In August 2020, we entered into a co-development agreement, referred to as the Development Funding Agreement, with BXLS V Bodyguard – PCP L.P. and BXLS Family Investment Partnership V – ESC L.P., collectively referred to as Blackstone Life Sciences, pursuant to which Blackstone Life Sciences will provide up to $150.0 million in funding for the clinical

development of vutrisiran and zilebesiran, two of our cardiometabolic programs. As of December 31, 2025, Blackstone Life Sciences has provided $70.0 million to fund vutrisiran development costs related to the HELIOS-B Phase 3 clinical trial and $26.0 million to fund Phase 2 clinical trials of zilebesiran. Additionally, Blackstone Life Sciences is obligated to fund $18.0 million for the Phase 3 clinical trial of zilebesiran following a development milestone triggered in September 2025, of which $6.0 million has been provided as of December 31, 2025. The amount of funding ultimately provided by Blackstone Life Sciences for the Phase 3 clinical trial of zilebesiran is dependent on us achieving the remaining specified development milestones. As agreed between Blackstone Life Sciences and the Company, we retain sole responsibility for the development and commercialization of both vutrisiran and zilebesiran.

As consideration for Blackstone Life Sciences’ funding for vutrisiran clinical development costs, we agreed to pay Blackstone Life Sciences $175.0 million triggered upon obtaining regulatory approval of vutrisiran for ATTR amyloidosis with cardiomyopathy, or ATTR-CM, and a 1% royalty on net sales of vutrisiran for a 10-year term beginning upon the first commercial sale following regulatory approval of vutrisiran for ATTR-CM. In March 2025, we obtained a regulatory approval from the FDA for vutrisiran for ATTR-CM, triggering the $175.0 million payable to Blackstone Life Sciences in eight equal quarterly payments over two years.

In September 2023, we announced positive topline results from the KARDIA-1 Phase 2 clinical trial of zilebesiran, triggering the achievement of the development milestone of $84.5 million payable to Blackstone Life Sciences in 16 equal quarterly payments over four years, as consideration for Blackstone Life Sciences’ funding for Phase 2 clinical development costs of zilebesiran. As consideration for funding for Phase 3 clinical development costs of zilebesiran, we agreed to pay Blackstone Life Sciences $243.0 million in 16 equal quarterly payments over four years triggered upon regulatory approval of zilebesiran in specified countries, unless it is later withdrawn from the market following a mandatory recall.

We and Blackstone Life Sciences each have the right to terminate the Development Funding Agreement in its entirety in the event of the other party’s bankruptcy or similar proceedings. We and Blackstone Life Sciences may each terminate the Development Funding Agreement in its entirety or with respect to either product in the event of an uncured material breach by the other party, or with respect to a product for certain patient health and safety reasons, or if regulatory approval in specified major market countries is not obtained for the product following the completion of clinical trials for the product. In addition, Blackstone Life Sciences has the right to terminate the Development Funding Agreement in its entirety upon the occurrence of certain events affecting our ability to make payments under the agreement or to develop or commercialize the products, or upon a change of control of us. Blackstone Life Sciences may also terminate the Development Funding Agreement with respect to a product if the joint steering committee elects to terminate the development program for that product in its entirety, if certain clinical endpoints are not achieved for that product or, with respect to vutrisiran only, if our right to develop or commercialize vutrisiran is enjoined in a specified major market as a result of an alleged patent infringement. In certain termination circumstances, we will be obligated to pay Blackstone Life Sciences an amount that is equal to, or a multiplier of, the development funding received from Blackstone Life Sciences, and we may remain obligated under certain circumstances to make the payments to Blackstone Life Sciences described above should we obtain regulatory approval for zilebesiran following termination.

We previously accounted for the Development Funding Agreement under ASC 815 as a derivative liability measured at fair value because it did not meet any of the derivative scope exceptions. In the fourth quarter of 2025, we adopted ASU 2025-07 on a modified retrospective basis as of January 1, 2025, which codified a new scope exception to the guidance of ASC 815. Refer to Note 2, Summary of Significant Accounting Policies, for further information related to the impact of adoption. We determined the underlyings in the Development Funding Agreement now qualify for this new scope exception and, as a result, are no longer accounted for under ASC 815. Beginning on the date of adoption of ASU 2025-07, or January 1, 2025, we record the proceeds received from Blackstone Life Sciences as debt obligations, net of closing costs, on our consolidated balance sheet due to our continuing involvement and obligation to repay Blackstone Life Sciences. We recognized $271.5 million as a cumulative effect adjustment to accumulated deficit as of January 1, 2025 as a result of the removal of the development derivative liability and establishment of new debt obligations.

