sheets. The Company presents income or losses from equity investments as loss on equity method investment on the consolidated statements of operations and comprehensive (loss) income. If the share of losses exceeds the carrying value of the Company’s investment, the Company will suspend recognizing additional losses and will continue to do so unless it commits to providing additional funding or commits to guarantee investee liabilities. As of June 30, 2026, the Company had an equity method investment in Bisirna Therapeutics, Inc. (“Bisirna”). Refer to Note 8, Equity Method Investment, for further details. Convertible debt The Company accounts for its convertible debt instrument as a single unit of accounting, classified as a liability, as the conversion features do not require bifurcation as a derivative under ASC 815-15 and the convertible debt instrument was not issued at a substantial premium. The Company records debt issuance costs as contra-liabilities in the consolidated balance sheets at issuance, and amortizes them over the contractual term of the convertible debt instrument based on the effective interest method. The balance of the convertible notes presented in the consolidated balance sheets represents the principal balance of the convertible debt instrument less the unamortized portion of the debt issuance costs. As of June 30, 2026, the Company had outstanding convertible notes, which mature on January 15, 2032. Refer to Note 14, Convertible Notes, for further details. Recent Accounting Pronouncements In July 2025, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) 2025-05, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Asset. This ASU allows companies to elect a practical expedient to assume that conditions as of the balance sheet date will remain unchanged for the remaining life of the asset when estimating the expected credit losses of the asset. The ASU will become effective for the Company beginning October 1, 2026, and the Company is currently evaluating the impact on its consolidated financial statements and related disclosures. In January 2025, the FASB issued ASU 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses, in November 2024, and ASU 2025-01, Clarifying the Effective Date. These updates require entities to provide disaggregated disclosures of income statement expenses. The ASUs do not affect the expense captions presented on the face of the income statement but instead require the disaggregation of certain expense captions into specified categories within the footnotes to the financial statements. The ASUs will become effective for the Company beginning October 1, 2027, and the Company is currently evaluating the impact on its consolidated financial statements and related disclosures. In November 2024, the FASB issued ASU 2024-04, Debt-Debt with Conversion and Other Options (Subtopic 470-20), which clarifies the requirements for determining whether certain settlements of convertible debt instruments should be accounted for as an induced conversion. ASU 2024-04 will become effective for the Company beginning October 1, 2026, and the Company is currently evaluating the impact on its consolidated financial statements and related disclosures. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, to improve its income tax disclosure requirements. Under the guidance, entities must annually (1) disclose specific categories in the rate reconciliation and (2) provide additional information for reconciling items that meet a quantitative threshold. This guidance became effective for the Company beginning on October 1, 2025. The Company is currently evaluating the impact of this new ASU on its financial statements and plans to adopt ASU 2023-09 on a prospective basis during this fiscal year.

Arrowhead Pharmaceuticals, Inc. and its subsidiaries (referred to herein collectively as the “Company”) are primarily engaged in developing medicines that treat intractable diseases by silencing the genes that cause them. Using a broad portfolio of RNA chemistries and efficient modes of delivery, the Company’s therapies trigger the RNA interference mechanism to induce rapid, deep and durable knockdown of target genes. RNA interference (“RNAi”) is a mechanism present in living cells that inhibits the expression of a specific gene, thereby affecting the production of a specific protein. The Company’s RNAi-based therapeutics may leverage this natural pathway of gene silencing to target and shut down specific disease-causing genes.

REDEMPLO® (plozasiran) is approved by the U.S. Food and Drug Administration (“FDA”) as an adjunct to diet to reduce triglycerides for adults with Familial Chylomicronemia Syndrome (“FCS”). REDEMPLO is also approved by the European Commission, Chinese National Medical Products Administration (“NMPA”), Health Canada, and the Australian Therapeutic Goods Administration (TGA) for the same indication.

REDEMPLO is a small interfering RNA (“siRNA”) therapeutic designed to suppress the production of apolipoprotein C-III (APOC3), a protein produced in the liver that raises triglyceride levels by slowing their breakdown and clearance. By targeting the APOC3 gene with sustained silencing, REDEMPLO delivers significant reductions in triglyceride levels. REDEMPLO is the first and only FDA-approved siRNA treatment studied in both genetically confirmed and clinically diagnosed patients living with FCS.

The interim Consolidated Financial Statements include the accounts of Arrowhead Pharmaceuticals, Inc. and its subsidiaries (wholly-owned subsidiaries and a variable interest entity for which the Company is the primary beneficiary). Wholly-owned subsidiaries refer to Arrowhead Madison, Inc., Arrowhead Australia Pty Ltd., Arrowhead Pharmaceuticals Ireland Limited and Arrowhead Pharmaceuticals NZ Limited. The Company’s variable interest entity is Visirna Therapeutics, Inc. (“Visirna”). For subsidiaries in which the Company owns or is exposed to less than 100% of the economics, the Company records net loss attributable to noncontrolling interests in its consolidated statements of operations equal to the percentage of the economic or ownership interests retained in such entity by the respective noncontrolling party.

