Janus Henderson Group plc Increases Stake in Dyne Therapeutics Inc to 8.3%

Janus Henderson Group plc filed a Schedule 13G/A on May 15, 2026, reporting an 8.3% ownership stake in Dyne Therapeutics Inc (DYN). As of the event date on March 31, 2026, the filer beneficially owns 13,647,376 shares of common stock. This filing represents an increase from a previously reported 0.0% position, indicating a significant new accumulation or reporting threshold crossing. Janus Henderson Group plc acts as the parent holding company for several SEC-registered investment advisers, including Janus Henderson Investors US LLC and Janus Henderson Investors UK Limited, which exercise investment and voting discretion over managed portfolios. The filing clarifies that the shares are held in the ordinary course of business without the intent to influence or change the control of the issuer. All 13,647,376 shares are reported under shared voting and shared dispositive power. No individual managed portfolio under the parent company owns more than 5% of the outstanding common stock.