Well-regarded for its ability to handle the ‘most complex and high-stakes merger control matters with precision and creativity’, Cleary Gottlieb Steen & Hamilton confirms its status as a market-leading outfit in merger control work, advising clients throughout the full lifecycle, from clearance strategy and second requests through to litigation. Cross-border coordination is a hallmark of the firm’s approach, with the US team regularly working alongside European colleagues on transactions subject to parallel review. The practice is jointly steered by Leah Brannon and Heather Nyong’o, with Brannon bringing extensive experience in global merger clearance, and San-Francisco based Nyong’o focused on US enforcement-facing work. Elsewhere in the team, Silicon Valley-based Brian Byrne and Daniel Culley play central roles on cross-border transactions, regularly coordinating US strategy with European colleagues on parallel reviews. Longstanding figure in the field George Cary, who splits his time between DC and San Francisco, remains closely involved in complex merger challenges, while David Gelfand is frequently called on when matters escalate into litigation. Bruce Hoffman advises clients drawing on his experience as former Director of the FTC’s Bureau of Competition, particularly in regulated sectors, and Kenneth Reinker remains a key port of call for clients operating in the pharma, healthcare, high-technology, media and finance sectors. Elaine Ewing advises on merger review and wider antitrust matters in the US and internationally, while New York-based Puja Patel focuses on merger control strategy, including second requests and cross-border filings, alongside antitrust litigation. Attorneys are based in Washington DC unless otherwise stated.
Legal 500 Editorial commentary
Testimonials
Collated independently by Legal 500 research team.
- 'Joe Kay, Chris Cook, and Jeremy Calsyn lead with exceptional strategic insight, ensuring clients receive clear, actionable guidance even under intense scrutiny.'
- 'Compared to other firms, this group stands out for its ability to anticipate regulatory concerns early and craft innovative solutions that keep transactions on track. Their collaborative approach and commitment to diversity and inclusion further strengthen their ability to deliver exceptional results across borders.’
- ‘Their ability to understand the deal (which is often complex in pharma and heavily scientific) is incredible. They are always two steps ahead of the game. Their experience in the pharma sector and with our company historically makes them extremely trustworthy and able to provide effective counsel.’
- ‘Kenneth Reinker - he just gets it. No other way to say it. He can talk to scientists, business people, anyone, and understand and pick up what they are saying easily. He understands the industry, landscape, our business, and fits in to deals seamlessly.’
- ‘This practice group is composed of excellent lawyers that help their clients drive a very complex practice before the FTC. I highly recommend them, led by Brian Byrne, this is the team that you should always engage for any antitrust filing you need to make.’
- ‘What stands out about this practice is its ability to handle the most complex and high-stakes merger control matters with precision and creativity. The team combines deep knowledge of global antitrust regimes with practical experience navigating multi-jurisdictional reviews and regulatory challenges.'
Key clients
- Somnigroup International (formerly Tempur Sealy International)
- Capital One
- Synopsys
- T-Mobile
- GTCR
- OCI N.V.
- Edwards Lifesciences
- Keurig Dr. Pepper
- RTX Corporation
- Alimentation Couche Tard
- Johnson Controls International
Work highlights
Represented Tempur Sealy in defeating a landmark vertical merger challenge brought by the FTC to Tempur Sealy’s $5 billion acquisition of Mattress Firm Group, the mattress retailer.
Advised Synopsys on its $35 billion acquisition of ANSYS.
Advised GTCR BC Holdings LLC in defeating the FTC’s lawsuit challenging its $627 million acquisition of Surmodics.
Lawyers
Hall of Fame
The lawyers at the very top of the profession, widely known and respected by peers and clients for their longstanding involvement in market-leading work.
Leading partners
The strongest partners in their field, leading on market-leading deals and endorsed by peers and clients alike.
Next Generation Partners
Junior partners with significant recognition from clients and peers in the market and key roles on multiple matters.
Practice head
Leah Brannon; Heather Nyong’o
Other key lawyers
George Cary; Bruce Hoffman; Brian Byrne; Elaine Ewing; David Gelfand; Daniel Culley; Ryan Shores; Puja Patel; Kenneth Reinker; Joe Kay; Chris Cook; Jeremy Calsyn; Ben Stievater.