Adi Rabinowitz, senior agency collateralized mortgage obligation structurer and trader at Bear Stearns, recently left the firm and plans to join J.P. Morgan, according to an official familiar with his move. At Morgan, Rabinowitz will run the new issue CMO business, the person said. Rabinowitz, reached on his cell phone, declined comment and Bill King, head of mortgage- and asset-backed trading at J.P. Morgan, did not return a call by press time.