Rosemary G. Reilly

ROSEMARY REILLY is a seasoned corporate lawyer with more than 20 years of experience advising life sciences and technology companies on corporate and securities matters. She provides ongoing counsel for clients ranging from startups and emerging companies to mature public companies, and venture capital firms. Drawing on her experience as in-house counsel, she has a deep understanding of the legal and business challenges faced by her clients.

In addition to advising clients on a wide range of corporate and securities matters, Rosemary has significant experience with private and public securities offerings, mergers and acquisitions, joint ventures, strategic alliances, venture capital, strategic financings, and SEC compliance. She regularly advises boards in connection with securities transactions and general corporate matters, and provides advice on governance and commercial transactions. Rosemary also counsels emerging companies throughout their lifecycle and through complex transactions, including venture capital financings, initial public offerings, and acquisitions. She has a particular focus on the biotechnology, pharmaceutical, and life sciences sectors.

Rosemary’s experience includes serving as general counsel at Shoreline Communications, Inc. (now ShoreTel, Inc.), and later in the legal department of Wind River Systems, Inc. (previously NASDAQ: WIND).

Rosemary has been recognized in the 2025 edition of Chambers USA for Massachusetts Private Equity: Venture Capital Investment, with sources describing her as “rigorous in her thinking and willing to take very thorny problems and face them head on.” She has been selected by peers for inclusion in the 2019–2024 editions of The Best Lawyers in America® in the areas of Biotechnology and Life Sciences and was named a 2023 “Lawyer of the Year.” In 2020, Rosemary was shortlisted as “Venture Capital Attorney of the Year” by LMG Life Sciences, and was part of the team awarded one of five “Finance and Transactional Impact Cases of the Year” by LMG Life Sciences in 2017. Rosemary was selected as a “Top Women of Law” honoree by Massachusetts Lawyers Weekly in 2022.

Venture Capital, Private, and Public Financings

• Nuvalent Inc. in its US$575 million and its US$500 million public offerings.
• Orna Therapeutics in its US$221 million Series B financing.
• Astria Therapeutics, Inc. in its US$110 million PIPE.
• Georgiamune in its US$75 million Series A financing.
• Werewolf Therapeutics in its US$72 million Series B financing.
• Ribon Therapeutics in its US$65 million Series B financing.
• Twentyeight-Seven, Inc. in its US$65 million Series A financing.
• PAQ Therapeutics in its US$39 million Series B financing.

Initial Public Offerings

• Akouos, Inc.
• Astria Therapeutics, Inc.
• Editas Medicine, Inc.
• Epizyme, Inc.
• Nuvalent Inc.
• Stealth Biosciences, Inc.

M&A

• Astria Therapeutics, Inc.in its pending acquisition by BioCryst Pharmaceuticals.
• Akouos, Inc. in its acquisition by Lilly.
• CoStim Pharmaceuticals in its acquisition by Novartis.
• Mitobridge, Inc. in its acquisition by Novartis.
• Orna Therapeutics in its acquisition of ReNAgade Therapeutics.
• Potenza Therapeutics in its acquisition by Astellas Pharma.
• Viamet Pharmaceuticals in its acquisition by NovaQuest Capital.

The above matters were handled prior to joining Sidley.

• American Bar Association
• Boston Bar Association
• Massachusetts Bar Association