The debt obligations to repay Blackstone Life Sciences for the vutrisiran and zilebesiran funding are accreted from the initial carrying amount to the total payment amount using the effective interest rate method over the life of the Development Funding Agreement. The effective interest rate is determined based on the proceeds received and projections of the amounts and timing of the future cash flows. The accretion is recorded as interest expense in the consolidated statement of operations and comprehensive income (loss). We recognize the proceeds received and the principal portion of payments made to Blackstone Life Sciences as financing activities within the consolidated statement of cash flows. As of December 31, 2025, our estimate of total interest expense resulted in an effective annual interest rate of 46% related to vutrisiran and 32% related to zilebesiran.

As payments are made to Blackstone Life Sciences, the balance of the liabilities is effectively repaid over the life of the Development Funding Agreement. The exact timing and amount of repayment is likely to change each reporting period. A significant increase or decrease in vutrisiran global net product revenues will materially impact the liability related to the vutrisiran payments and interest expense recognized. At each balance sheet date, we assess the expected payments to Blackstone Life Sciences and we prospectively adjust the amortization of the liabilities and the related interest expense.

As of December 31, 2024, the zilebesiran and vutrisiran funding obligations were accounted for as a derivative liability. We recorded $93.8 million within development derivative liability and $393.1 million within development derivative liability, net of current portion on our consolidated balance sheet. The change in fair value due to the remeasurement of the development derivative liability was recorded within other income (expense), net on our consolidated statements of operations and comprehensive income (loss) for the years ended December 31, 2024 and 2023.

As of December 31, 2024, the development derivative liability was classified as a Level 3 financial liability in the fair value hierarchy. The valuation method incorporated certain unobservable Level 3 key inputs including (i) the probability and timing of achieving stated development milestones to receive payments from Blackstone Life Sciences, (ii) the probability and timing of achieving regulatory approval and payments to Blackstone Life Sciences, (iii) an estimate of the amount and timing of the royalty payable on net sales of vutrisiran, assuming regulatory approval for ATTR-CM, (iv) our cost of borrowing (10%), and (v) Blackstone Life Sciences’ cost of borrowing (7%).

percentage of royalties payable, or the Royalty Interest, initially set at 50% with respect to net sales by MDCO, its affiliates or sublicensees of inclisiran (or the branded drug product, Leqvio) and any other licensed products under the MDCO License Agreement, and 75% of the commercial milestone payments payable under the MDCO License Agreement, together with the Royalty Interest, the Purchased Interest. If Blackstone Royalties does not receive payments in respect to the Royalty Interest by December 31, 2029, equaling at least $1.00 billion, Blackstone Royalties will receive the Royalty Interest at 55% beginning on January 1, 2030. In consideration for the sale of the Purchased Interest, Blackstone Royalties paid us $1.00 billion.

Due to our continuing involvement and an obligation to repay Blackstone Royalties, we recorded the proceeds from this transaction as a debt, net of closing costs, on our consolidated balance sheets. The debt obligations to repay the Purchased Interest are accreted from the initial carrying amount to the total payment amount using the effective interest rate method over the life of the Purchase Agreement. The effective interest rate is determined based on the proceeds received and projections of the amounts and timing of the future cash flows. The accretion is recorded as interest expense in the consolidated statements of operations and comprehensive income (loss). As of December 31, 2025 and 2024, our estimate of this total interest expense resulted in an effective annual interest rate of 10% and 10%, respectively. These estimates contain assumptions that impact both the amount recorded at execution and the interest expense that will be recognized in future periods. We account for any royalties and commercial milestones due to us under the MDCO License Agreement as revenue on our consolidated statements of operations and comprehensive income (loss).

As payments are made to Blackstone Royalties, the balance of the liability is effectively repaid over the life of the Purchase Agreement. The exact timing and amount of repayment is likely to change each reporting period. A significant increase or decrease in Leqvio global net revenue will materially impact the liability, interest expense and the time period for repayment. At each balance sheet date, we assess the expected payments to Blackstone Royalties and we prospectively adjust the amortization of the liability and the related interest expense.

As of December 31, 2025 and 2024, the carrying value of the liability was $1.48 billion and $1.45 billion, net of closing costs of $8.3 million and $9.1 million, respectively. The carrying value of the liability approximates fair value as of December 31, 2025 and is based on our current estimates of future royalties expected to be paid to Blackstone Royalties over the life of the arrangement, which is considered a Level 3 input.

As of December 31, 2025 and 2024, we recorded $118.8 million and $112.1 million, respectively, within liabilities related to the sale of future royalties and development funding and $1.36 billion and $1.34 billion, respectively, within liabilities related to the sale of future royalties and development funding, net of current portion related to the Purchased Interest.