Paul Scrivano, who a year ago took over as global head of M&A and private equity at O’Melveny & Myers, has left the firm for Ropes & Gray.

The Boston-based Am Law 100 firm, known for its corporate strength in advising private equity sponsors and key strategic acquirers in the pharmaceuticals sector like Pfizer Inc. and Shire Pharmaceuticals LLC, will see Scrivano become its new global head of M&A.