Chrysler Corp. Vice Chairman Gerald Greenwald's resignation, announced at a time when the automaker is scaling back and struggling to regain lost market share, is troubling to the company and investors alike, analysts say. Greenwald, the apparent successor to Chairman Lee Iacocca, said Wednesday he was resigning to head United Air Lines employees' $4.38 billion proposal to buy the carrier. He became the third top Chrysler executive to quit this month. Iacocca, 65, whose contract expires at the end of 1991, said when Greenwald was named vice chairman in November 1988 that the chairmanship was his to lose. But Greenwald, 54, flew earlier this week to Iacocca's villa in central Italy to discuss his plans with his longtime boss, a company spokesman said. ``Lee made a major effort to try and change his mind,'' an unidentified company source told The Detroit News. But Iacocca and Greenwald returned Wednesday to Detroit to make the announcement. ``It has to disturb investors that ... the person who has been designated as the next chairman of Chrysler would leave Chrysler just a few days after the Chrysler treasurer announced his resignation,'' said Ronald A. Glantz, senior vice president at Dean Witter Reynolds Inc. in San Francisco. ``Not only will investors be disturbed by the management succession, they will wonder what these managers know about Chrysler that we don't know,'' Glantz said. Greenwald's resignation, effective immediately, follows those of Michael Hammes, who was vice president of international operations, and Chrysler Treasurer and Vice President Fred Zuckerman. Chrysler also has seen its market share slide and its earnings dive. The automaker reported a 80 percent drop in earnings during the first quarter of this year. It made $71 million during the period, or 32 cents a share, compared with $351 million, or $1.50 a share in the first quarter of 1989. Its U.S. market share for cars and light trucks fell from 14.1 percent at the end of April 1989 to 12.4 percent at the end of April 1990, and an austerity program launched last October will slice $1.5 billion from Chrysler's $426 billion annual budget by 1991. Greenwald, vice chairman since November 1988, will become chief executive officer of the Chicago-based United Employees Acquisition Corp., an entity formed by the airline's three major unions to handle the buyout efforts. UAL stock was up $4.75 a share to $155.62{ in mid-day trading on news of Greenwald's move. United's pilots union led an ill-fated $6.75 billion plan to acquire the airline last year. The proposal collapsed after the union and its partners, which included senior management and British Airways PLC, were unable to get bank financing for the deal, sparking a stock market panic. After the acquisition, Greenwald, 54, will become chairman and chief executive officer of UAL Corp. and United Airlines, its chief subsidiary, the employee group said in a statement. Glantz added that Greenwald is putting himself in position to cash in on the buyout. ``He's paid about $1 million a year (at Chrysler) ... but his Chrysler stock options are worthless,'' Glantz said. ``In a leveraged buyout that works, you can make tens of millions of dollars, maybe even hundreds of millions of dollars.'' Chrysler spokesman Steve Harris said there has been no decison on who will replace Greenwald, but Glantz said the logical successor is Robert S. Miller Jr., 49, now Chrysler's chief financial officer. United Auto Workers union vice president Stan Marshall, who leads the union's Chrysler department, speculated that Robert A. Lutz, president of the automaker's Chrysler Motors Corp. subsidiary, also will have a shot at filling Greenwald's shoes. ``He's been the one out there pushing the cars while Greenwald held back on putting cars on the market,'' Marshall said. Harris said the recent resignations were unrelated to each other or to the company's belt tightening. ``This really shows the depth of Chrysler's management,'' Harris said from the company's Highland Park headquarters. ``There are some very talented people here. They are sought after.'' Hammes left May 17 to become an executive vice president for Black & Decker Corp. and vice president of Black & Decker's power tool group, Harris said. Zuckerman said he resigned, effective this summer, to look elsewhere for a position in ``corporate restructuring or other senior financial officer activities.'' Greenwald worked with Iacocca at Ford Motor Co. and followed him to Chrysler in 1979. He played major roles in securing federal government loans that saved Chrysler from bankruptcy in 1979, and in negotiating the purchase of American Motors Corp. in 1987. ``I can understand Jerry's interest in an opportunity like the one United Air Lines presents today,'' Iacocca said. ``He is a major management talent, and he'll have a chance to show it.'' Greenwald said the difficult part about resigning from Chrysler will be leaving Iacocca and other Chrysler executives. ``Looking back, the most gratifying period for me were those uncertain years,'' he said. ``I've been offered an opportunity to lead another great company during a period of major transition, and it's an opportunity I can't turn down.''