-- General Motors Corp. chief executive G. Richard Wagoner Jr. told employees Thursday that the world's largest automaker has no plans to file for bankruptcy protection despite heavy losses in its North American division and the threat of a strike at Delphi Corp., its major supplier.

"I'd like to just set the record straight here and now: there is absolutely no plan, strategy or intention for GM to file for bankruptcy," Wagoner wrote in a letter to employees, which a GM spokesman said was posted on an internal Web site.

Wagoner said GM has a clearly defined turnaround plan and "a robust balance sheet," with $19 billion in cash and $16 billion in assets in a trust fund for retiree health care.

"The large losses at GM North America are unsustainable, for sure, and require a comprehensive strategy to address them . . . a strategy that must be implemented promptly and effectively, to get our U.S. business profitable again," Wagoner said.

GM shares rose $1.34, or 6.3 percent, to close at $22.63 on the New York Stock Exchange. They had traded at an 18-year low of $20.90 during Wednesday's session and slipped as low as $20.60 in Thursday's trading before Wagoner's letter was posted.

Standard & Poor's Ratings Services upgraded its opinion of GM's stock Thursday from "strong sell" to "hold," saying it doesn't expect the company to file for bankruptcy in the next 12 months. S&P said it also believes there is a low probability of a costly strike at Delphi, GM's former parts division, even though union members rejected Delphi's latest wage offer earlier this week. Delphi filed for bankruptcy protection last month.

"Although we expect high gas prices to hinder large vehicle sales, we project rebounding sales volume of these vehicles and a return to profitability in 2006," S&P said.

But GM's mounting problems are causing speculation about the future of Wagoner and other top executives. GM's U.S. market share is falling, and it lost nearly $4 billion in the first nine months of this year, crippled by high health care and labor costs. It is under investigation by the Securities and Exchange Commission for accounting errors, and it also could be liable for billions in pension costs for Delphi retirees.

"If the company continues to go south the way GM is doing, it does raise questions about the confidence the board has in these people," said Gerald Meyers, the former chairman of American Motors Corp. who now teaches at the University of Michigan. "I know they are dealing as best they can, but it's just awful."