A successful merger between T-Mobile and Sprint would create a 5G powerhouse and a U.S. telecommunications industry rival to market leaders AT&T Inc. and Verizon Communications Inc.

On Sunday, Sprint Corp. and T-Mobile US Inc. announced a merger that could transform the U.S. telecommunications sector. And more than a few lawyers from Am Law 100 firms are involved behind the scenes trying to smooth the way for a transaction not expected to close until the first half of 2019.

The proposed $26.5 billion all-stock deal will see Bellevue, Washington-based T-Mobile, which is owned by Deutsche Telekom AG, take control of Overland Park, Kansas-based Sprint, a majority stake of which is owned by Japanese conglomerate SoftBank Group Corp. If the merger receives shareholder and regulatory approval, the combined $146 billion company will create a U.S. telecommunications rival to industry leaders AT&T Inc. and Verizon Communications Inc.

A successful union between T-Mobile and Sprint will also narrow U.S. consumers' choices among large wireless carriers to three, instead of four. The number of lawyers advising on that process is significantly higher, somewhere in the multiple of dozens.

Wachtell, Lipton, Rosen & Katz, led by partners Adam Emmerich and David Lam, is advising T-Mobile and Deutsche Telekom. Other Wachtell lawyers working on the deal include finance partners Eric Rosof, Emil Kleinhaus and John Sobolewski; tax partners Jodi Schwartz and T. Eiko Stange; and executive compensation and benefits partner Andrea Wahlquist, the latter a rare lateral hire by the firm in 2014.

Cleary Gottlieb Steen & Hamilton, which previously advised Deutsche Telekom on its ultimately unsuccessful $39 billion sale of T-Mobile to AT&T a half-dozen years ago, is working with DLA Piper as regulatory counsel to the Bonn, Germany-based company. The Cleary Gottlieb antitrust team includes partners Mark Nelson, George Cary, Daniel Culley and Jeremy Calsyn.

Nancy Victory and Michael Senkowski, co-chairs of the global telecom practice at DLA Piper after joining the global legal giant in 2016 from Wiley Rein, are leading up a team from that firm that also includes technology transactions and telecom partners Eric DeSilva, Edward “Smitty” Smith and John Beahn, as well as government services transactional co-chairwoman Sarah Kahn. (Beahn joined DLA Piper earlier this year from Skadden, Arps, Slate, Meagher & Flom.)

Robert McDowell, another ex-Wiley Rein practice leader and former commissioner at the Federal Communications Commission who joined Cooley in late 2016, is serving as regulatory and public affairs counsel to T-Mobile. K&L Gates corporate partner Margaret Inouye, antitrust and litigation partner Christopher Wyant and technology transactions partner Mark Wittow are also advising T-Mobile.

Another group of lawyers from Latham & Watkins, led by partners Charles Ruck and Daniel Rees, is providing counsel to T-Mobile's committee of independent directors. Also on the Latham team are finance partners Keith Halverstam, Benjamin Cohen and Greg Robins; communications industry and communications law global chairmen James Barker and Matthew Brill; antitrust partner Michael Egge; partner Steven Croley on matters related to the Committee on Foreign Investment in the U.S. (CFIUS); executive committee member and partner Michele Johnson on compliance matters; and counsel David Kuiper on intellectual property transactional issues. (Ruck, who works out of New York and Southern California, is one of several Latham partners vying to replace William Voge as firm leader.)

Latham is also handling corporate, compensation and benefits, compliance, finance, regulatory and tax matters for T-Mobile related to its bid for Sprint. That work is being done by a team led by Latham partners James Gorton, Thomas Malone, Josh Dubofsky and Joel Trotter. Latham partners Laurence Seymour and Julie Crisp are counseling on compensation matters, with partners Jiyeon Lee-Lim and Matthew Dewitz providing tax advice. Latham antitrust partners Amanda Reeves and Farrell Malone, compliance partner James Brandt and finance partner Senet Bischoff are also working on the deal for T-Mobile.

New York-based investment banking firm Evercore Partners Inc., which is serving as financial adviser to the independent committee of T-Mobile directors, is being advised by Weil, Gotshal & Manges corporate chairman Michael Aiello and M&A partner Eoghan Keenan. The company's independent directors have tapped Richards, Layton & Finger to serve as Delaware counsel. The Goldman Sachs Group Inc., a financial adviser to T-Mobile and Deutsche Telekom, is being advised by Fried, Frank, Harris, Shriver & Jacobson M&A co-head Philip Richter and partner Warren de Wied.

