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Qualified in Texas (US), 2004
Partner for 19 years
Corporate M&A
Private Equity
Energy
Infrastructure
M. Breen Haire is a Partner at Simpson Thacher & Bartlett, based in the Houston office. As Co-Managing Partner and Co-Head of the Firm’s Energy and Infrastructure Practice, Breen specializes in mergers and acquisitions and private equity transactions, particularly within the infrastructure sector. His extensive experience spans energy, digital infrastructure, and transportation industries, representing major operating companies and investors. Breen's notable achievements include being named “2025 Dealmaker of the Year” by The American Lawyer. He holds a JD from New York University School of Law and a BFA from Boston University. Breen is recognized for his strategic acumen in high-stakes transactions and his commitment to client success.
Energy Transactions
Telecommunications and Technology
Investment Funds and Financial Services
Corporate Mergers and Acquisitions
Partner
2014 – Unknown
Partner
2004 – 2014
Associate
1999 – 2004