Allen & Overy's (A&O's) US antitrust head has left the firm's New York arm to join local rival Howrey.

Michael Jahnke joined the US firm this week (3 August) as a partner in its competition practice after seven years at the magic circle firm's US outpost.

Jahnke focuses on advising large corporates within the food, tobacco, energy and telecommunications sectors – regularly acting on M&A transactions in front of the Federal Trade Commission and the Department of Justice.

Most recently Jahnke advised Imperial Tobacco on antitrust matters following its $23bn (£13.5bn) takeover of Altadis at the beginning of last year.

Howrey antitrust co-chair Alan Wiseman said: "We are pleased that Michael has decided to bring his wealth of knowledge and expertise to our team in New York. He will complement the lawyers there, as well as the entire practice."

The loss marks the second high-profile departure from A&O's New York office this year, after former US co-head Daniel Cunningham defected to litigation boutique Quinn Emanuel Urquhart Oliver & Hedges' New York office in March following an eight-year stint at the magic circle firm.

A&O chose not to replace Cunnigham, with Kevin O'Shea taking full responsibility for the firm's US practice.