NEW YORK (CNNMoney.com) -- General Motors posted third-quarter operating profit Wednesday that nearly doubled Wall Street's earnings expectations as its turnaround efforts continued to show results.

The nation's No. 1 automaker earned $529 million, or 93 cents a share excluding special items, compared with a loss of $1.1 billion, or $1.97 a share on that basis a year earlier.

Analysts surveyed by Briefing.com had forecast earnings of only 49 cents a share in the period.

While special charges still left GM with a narrow net loss in the period, the result was the second straight quarter that the company posted an operating profit after five straight quarters of large losses.

Revenue from auto sales also topped forecasts, but only slightly, rising to $39.5 billion from $38.4 billion a year earlier. Analysts had forecast sales of $38.8 billion.

While not all of its problems are behind it, GM's improved results in what is a traditionally difficult period for auto profits show it is achieving some of the cost-cutting goals it set out a year ago.

GM still reported a narrow loss on its core automotive operations, but shaved $1.3 billion of losses from its North American operations, as it instituted labor and health care cost savings negotiated over the past 12 months with the United Auto Workers union. The company said it is on track to reach $6 billion in annual cost savings from those moves this year.

The company also cut its announced exposure to costs associated with the bankruptcy of auto parts maker Delphi (Charts). GM (Charts) said it now could be on the hook for between between $6 and $7.5 billion in pre-tax obligations to its former parts unit, as compared to a previously disclosed range of $5.5 to $12 billion.

Still shares of GM (down $1.39 to $34.80, Charts), a Dow Jones industrial average component, were down in morning trading on the report. Shares closed up $1, or nearly 3 percent, in trading Tuesday on anticipation of better-than-forecast results.

Kevin Tynan, auto analyst for Argus Research, said he thinks the sell-off Wednesday is partly an example of selling-on-the-news, and also on concerns that the company continues to lose money on its auto operations despite the improvements that have been made.

"There's concern about sustainability of recovery of auto operations, which are still losing money and burning through a lot of cash," said Tynan. "While it's easy to say we're moving in the right direction, there's still a lot of problems out there."

Tynan, who does not own any GM shares, has a $40, 12-month price target on the stock and a short-term "buy" recommendation. But he also has a "sell" recommendation for investors who have a longer-term investment outlook.

While the number of vehicles sold in North America fell 8 percent, revenue from that core market edged up just less than 1 percent, with GM posting stronger sales of its newly designed SUVs compared to a year earlier despite higher gas prices at the beginning of the most recent quarter.

The auto revenue helped lift overall revenue to $48.8 billion from $47.2 billion a year earlier. The charges associated with staff buyouts and early retirements, other restructuring moves and the sale of its GMAC finance unit left the company with a net loss in the period of $115 million, or 20 cents a share. But that's an improvement from the loss of $1.7 billion, or $2.94 a share, in the year-earlier period.

GM still did not give guidance as to when it will return to profitability in its core auto operations, despite the good news on costs and sales. The company previously had said it needed to wrap up the sale of GMAC and a labor deal with Delphi before it would give such guidance.

But Wednesday, Chief Financial Officer Fritz Henderson would not commit to when or if it might now give a profit outlook once again.

"I can't promise anything," he said. "It's a debate we have to go through ourselves internally."

GM's report comes two days after competitor Ford Motor Co. (Charts) reported a bigger than expected loss. Honda Motor (Charts) also reported disappointing results Wednesday although it raised its full year guidance on strong U.S. sales.

DaimlerChrysler (Charts) also reported results Wednesday morning, as the German automaker overcame a $1.5 billion loss at its Chrysler Group unit to report a better-than-expected profit. It also reaffirmed its full-year earnings guidance.

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