NEW YORK (CNN/Money) - General Motors Corp.'s first quarter loss -- the biggest in 13 years -- was about as bad as expected, but the company's lack of guidance about the problems facing the world's No. 1 automaker sent its stock skidding Tuesday.

GM said it lost $839 million, or $1.48 a share, excluding special items, in the quarter, versus profits of $1.3 billion, or $2.25 a share, a year earlier. GM had warned investors in March it expected to lose about $1.50 a share in the quarter on that basis. At the time, analysts had been looking for only a loss of 3 cents a share.

On a net basis, GM lost $1.1 billion, or $1.95 a share, in the quarter, including restructuring and severance charges for job cuts in Europe and the United States. Most of the staff cuts were through early retirement programs.

As if that weren't bad enough, GM said that due to uncertainty about its attempts to cut health care costs, it would not give any full-year earnings guidance. Last month, when it warned of the first-quarter loss, it said it expected full-year earnings of $1 to $2 a share.

GM (down $0.31 to $25.88, Research), one of 30 stocks in the Dow industrials, tumbled almost 6 percent to an intra-day low before regaining most of that ground in mid-afternoon trading as the broader market rallied.

Analysts had a full-year earnings forecast of 67 cents before Tuesday's report, down from their earlier target of $3.33 a share at the time of the company's March warning.

Chief Financial Officer John Devine told analysts the amount being spent on health care is known but the company is looking at ways to cut that. "The issue is what we do about it. I don't want to get too far discussing it today," he said. "The specifics get into a number of issues, some of which are labor related. We do not negotiate in the media."

But Devine was challenged by analysts about why GM was no longer staying with its earlier full-year earnings forecasts.

"I have to assume that prior guidance did not assume any ground breaking concessions from labor," said Darren Kimball, Lehman Brothers' auto analyst.

But Devine said he could not give anything that resembled earnings guidance.

Questions from analysts expressed skepticism bordering on hostility.

"It's obvious that the math doesn't seem to work," said Rod Tadross of Bank of America Securities. "You can't do on the labor side anything close to what you need to break even."

Devine responded to Tadross: "We probably have a different view than you."

Tadross pressed Devine as to when the company would be willing to give details of its turnaround plan and full-year financial target. Devine declined to say.

"If you're looking for me to lay out a program to get us into profitability, I'm not set to do that today," he said. "As soon as we have something to tell you, we will."

Officials with the United Auto Workers union told reporters last week that the union was not willing to reopen the current labor contract that runs through 2007, although it said it would work with the company on cost-saving efforts that can be achieved under the contract.

Devine did dispute recent speculation that GM was looking to get rid of one or two of its brands. Last month, Vice Chairman Robert Lutz referred to Buick and Pontiac as "damaged brands" and said that while they could be turned around, they might be closed at some point, absent improvement.

"We have product and distribution plans to fit each of those brands," Devine said, without mentioning any names. "I know there's a lot of speculation about what we're doing and that's fine. But I want to be clear we do not have plans to drop any brands."

The net loss was the worst since GM lost a whopping $21 billion, due mostly to accounting changes, in the first quarter of 1992.

Sales fell 4.3 percent to $45.8 billion. Revenue outside its finance units fell 7 percent to $37.3 billion, missing First Call's forecast of $37.9 billion.

Devine said the company saw fewer sales of higher-priced, more profitable sport/utility vehicles and pickups, and more sales of small SUVs and cars, in the quarter. GM's sales mix has been "relatively strong in recent years," Devine said. "And after reasonably stable (U.S. market) share the last four to five years, we're down this year, and it hurts."

Devine said the key to any turnaround plan is to offer new products that get good reaction from buyers. The company is planning many new vehicle introductions in the coming year, especially SUVs.

"We have full confidence in our product team," he said. "You're going to see the results. We think we're coming on strong."

The company lost $1.3 billion from its core North American auto unit, compared to profit of $401 million a year earlier. European auto operations lost $103 million, a slight improvement.

Even in Asia, where GM's auto operations earned $60 million, that was down from $275 million a year earlier. Only its Latin America, Africa and Middle East units saw significant improvement, earning $46 million, compared to $1 million a year earlier.

The company's finance operations saw a slight decline in earnings to $729 million from $764 million a year earlier.