Up to $200,000,000

Common Stock

We previously entered into a Controlled Equity OfferingSM Sales Agreement, or the Sales Agreement, with Cantor Fitzgerald & Co., or Cantor, relating to shares of our common stock offered by this prospectus supplement and the accompanying base prospectus. In accordance with the terms of the Sales Agreement, pursuant to this prospectus supplement and the accompanying base prospectus, we may offer and sell shares of our common stock having an aggregate offering price of up to $200,000,000 from time to time through Cantor acting as our agent. As of the date of this prospectus supplement, we previously issued and sold under the Sales Agreement approximately 4.7 million shares of our common stock for aggregate net proceeds of $146.4 million pursuant to the prospectus supplement and accompanying base prospectus dated March 18, 2026. This prospectus supplement replaces and supersedes in its entirety the prior prospectus supplement and we will not make any further offers or sales of our common stock pursuant to the prior prospectus supplement following the date of this prospectus supplement.

Our common stock is traded on The Nasdaq Global Select Market under the symbol "STOK." The last reported sales price of our common stock on The Nasdaq Global Select Market on July 31, 2026 was $28.86 per share.

Sales of our common stock, if any, under this prospectus supplement may be made in sales deemed to be an "at the market offering" as defined in Rule 415(a)(4) promulgated under the Securities Act of 1933, as amended, or the Securities Act. Cantor is not required to sell any specific number or dollar amount of securities, but will act as a sales agent using commercially reasonable efforts consistent with its normal trading and sales practices, on mutually agreed terms between Cantor and us. There is no arrangement for funds to be received in any escrow, trust or similar arrangement.