Davis Polk & Wardwell and Skadden Arps Slate Meagher & Flom have won lead roles on the biggest energy deal since 2006 – Exxon Mobil's acquisition of natural gas company XTO Energy for $31bn (£19bn).

Davis Polk, which represented Exxon on its $80bn (£49bn) purchase of Mobil in 1999, reprised its role as lead M&A counsel, with a team led by M&A head George Bason, alongside corporate partners Louis Goldberg and Arthur Golden, tax partner Avishai Shachar, benefits partner Edmond FitzGerald and environmental partner Gail Flesher.

A Skadden team led by partners Roger Aaron and Stephen Arcano, the head of the firm's New York M&A group, advised XTO, the largest US-based producer of natural gas. The team also included M&A partner Kenneth Wolff, executive compensation partner Stuart Alperin, antitrust partners Neal Stoll and Ian John, and tax partner David Rievman.

The deal will see XTO shareholders receive 0.7098 shares of Exxon Mobil for each share of XTO they own, while Exxon will also take on $10bn (£6.1bn) in debt.

Weil Gotshal & Manges and Covington & Burling will provide antitrust counsel to Exxon. The addition of Weil is notable as Covington has long been Exxon's go-to antitrust counsel, and the firm, led by partner Deborah Garza, guided Exxon through the antitrust process after its acquisition of Mobil.

Weil has a long history of representing Exxon in class action and intellectual property litigation.

This article first appeared on The Am Law Daily blog on americanlawyer.com.