Two UBS collateralized mortgage obligation traders have departed the firm and are headed to RBS Greenwich Capital. David Cannon joins as head of CMO trading, according to a market participant, and Cass Tokarski hops to RBS as a trader. Cannon, who was between jobs and on vacation last week, declined comment when reached on his cell phone; Tokarski did not return calls to his cell phone. Calls to UBS' desk were referred to Allison Chin-Leong, spokeswoman, who declined comment. Mark Kollar, spokesman for RBS, did not return calls by press time.