Dyne Therapeutics, Inc. (DYN) SEC Filings, Jul-Aug 2026

A shareholder associated with DYN, John Cox, filed to sell up to 4,986 shares of common stock through Stifel Nicolaus & Company on or after August 13, 2026 on Nasdaq, with an indicated market value of $131,034.00. The issuer reported 186,746,431 shares of common stock outstanding. Cox acquired 11,250 shares on August 12, 2026 via Restricted Stock Units as equity compensation from the issuer. Over the prior three months, he sold 2,683 shares of common stock on June 16, 2026 for $49,191.00.

DYN reports a planned sale of 1,797 shares of common stock, with an indicated aggregate market value of $47,226.00, to be executed on or after August 13, 2026 on Nasdaq. The shares relate to equity compensation, including 4,062 shares tied to restricted stock units dated August 12, 2026.

The filing also lists prior activity over the past three months: on June 25, 2026, Erick Lucera is shown as having sold 2,362 shares of common stock for proceeds of $48,103.00. The notice provides advance disclosure of these intended and recent transactions.

Doug Kerr filed to sell up to 2,443 shares of DYN common stock through Stifel Nicolaus, with an indicated value of $64,203.00, in a transaction dated August 13, 2026 on Nasdaq. The filing references equity compensation awards of 5,312 and 3,000 restricted stock units and notes a prior sale of 887 shares for $16,263.00 on June 16, 2026.

Dyne Therapeutics, Inc. common stock is reported as beneficially owned by several affiliated Atlas Venture funds and associated entities in this amended Schedule 13G. Atlas Venture Fund XI and its related entities report beneficial ownership of 4,479,449 shares, the Opportunity Fund I entities report 975,931 shares, and the Opportunity Fund II entities report 1,344,719 shares of common stock. Based on 186,746,431 shares outstanding as of July 24, 2026, the filing states that the Fund XI entities each may be deemed to own 2.4% of the class, the Opportunity Fund entities 0.5%, and the Opportunity Fund II entities 0.7%. Collectively, the reporting persons may be deemed to beneficially own 6,800,099 shares, or 3.6% of the company’s outstanding common stock, while each reporting group indicates ownership of 5% or less of the class.

Janus Henderson Group Ltd. filed an amended beneficial ownership report stating that its affiliated asset managers may be deemed to beneficially own 11,997,738 shares of Dyne Therapeutics Inc. common stock, representing 7.3% of the class as of June 30, 2026. These shares are held in various client accounts referred to as Managed Portfolios, for which the asset managers exercise shared voting and dispositive power over all 11,997,738 shares, with no sole voting or dispositive power. The Managed Portfolios, not Janus Henderson, have the right to receive dividends and sale proceeds, and none of the individual portfolios owns more than five percent of Dyne Therapeutics’ common stock.

FMR LLC filed an amended beneficial ownership report for Dyne Therapeutics Inc. common stock. FMR LLC reports beneficial ownership of 11,206,999.89 shares, representing 6.8% of the outstanding common stock as of June 30, 2026. FMR LLC has sole voting power over 11,206,231.00 shares and sole dispositive power over 11,206,999.89 shares, with no shared voting or dispositive power.

Abigail P. Johnson is reported as having sole dispositive power over the same 11,206,999.89 shares, with no voting or shared powers. One or more other persons have rights to receive dividends or sale proceeds from these securities, but no such person holds an interest exceeding five percent of Dyne Therapeutics’ common stock.

Dyne Therapeutics reported second quarter 2026 results and detailed progress across its neuromuscular pipeline. The FDA accepted the Biologics License Application for z-rostudirsen in exon 51 Duchenne muscular dystrophy with Priority Review, setting a PDUFA target action date of January 21, 2027, and a global confirmatory Phase 3 FORZETTO trial is underway. In myotonic dystrophy type 1, Dyne completed enrollment of 71 participants in the registrational expansion cohort of the ACHIEVE trial for z-basivarsen, began dosing in the Phase 3 HARMONIA trial, and plans ACHIEVE topline data in the first quarter of 2027. The FDA also cleared an Investigational New Drug application for DYNE-302 in facioscapulohumeral muscular dystrophy. Financing actions included expanding a senior secured term loan facility with Hercules Capital to up to $400 million and completing an underwritten public offering of 21,045,000 shares at $20.50 per share for gross proceeds of approximately $431 million, supporting an expected cash runway into the second quarter of 2028.

Cash, cash equivalents and marketable securities were $898.5 million as of June 30, 2026, before the estimated $405.0 million of net proceeds from the July 2026 offering. Research and development expenses were $152.2 million and general and administrative expenses were $29.5 million for the quarter, compared with $99.2 million and $16.6 million, respectively, a year earlier. Net loss was $178.6 million, or $1.08 per basic and diluted share, versus $110.9 million, or $0.97 per share, for the prior-year quarter.

Dyne Therapeutics director Dirk Kersten, through ForDyne B.V., reported two indirect open-market sales totaling 261,460 shares of common stock on July 27, 2026, at weighted average prices of $25.5024 and $26.0428 per share. These trades were executed under a Rule 10b5-1 trading plan adopted by ForDyne on November 11, 2025. ForDyne is jointly owned by Forbion funds, and Kersten disclaims beneficial ownership of the shares except to the extent of his pecuniary interest.