Ropes & Gray has added Filko Prugo as partner and chair of the firm's life sciences intellectual property litigation practice. He joins from O'Melveny & Myers, where he was partner and co-founder of that firm's Hatch-Waxman and BPCIA practice.

Loeb & Loeb has added Eve Costopolous as of counsel and Ryan Hagglund as senior counsel to the firm's multidisciplinary life sciences practice. Costopoulos was previously general counsel and chief compliance officer at Vyera Pharmaceuticals. Hagglund joins from Milbank, Tweed, Hadley & McCloy.

Arent Fox has added sports partner Jennifer Pogorelec O'Sullivan to the firm's New York office. Ms. O'Sullivan joins from Hand Baldachin & Amburgey, where she led the Sports and Entertainment practice group.

Stephen Sonnenberg has left Paul Hastings after 25 years to join JAMS.

Kai Haakon Liekefett has joined Sidley Austin as a partner in its M&A group and will lead the firm's shareholder activism practice. He was formerly with Vinson & Elkins.

Justin Ellis and Gerald Meyer have been named partners at MoloLamken.

Kristen A. Marotta has joined Fox Rothschild as an associate in the firm's Health Law Department. She was previously an associate at Nixon Peabody.