Brian Thompson, the CEO of UnitedHealth's (UNH.N), opens new tab insurance unit, was killed on Wednesday morning outside a Midtown Manhattan hotel in what police described as a targeted attack by a gunman lying in wait for him. Thompson, 50, was shot around 6:45 a.m. ET (1145 GMT) outside the Hilton on Sixth Avenue, just before the company's annual investor conference. He was rushed to a nearby hospital, where he was pronounced dead. Police said the gunman was at large and they...