The finance chief at Fortelus Capital Management LLP got an alarming phone call just as he was getting ready to leave work on a Friday. The caller said he was from Coutts, the London-based hedge fund’s bank, and warned there may have been fraudulent activity on the account. Fortelus Chief Financial Officer Thomas Meston was reluctant, but agreed to use the bank’s smart card security system to generate codes for the caller to cancel 15 suspicious payments. He hung up just after 6 p.m., according to court filing.