Hercules Capital has expanded its senior secured term loan facility with Dyne Therapeutics to $400 million. Dyne drew $50 million at this close. It has now borrowed $200 million, with $200 million still available.
The second amendment, dated 16 June 2026 and announced the following day, added two $50 million tranches and increased the final tranche by $25 million. One of the new tranches was funded on execution. Of the remaining $200 million, $125 million is available subject to specified clinical, regulatory and commercial milestones and $75 million is subject to approval by the lenders' investment committee.
Drawn amounts bear a floating rate of the Wall Street Journal prime rate, subject to a 7.50 per cent floor, plus 2.45 per cent. Interest is payable monthly. Dyne may remain interest-only until 1 July 2029, a year later than under the previous terms, and that period may be extended to the 1 July 2030 maturity date if specified milestones are met. After the interest-only period, principal is repayable in equal monthly instalments, or in a single instalment if interest-only runs to maturity.
The original loan and security agreement, signed on 27 June 2025 and incorporated by the amendment, requires an end-of-term charge of 5.5 per cent of amounts borrowed, due at the earlier of prepayment or maturity. Hercules holds a first-priority security interest in substantially all of Dyne's property, including intellectual property.
The facility originated at up to $275 million, with $100 million funded at that close. A first amendment on 8 December 2025 permitted a further $50 million draw. This second amendment lifts the ceiling by $125 million.
Dyne Therapeutics is a Waltham, Massachusetts clinical-stage biotechnology company developing treatments for genetically driven neuromuscular diseases. It said the extra capacity supports its clinical programmes as it prepares for two potential US launches in the next two years.
Erick Lucera, Chief Financial Officer of Dyne Therapeutics, said: "This additional access to capital enhances our financial flexibility as we prepare for two potential U.S. launches in the next two years and continue on our mission to deliver functional improvement for individuals living with rare neuromuscular diseases."
R. Bryan Jadot, Senior Managing Director and Group Head at Hercules Capital, said: "Hercules is proud to be expanding our support of Dyne as they prepare for the potential approval and commercial launches of z-rostudirsen and z-basivarsen."
Hercules Capital, listed on the New York Stock Exchange, provides senior secured venture growth loans to technology and life sciences companies. The San Mateo firm said it has committed more than $27 billion to more than 700 companies since December 2003. In 2025 it reported $3.92 billion of new debt and equity commitments and $2.28 billion of gross fundings, and had about $5.7 billion of assets under management at 31 December 2025.