A deepening labor market downturn that cost 524,000 Americans their jobs last month is even swelling the jobless rate for chief executives.

William Watkins, ousted Monday at Seagate Technology LLC, is the sixth CEO of a publicly held company to be replaced in just the last eight days. His exit follows the departures last week of CEOs at Tyson Foods Inc., Borders Group Inc., Orbitz Worldwide Inc., Chico's FAS Inc. and Bebe Stores Inc.

Many experts view the changes as harbingers of significantly more turmoil in executive suites this year. Like other companies, these six corporations have been grappling with poor financial results, slumping stock prices and, in some cases, investor criticism.

An informal survey of management consultants, recruiters, investors and governance specialists pointed to several other CEOs whose jobs may be vulnerable: Rick Wagoner of General Motors Corp. ; Vikram Pandit of Citigroup Inc. ; Jonathan Schwartz of Sun Microsystems Inc. ; Steve Odland of Office Depot Inc.; and Kenneth Lewis of Bank of America Corp. Officials at those companies said their CEOs retain the board's support or declined to comment.

CEO turnover "doubles in bad times," said Dirk Jenter, an assistant finance professor at Stanford University's business school, who recently analyzed 1,627 CEO changes between 1993 and 2001. Mr. Jenter found that CEOs are most vulnerable in a downturn when their employers' shareholder returns lag rivals.