DETROIT — Not much has gone right this year for General Motors Corp., which has seen quarter after quarter of huge losses, production cuts, falling U.S. market share and high gas prices.

So it was with much relief yesterday that GM Chairman and CEO Rick Wagoner announced a tentative agreement with the United Auto Workers that could save the company $3 billion a year before taxes in healthcare costs. GM has lost $3 billion in the first nine months of this year.

"It was critical for Rick, critical for the company and really for the whole industry," said David Cole, chairman of the Center for Automotive Research. "GM's board didn't have Rick on a short leash and they weren't threatening his removal, but they clearly expected to see something of substance and they got it."

Wall Street analysts reacted positively to the news, although some said GM's challenges are so numerous and varied that the healthcare agreement may not be enough. Among those challenges are competition from leaner Asian automakers, healthcare inflation, huge pension obligations and GM's heavy reliance on sport utility vehicles, which have been faltering as gas prices rise.

"Severe operating challenges still confront GM, including mix, pricing and market share pressures plus a tough macro outlook as consumers face rising interest rates and energy costs," Goldman Sachs analyst Robert Barry said in a note to investors.

GM, the world's largest automaker, said yesterday that it lost $1.6 billion in the third quarter, or $2.89 per share, compared with a profit of $315 million, or 56 cents a share, a year ago. The loss included charges of $861 million for restructuring and lower asset values in North America and Europe.

Prompted by its deteriorating credit rating, GM also said it may sell a controlling interest in its profitable finance arm, General Motors Acceptance Corp., despite the boost GMAC gives the struggling automaker's bottom line.

For the day, at least, investors saw the bright side of GM's outlook. Its shares rose $2.11, or 7.5 percent, to close at $30.09 on the New York Stock Exchange. They gained 12 percent earlier in the day and have traded in a 52-week range of $24.67 to $42.22.

John Devine, GM's vice chairman and chief financial officer, said the tentative agreement on healthcare would reduce GM's retiree healthcare liabilities by about 25 percent, or $15 billion, over seven years. Cash savings are estimated at around $1 billion annually.

GM pays for healthcare for 750,000 U.S. hourly employees, retirees and their dependents. The company expects to spend $5.6 billion on healthcare this year. GM's UAW members now pay 7 percent of their healthcare costs, while the company's salaried employees pay 27 percent, according to GM. It's not yet clear how that will change under the agreement.

Himanshu Patel, an auto analyst with JPMorgan Chase & Co., said the agreement will make a substantial dent in GM's $80 billion healthcare liability.

Wagoner said the agreement marks the largest reduction GM has ever announced in a single day. GM had asked the UAW to help it lower its healthcare costs before its contract with the union expires in 2007, and both parties have been negotiating since the spring.