IONIS PHARMACEUTICALS INC New Standards Disclosure

Recent Accounting Standards

In November 2023, the Financial Accounting Standards Board, or FASB, issued Accounting Standard Update, or ASU, 2023-07, which provides updated guidance on segment reporting. The guidance requires public companies to disclose significant expenses that are regularly provided to the CODM, other segment items for each reportable segment and measures of segment profit or loss used by the CODM for allocating resources. In addition, the updated guidance requires public companies with a single reportable segment to provide all disclosures required under Accounting Standards Codification, or ASC, Topic 280, Segment Reporting, and public companies to include in interim reports all disclosures related to a reportable segment's profit or loss and assets that are currently required in annual reports. We adopted the annual reporting requirements in our 2024 Annual Report on Form 10-K and began providing the interim reporting requirements in our Quarterly Report on Form 10-Q in the first quarter of 2025. Refer to Note 12, Segment Information, for further details on our segment information.

In December 2023, the FASB issued ASU 2023-09, which provides updated guidance on income tax disclosures. The new guidance requires companies to provide additional disaggregation of information related to the income tax rate reconciliation and income tax payments. In addition, the guidance eliminates certain existing disclosure requirements related to uncertain tax positions and unrecognized deferred tax liabilities. This update is effective for annual periods beginning after December 15, 2024. We adopted this guidance on a prospective basis in our 2025 Annual Report on Form 10-K. This guidance did not have a material impact on our consolidated financial statements. Refer to Note 9, Income Taxes, for further details on our income taxes.

In November 2024, the FASB issued ASU 2024-03, which requires public companies to disclose disaggregated expenses for certain expenses in the income statement. This update is effective for annual periods beginning after December 15, 2026 and interim periods within annual periods beginning after December 15, 2027. Early adoption of this guidance is permitted. The guidance may be applied on a prospective or retrospective basis. We are currently assessing the impact and timing of adopting this update.

In November 2024, the FASB issued ASU 2024-04 to clarify the guidance for determining whether to account for early settlements of convertible debt as induced conversions or extinguishments. The amended guidance clarifies that the induced conversion accounting guidance under ASC Topic 470-20, Debt with Conversion and Other Options, is applicable to convertible debt instruments that are settled in equity, cash or other assets, or a combination thereof. Under the amended guidance, a settlement of a convertible debt instrument qualifies as an induced conversion if (i) the inducement offer includes all consideration (in form and amount) issuable under the conversion privileges defined in the terms of the convertible debt instrument, and (ii) the convertible debt instrument has a substantive conversion feature as of its issuance date and the inducement offer acceptance date. This update is effective for annual periods beginning after December 15, 2025 and interim periods within those annual periods. Early adoption of this guidance is permitted. The guidance may be applied on a prospective or retrospective basis. We early adopted this update in the fourth quarter of 2025 on a prospective basis and accounted for the partial repurchase of our 0% Notes due 2026 in accordance with the amended guidance. Refer to Note 7, Long-Term Obligations and Commitments, for further details on our convertible debt.

In July 2025, the FASB issued ASU 2025-05, which amended the guidance in ASC 326, Credit Losses, to simplify the estimation of credit losses on accounts receivable and contract assets from revenue transactions. The amended guidance 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. This update is effective for annual periods beginning after December 15, 2025 and interim periods within those annual periods. Early adoption of this guidance is permitted. Companies that elect the practical expedient are required to apply the amendments prospectively. We are currently assessing the impact and timing of adopting this update.

In September 2025, the FASB issued ASU 2025-06, which amended and simplified the existing guidance for software costs. The amended guidance removes references to software development stages and allows companies to begin capitalizing software costs when management has authorized and committed to funding the software project and it is probable that the project will be completed with the software performing the intended function. This update is effective for annual periods beginning after December 15, 2027 and interim periods within those annual periods. Early adoption of this guidance is permitted at the beginning of an annual reporting period. The guidance may be applied on a prospective or retrospective basis. We expect to early adopt this update in the first quarter of 2026 on a prospective basis. We expect this guidance will not have a material impact on our consolidated financial statements.

In September 2025, the FASB issued ASU 2025-07, which clarifies that share-based non-cash consideration received from a customer in exchange for goods or services under a revenue contract is subject to the guidance on non-cash consideration under ASC 606. This update is effective for annual periods beginning after December 15, 2026 and interim periods within those annual periods. Early adoption of this guidance is permitted. The guidance may be applied on a prospective or modified retrospective basis. We are currently assessing the impact and timing of adopting this update.

In December 2025, the FASB issued ASU 2025-11, which clarifies the current interim disclosure requirements and the applicability of ASC 270, Interim Reporting. The updated guidance does not change the fundamental nature or expand or reduce the disclosure requirements of interim reporting. This update is effective for interim reporting periods within annual reporting periods beginning after December 15, 2027. Early adoption of this guidance is permitted. We are currently assessing the impact and timing of adopting this update.

In December 2025, the FASB issued ASU 2025-12, which includes clarification and improvements to various topics in the ASC. This update is effective for annual reporting periods beginning after December 15, 2026 and interim periods within those annual periods. Early adoption of this guidance is permitted. We are currently assessing the impact and timing of adopting this update.

We do not expect any other recently issued accounting standards to have a material impact to our financial statements or disclosures.