Sarepta Therapeutics said it has sold 9.3 million shares of Arrowhead Pharmaceuticals in a privately negotiated block trade, generating at least $174 million in gross proceeds and eliminating its equity stake in the RNA-i drug maker. The divestiture coincides with the first clinical milestone in the companies’ small-interfering RNA collaboration: a safety review and enrollment threshold in the Phase 1/2 trial of SRP-1003 (also known as ARO-DM1) for type 1 myotonic dystrophy. The achievement triggers a $100 million payment from Sarepta to Arrowhead. Under a separate agreement, Arrowhead will receive roughly half the milestone—$50 million—in cash and the balance through the transfer and immediate redemption of 2.66 million of its own shares previously held by Sarepta. The buyback will reduce Arrowhead’s outstanding share count, while Sarepta applies the sale proceeds toward funding the milestone. Sarepta said it remains committed to the siRNA platform and plans to release preliminary data from the SRP-1003 study in the second half of 2025. Arrowhead said the combined cash and share reduction bolsters its balance sheet, which it expects to support operations into fiscal 2028.