
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

- KKR and PSP Investments acquired the target/assets from American Electric Power in a acquisition on not available. - Deal value was 2820000000 Sector: Energy; Location: USA. - On the acquirer side, not available advised, led by Breen Haire, Shamus Crosby, Mark Kunzman, Aaron King, Andrew Kingsbury, Gavin Jaco, Craig Wickham, Kaitlyn Greening, Brian Steinhardt, Brandon Barton, Nancy Mehlman, Lina Pan, Michael Stephenson, David Rubinsky, Miles Jasper, Alisa Tschorke, Lori Lesser, Christina Breitbeil, Dennis Loiacono, Peter Guryan, Jamie Logie.
Sep 01 2025
3B
Private Equity
Partner
2014 – Unknown
Partner
2004 – 2014
Associate
1999 – 2004

- I Squared acquired the target/assets from WhiteWater in a m&a on 2025-07-05. - Deal value was 55000000000 (source: AI Estimation) Ownership: minority stake; Sector: Energy; Location: USA. - Acquirer-side legal counsel was not specified.
Jul 05 2025
2B
M&A
1 min
JD, New York University School of Law
1999
BFA, Boston University
1994