Wilmer Cutler Pickering Hale and Dorr partner Jamie Gorelick and senior international counsel Robert Kimmitt, both of whom co-chair the firm's strategic response group, are also advising T-Mobile and Deutsche Telekom. Gorelick and partner Kenneth Salazar, a former U.S. senator from Colorado who joined Wilmer in 2013, are working for T-Mobile and its parent company on potential regulatory issues that may arise with state attorney generals' offices. Kimmitt is advising both entities on CFIUS matters. David Miller serves as general counsel for T-Mobile, while Deutsche Telekom's in-house legal chief is Claudia Junker.

Hogan Lovells partners Trey Hanbury, Ari Fitzgerald, Edith Ramirez and Tom Peters are also representing T-Mobile on its bid to receive certain regulatory approvals necessary to complete its purchase of Sprint. Ramirez, a former chair of the U.S. Federal Trade Commission, joined Hogan Lovells as a partner late last year.

Sprint is being advised by another team of lawyers from Morrison & Foerster. MoFo has long served as outside counsel to Tokyo-based SoftBank on transactional matters. Robert Townsend, chairman of MoFo's global M&A group, is leading a team from the firm advising Sprint that includes Tokyo managing partner and SoftBank dealmaker Kenneth Siegel; corporate partner Brandon Parris; corporate finance co-chairman David Slotkin; global finance co-chairman and national security co-head Nicholas Spiliotes; antitrust co-chairman Jeff Jaeckel; partner David Meyer; and tax partner Bernie Pistillo.

Other MoFo partners working on the deal are Michael O'Bryan, Scott Lesmes, Mark Wojciechowski, Ivan Smallwood, Michael Miller, Paul Jahn and Domnick Bozzetti.

Goodwin Procter partners Stuart Cable and Mark Opper are leading a team from that firm representing an independent transaction committee of Sprint's board of directors. The Goodwin Procter deal team includes partners Howard Cubell, Deborah Birnbach, Andrea Agathoklis Murino, Paul Jin, Caroline Bullerjahn and Richard Matheny. Potter Anderson & Corroon corporate partners Mark Morton and Pamela Millard are serving as Delaware counsel to the independent transaction committee.

Skadden is serving as regulatory co-counsel to Sprint with a team led by antitrust partners Steven Sunshine and Matthew Hendrickson. CFIUS head Ivan Schlager, partner Michael Leiter and counsel Malcolm Tuesley are handling CFIUS matters for Sprint, whose chief legal officer is Jorge Garcia. Skadden M&A partner Thomas Kennedy, executive compensation and benefits partner Regina Olshan and tax partner Steven Matays are also working on the deal.

Stephen Amdur, a corporate partner at Pillsbury Winthrop Shaw Pittman in New York who joined the firm late last year from Latham, is advising The Raine Group LLC in its role as financial adviser to Sprint. Simpson Thacher & Bartlett corporate partner Caroline Gottschalk is counseling J.P. Morgan Securities LLC in its role as financial adviser to Sprint. Another team from Sidley Austin, led by partners Martin Wellington and Jennifer Fitchen, is representing Centerview Partners LLC in its role as financial adviser to the independent transactions committee of Sprint's board of directors.

Cahill Gordon & Reindel corporate partners Adam Dworkin, Ariel Goldman, Timothy Howell, Marc Lashbrook and John Tripodoro are counseling Barclays plc, Credit Suisse AG, Deutsche Bank AG, Goldman Sachs, Morgan Stanley & Co. LLC and the Royal Bank of Canada in their roles providing debt financing for a future combination between Sprint and T-Mobile, although a final deal still remains a long way from completion.

T-Mobile's previous bid to sell itself to AT&T, which collapsed in late 2011 in the face of regulatory opposition, generated roles for at least a half-dozen outside firms. In subsequent years, many of those same firms have landed engagements on several key transactions in the telecom space, such as AT&T's $48.5 billion acquisition of DirecTV, AT&T's proposed $85.4 billion buy of Time Warner Inc., The Walt Disney Co.'s proposed $52.4 billion takeover bid for Twenty-First Century Fox Inc. and Verizon's purchases of AOL Inc. and Yahoo Inc.

Closing arguments began this week in the U.S. Department of Justice's suit seeking to block AT&T's deal with Time Warner.