By David Thomas

Oct 2 (Reuters) - The largest-ever buyout in the U.S. rail sector and the largest leveraged buyout in history helped propel Wachtell, Lipton, Rosen & Katz to the top of the London Stock Exchange Group's rankings of principal M&A legal advisers.

New York-based Wachtell was the top principal adviser by deal value in LSEG's rankings for the first nine months of 2025, working on 75 global announced deals worth a combined $461 billion.

Two of the firm's largest deals of the year were announced last quarter. Wachtell is serving as the legal adviser to Norfolk Southern NSC.N in its $85 billion acquisition by Union Pacific UNP.N to create the first U.S. coast-to-coast freight rail operator.

The law firm is also representing Electronic Arts EA.O in the video game developer's sale to Saudi Arabia's Public Investment Fund, Jared Kushner's Affinity Partners and private equity firm Silver Lake in a $55 billion cash and debt deal.

Partners at Wachtell did not immediately respond to requests for comment.

Worldwide M&A activity hit $3 trillion during the first nine months of the year, a 33% increase compared to the same period last year, LSEG found. But the volume of deals continues to drop — nearly 37,000 deals were announced, a 7% decrease compared to the same period last year.

LSEG called 2025 so far the strongest period ever recorded for "mega deals" — transactions worth more than $10 billion.

Boston-founded Goodwin Procter took the No. 1 principal adviser spot by number of transactions in LSEG's data, working on 647 deals worth $110.7 billion so far this year.

Latham & Watkins topped the rankings among firms advising any party in a transaction by value, working on 592 deals worth more than $489 billion.

Paul Kukish, a global co-chair of Latham's M&A and private equity practice, touted Latham's work in an email and said he expected the dealmaking environment to remain strong.

"In a year that started off a little slower than may have been expected, we are now at a M&A peak," Kukish said.

Like Wachtell, Latham is also involved in the EA deal to take maker of the "Battlefield" and "Madden NFL" series private. The firm said it is serving as primary legal counsel to Silver Lake.

Wachtell and Latham are also serving as legal advisers to Charter Communications CHTR.O and Cox Communications, respectively, in Charter's $34.5 billion acquisition of privately held Cox.

(Reporting by David Thomas)