Morgan Stanley Chief Financial Officer David Sidwell wasn't kidding last week when he said his firm is making progress in re-entering the private equity field - big time. On Tuesday, the firm said it has tapped Stephen Trevor, a star banker at Goldman Sachs, as co-head of the new business that is part of CEO John Mack's grand plan to enhance Morgan Stanley Investment Management. Trevor -- who reportedly will join the firm in March and for trivia buffs was a member of the U.S. Olympic fencing team in 1984 and 1988 -- will share duties with Alan Jones, a 20-year-MS leveraged-finance specialist and head of the firm's corporate finance department. The company also recently named managing director Mark Bradley to head its p.e.-focused financial sponsors group. Morgan Stanley appears set to make its return to the p.e. stage with a bang, according to Dow Jones Newswires, as it plans to launch a multi-billion fund with money from MS and institutional investors, and another billion-dollar baby in the new p.e. favorite field - infrastructure. MS left the private equity business two years ago because of complaints from clients that it was competing with them. It hopes to avoid such problems this time around, says DJN, by co-investing with clients.