The 547-page filing didn't set a share price. Thus, it didn't forecast how much taxpayers will get back of their $50 billion investment as the government begins to sell down the 60.8% U.S. stake in GM -- 304 million shares -- after the IPO.

GM said the market will set the price of shares.

Francis Gaskins, veteran IPO analyst, predicts, "Taxpayers will take a 50% loss." That's because Gaskins and many other analysts assume investors won't value GM higher than the $42 billion market capitalization of healthier Ford Motor. Ford and GM had about the same first-half revenue, but Ford profit was twice GM's.

Valuing GM even with Ford would make GM's 500 million shares worth about $84 each. But Treasury would need to sell its shares for an average of roughly $167 for taxpayers to be fully repaid.

Investors also will see that among the cautions in the obligatory "risk factors" section of the so-called S-1 GM made the startling acknowledgment that it still can't keep track of its money. Even after accounting fixes in the past year, GM said, "our internal control over financial reporting" is "not effective" and that could "affect our ability to report accurately our financial condition ..."

It also warned that its new CEO, Daniel Akerson, 61, appointed unexpectedly from the GM board just last Thursday, is untested in the auto business.

GM also said it has lost business because of "a negative public perception of our products," and it can't guarantee it will be able to change that.

The filing also did not specify how many shares would be offered and by which equity holders. Canadian governments, which aided the bailout, and a United Auto Workers retiree trust also took stakes as part of GM's 2009 bankruptcy reorganization.

In a statement, the U.S. Treasury said it will decide later "whether and at what level to participate in the offering."

The IPO also will include newly issued preferred shares separate from the stakeholders' common shares. Money from their sale will go to GM. Preferreds have first claim on company assets and dividends and can be converted into common shares.

Including preferred shares in an IPO is "definitely unusual," says Ryan Caione, IPO expert at Hoover's business information company.

Gaskins says they could undercut the price of less-appealing common shares, which GM says won't pay dividends.

The SEC normally acts on an IPO filing in about two months, Caione says. GM said its stock would be listed on the New York and Toronto exchanges.