Howard Capek, a UBS analyst, has been forced to resign from the bank's New York office after warning a client about embattled health care firm, HealthSouth, during a quiet period when he was forbidden to publish research on the company.

A spokesman for UBS said: "As part of the bank's ongoing cooperation with regulators in connection with their investigation into HealthSouth, we have found an isolated incident in 1999 where the conduct of Capek violated UBS internal policies. When advised of these policies, Capek promptly resigned."