O'Melveny & Myers has promoted four partners to leadership roles in the wake of several recent high-profile departures from the firm, reports The Am Law Daily.

Silicon Valley partner Steven Tonsfeldt has been named as the new leader of the firm's M&A practice group, succeeding Ilan Nissan, who is joining Dewey & LeBoeuf along with M&A partner Chris Nugent.

Meanwhile, San Francisco partner Brophy Christensen and New York and Los Angeles partner Eric Reimer will take over the leadership of the corporate finance/capital markets group from Gregory Ezring, who joined Paul Weiss Rifkind Wharton & Garrison in May.

In addition, Washington DC partner Robert Rizzi is moving into the tax leadership position formerly held by Brad Okun, who also joined Paul Weiss in May.

"These new appointments, which include leadership roles for our two largest transactions practice groups, give us the opportunity to inject some fresh perspectives as we build our transactions platform going forward," said firm chairman Arthur Culvahouse.

The promotions come on the heels of a number of high-profile partner losses for O'Melveny. Other departures since the beginning of the year include former Federal Trade Commission head Timothy Muris, who joined Kirkland & Ellis alongside two antitrust partners in late March, and another seven partners, in addition to Okun and Ezring, who left O'Melveny in early May for Paul Weiss and Weil Gotshal.

The recent moves continue the steady losses of partners that came to the firm as a result of O'Melveny's 2002 acquisition of O'Sullivan Graev & Karabell, a New York-based private equity boutique. Nissan, Nugent, Ezring and Okun all were O'Sullivan alumni.

The Am Law Daily is a US affiliate title of Legal Week.