Casey Safreno has resigned as global co-head of healthcare at Merrill Lynch to join Lehman Brothers, becoming the latest in a string of senior Merrill bankers to depart in the past few weeks.

A spokeswoman for Merrill confirmed that Safreno, based in the US, resigned last week. He was co-head of the healthcare group alongside Richard Girling, who is based in London. The spokeswoman was unable to comment on Safreno's replacement.