on its failed attempt to purchase Unocal before Chevron came in).

The Skadden squad includes Charles Mulaney, L. Byron Vance and Joseph Yaffe, as well as antitrust attorneys Neal Stoll and Ian John. Stoll and John both worked on a similar deal of an oil giant buying a shale gas producer, counseling XTO Energy Inc. on its $35 billion acquisition by Exxon Mobil Corp. last year.

Atlas received financial advice from Ralph Eads at Jefferies & Co. and Dan Ward, Greg Sommer and John Hanna at Deutsche Bank Securities Inc. Eads has been the king of the shale deals, having worked on Chesapeake Energy Corp.'s $1 billion sale of properties in the Eagle Ford to China's Cnooc and its $2.2 billion joint venture with Total SA in North Texas' Barnett Shale, along with other ventures with Plains Exploration & Production Co. in the Haynesville Shale and Statoil ASA in the Marcellus Shale. He also advised Plains on its $578 million purchase of properties in the Eagle Ford from Hughes Co.; Eagle Ford and Marcellus Shale operator East Resources Inc. on its $4.7 billion sale to Royal Dutch Shell plc; and Atlas on its previously signed $1.7 billion joint venture with Reliance Industries Ltd. in the Marcellus.

Ward has worked mostly on traditional oil and gas deals over the years, including advising Anadarko Petroleum Corp. on its $23 billion acquisition of Kerr-McGee Corp. and Western Gas Resources Inc. His ties to Atlas go deep: He worked with Atlas Energy Resources LLC, now part of Atlas, on its $1.225 billion acquisition of DTE Gas & Oil Co. from DTE Energy Co. in 2007.

Sommer recently joined Deutsche Bank from Citigroup Inc., while Hanna worked with Ward on advising Grey Wolf Inc. on its sale to Canada's Precision Drilling Trust a few years ago for $2 billion.

In Atlas' legal corner was Wachtell, Lipton, Rosen and Katz, whose team included David Lam, Mark Gordon, Adam Emmerich, Joshua Holmes, Michael Segal, Joshua Feltman and Jonathan Moses. Lam also worked on Atlas' joint venture with Reliance, as did Holmes, Feltman and Moses. He also played a role in the purchase by Atlas of the shares it did not already own of Atlas Energy Resources.

Atlas shareholders will also get 41 million units of Atlas Pipeline Holdings after restructuring transactions before the deal closes valued at $5.09 per Atlas share. Those deals include Atlas acquiring 49% of Laurel Mountain Midstream LLC from Atlas Pipeline Partners LP for $403 million and selling all interests in existing investment partnerships, 175 billion cubic feet of proved natural gas reserves and other energy assets to Atlas Pipeline for $250 million, including $30 million in cash and $220 million in newly issued units.

Another team of advisers worked on that piece. Berenson & Co.'s George Ward, John Rice, Dave Saxena, Steve Robbins and Adam Epstein advised Atlas Pipeline Partners on the Laurel Mountain sale, while Stifel, Nicolaus & Co.'s Chris Shebby and Friedman Kaplan Seiler & Adelman LLP's Gerald Adler and Barry Adelman assisted the special committee of the board of Atlas Pipeline Partners' general partner, Atlas Pipeline Partners GP LLC.