Lazard's ( LAX) decision to team up with corporate raider Carl Icahn is raising some eyebrows on Wall Street. Most notably, Rob Kindler, a top investment banker with J.P. Morgan Chase ( JPM), took issue Thursday with Lazard's representation of Icahn in his battle with Time Warner ( TWX). Kindler, J.P. Morgan's global head of mergers and acquisition, says he wonders whether Lazard will alienate some of its corporate clients by joining forces with Icahn, a trader who built his reputation on Wall Street by declaring war on the managers of Fortune 500 companies. "How do you build relationships with CEOs when you represent Icahn?'' says Kindler, one of the headline speakers during an all-day conference in New York on the outlook for M&A in 2006. Kindler said it is a decision that Bruce Wasserstein, Lazard's chairman and CEO, could come to regret. "I don't have a clue as to what Bruce was thinking,'' says Kindler of the well-known banker, whose brass-knuckles style of corporate deal-making in the 1980s earned him the nickname "Bid 'em Up Bruce." A Lazard spokesman declined to comment. Kindler says Wasserstein's deal with Icahn is particularly curious in light of the fact that the dealmaker's former firm, Wasserstein Perella, was an adviser on the 2000 merger between America Online and Time Warner. The investor group led by Ichan hired Lazard to "analyze various strategic alternatives'' for Time Warner and advise the group on planning for an upcoming proxy battle. In a press release earlier this week, Wasserstein said: "We look forward to working with the Icahn Group to help maximize value for all Time Warner shareholders.'' Ironically, Kindler's remarks came at conference sponsored by The Deal, a publication owned by a company controlled by Wasserstein. It's not uncommon for investment bankers to throw some sharp elbows at each other in angling for a deal. But it's not every day a banker takes a jab at the host of an event where he's speaking.