The interim Consolidated Financial Statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”). The financial data of the Company included herein are unaudited. In the opinion of management, all material adjustments of a normal recurring nature have been made to present fairly the Company’s financial position as of June 30, 2026 and the results of operations and cash flows for the periods presented. All intercompany transactions and balances have been eliminated. Certain prior period amounts have been reclassified to conform with the current period presentation.

Certain financial information that is normally included in annual financial statements prepared in accordance with GAAP, but that is not required for interim reporting purposes, has been omitted from the accompanying interim consolidated financial statements and related notes. Readers are urged to review the Company’s Annual Report on Form 10-K for the fiscal year ended September 30, 2025 for more complete descriptions and discussions. Operating results and cash flows for the nine months ended June 30, 2026 are not necessarily indicative of the results that may be expected for the fiscal year ending September 30, 2026.

The Company operates as a single segment as the chief operating decision maker (“CODM”), reviews operating results on an aggregate basis and manages the operations as a single operating segment. Refer to Note 16, Segment Information, for further details on the segment information.

The Company’s primary sources of financing have been through the sale of its equity securities, credit facility, revenue from its licensing and collaboration agreements, the sale of certain future royalties and issuance of convertible debt. Research and development activities have required significant investment since the Company’s inception and are expected to continue to require significant cash expenditure in the future, particularly as the Company’s pipeline of drug candidates and its headcount have both expanded. Additionally, significant investment will be required as a growing commercial-stage Company and as the Company’s pipeline matures into later stage clinical trials.

As of June 30, 2026, the Company had $54.8 million in cash, cash equivalents and restricted cash ($4.1 million in restricted cash) and $1,547.2 million in available-for-sale securities to fund operations.

In total, the Company is eligible to receive up to $16.2 billion in additional developmental, regulatory and sales milestones based on programs that have been partnered, and may receive various royalties on net sales from its licensing and collaboration agreements, subject to the terms and conditions of those agreements.

There have been no changes to the significant accounting policies disclosed in the Company’s most recent Annual Report on Form 10-K for the fiscal year ended September 30, 2025, other than below:

The Company accounts for investments over which it has significant influence but not control under the equity method. The investment is initially recorded at cost and subsequently adjusted for the Company’s proportionate share of the investee’s net income or loss and are included in other assets in the accompanying consolidated balance sheets. The Company presents income or losses from equity investments as loss on equity method investment on the consolidated statements of operations and comprehensive (loss) income. If the share of losses exceeds the carrying value of the Company’s investment, the Company will suspend recognizing additional losses and will continue to do so unless it commits to providing additional funding or commits to guarantee investee liabilities. As of June 30, 2026, the Company had an equity method investment in Bisirna Therapeutics, Inc. (“Bisirna”). Refer to Note 8, Equity Method Investment, for further details.

The Company accounts for its convertible debt instrument as a single unit of accounting, classified as a liability, as the conversion features do not require bifurcation as a derivative under ASC 815-15 and the convertible debt instrument was not issued at a substantial premium. The Company records debt issuance costs as contra-liabilities in the consolidated balance sheets at issuance, and amortizes them over the contractual term of the convertible debt instrument based on the effective interest method.

The balance of the convertible notes presented in the consolidated balance sheets represents the principal balance of the convertible debt instrument less the unamortized portion of the debt issuance costs.

In July 2025, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) 2025-05, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable

and Contract Asset. This ASU allows companies to elect a practical expedient to assume that conditions as of the balance sheet date will remain unchanged for the remaining life of the asset when estimating the expected credit losses of the asset. The ASU will become effective for the Company beginning October 1, 2026, and the Company is currently evaluating the impact on its consolidated financial statements and related disclosures.

In January 2025, the FASB issued ASU 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses, in November 2024, and ASU 2025-01, Clarifying the Effective Date. These updates require entities to provide disaggregated disclosures of income statement expenses. The ASUs do not affect the expense captions presented on the face of the income statement but instead require the disaggregation of certain expense captions into specified categories within the footnotes to the financial statements. The ASUs will become effective for the Company beginning October 1, 2027, and the Company is currently evaluating the impact on its consolidated financial statements and related disclosures.

In November 2024, the FASB issued ASU 2024-04, Debt-Debt with Conversion and Other Options (Subtopic 470-20), which clarifies the requirements for determining whether certain settlements of convertible debt instruments should be accounted for as an induced conversion. ASU 2024-04 will become effective for the Company beginning October 1, 2026, and the Company is currently evaluating the impact on its consolidated financial statements and related disclosures.