General Motors Corp., the iconic automotive giant that once raised antitrust concerns with its market dominance, filed for bankruptcy protection yesterday, a widely anticipated step that many observers see as the company's best chance for survival.

The plan calls for the federal government to take a 60 percent ownership stake in the new GM. The Canadian government would take 12.5 percent, with the United Auto Workers getting 17.5 percent and unsecured bondholders receiving 10 percent.

Existing GM shareholders are expected to be wiped out.

General Motors will use $30 billion of additional financial assistance from the Treasury Department and $9.5 billion from Canada. That's on top of about $20 billion in U.S. taxpayer money that the automaker already has received in the form of low-interest loans.

President Barack Obama yesterday said the federal government would be a "reluctant shareholder" in GM, and he pledged the government would not be in the business of telling the company how to manage its day-to-day affairs. "What I am not doing, what I am not interested in doing, is running GM," he said.

The toll that even a successful proceeding will take in real, human terms was made clear.

In a news conference, the company said it planned to cut 21,000 employees -- about 34 percent of its work force -- and reduce the number of dealers by 2,600. GM said it was finalizing a deal to sell the Hummer line, and plans for Saturn were expected to be announced within weeks.

As part of its reorganization, GM also said it would permanently close nine more plants and idle three others. Pontiac, Mich., and Wilmington, Del., assembly plants will close this year, while plants in Spring Hill, Tenn., and Orion, Mich., will shut down production but remain on standby. One idled plant will be retooled to build a small car that GM had originally planned to build in China.

Seven powertrain and parts stamping plants will be closed starting in June 2010, while an additional stamping plant will be idled but remain in a standby capacity.

Todd Horton, editor of the newsletter at the Spring Hill factory's United Auto Workers local, said the 2,500 employees got the news of the shutdown yesterday morning. He said the Chevrolet Traverse crossover vehicle built there would be made in Lansing, Mich., instead.

The company earlier sent letters to more than 1,000 dealerships, telling them that it would not renew their contracts after 2010.

Yet, everyone, from GM Chief Executive Fritz Henderson on down, said there was little left to do other than extract more sacrifices, because the alternative would be too grim to even consider. "There is no other sale, or other potential purchasers, present or on the horizon," he said in an affidavit filed yesterday in bankruptcy court.

"The only other alternative is the liquidation of the debtors' assets that would substantially diminish the value of GM's business and assets, [and] throw hundreds of thousands of persons out of work and cause the termination of health benefits and jeopardize retirement benefits for current and former employees and their families."

The impact on consumers and workers will be different, according to Jack Nerad, editorial director of the Kelley Blue Book. He said that to the typical consumer, the General Motors bankruptcy will be largely invisible. "In most instances, their local GM-affiliated dealerships will continue to operate, selling new and used vehicles and dispensing service and parts." The government has said warranties will stay in effect.

"For the workers idled by the closing of 14 plants, the effect will be far different -- a sudden change in the way of life of many communities that have relied on the strength of the American auto industry," Mr. Nerad said.

GM's bankruptcy filing is the fourth-largest in U.S. history and the largest for an industrial company. The company said it has $172.81 billion in debt and $82.29 billion in assets.

In an early indication of how complicated the reorganization process will be, more than 100 legal filings had already been submitted by around 2 p.m. yesterday to the Southern District of New York Bankruptcy Court. Since this is a pre-packaged bankruptcy, players have had plenty of time to prepare necessary documents ahead of time.

Meanwhile, despite the failures that bankruptcy represents, there seemed at GM to be a feeling of optimism. One public relations person who answered the phone late last week reported noting a sense of relief and hope for the future -- "just rolling up our sleeves and getting on with it -- and doing it right."

Optimism was the note sounded at a New York news conference by the company's Mr. Henderson. "This new GM will be built from the strongest parts of our business, including our best brands and products," he promised.

U.S. Sen. Carl Levin, D-Mich., expressed the sentiment that seemed to be in many people's minds yesterday. "I'm confident this is far better than the alternative. It's a new beginning, it's a rebirth, it's a new General Motors," he said.

Despite the reassurances by Mr. Obama and others, there still is widespread opinion that the idea of the federal government's getting involved in running private companies such as GM is a dangerous one.

"Our biggest concern with the restructuring plan ... is the potential for governments and unions to influence production, work force and management decisions in ways that could jeopardize the automakers' chances for survival, put politics and special interests above sound business strategy, and disrupt our nation's trading relationships across the world," said Thomas J. Donohue, president and CEO of the U.S. Chamber of Commerce.

He vowed that the chamber would carefully monitor the actions of the new GM and Chrysler boards and fight any counterproductive influence by government, unions or politicians.

Some had words of advice for the bankruptcy court.

The court should take care not to trample on recognized rights under state franchise laws, said John McEleney, chairman of the National Automobile Dealers Association. "GM dealers are independent business owners -- men and women who have invested millions in their facilities and are the cornerstones of the economies in their local communities."