Why is this man smiling? GM CEO Ed Whitacre stands to make millions on a new stock award.

A dozen top General Motors executives will share millions in a potential stock bonanza added to their base pay, the automaker revealed Monday in Security and Exchange Commission filings.

The stock could help sweeten things for senior GM managers, many of whom have seen their pay restricted by the Treasury Department’s special compensation master as part of the terms of the $50 billion bailout that pulled the automaker out of bankruptcy last year.

While the precise value of the new shares will ultimately depend upon the success of GM’s planned Initial Public Offering, or IPO, some observers estimate the latest round of incentives will be worth $13 million or more.

The awards were disclosed as part of a required filing with the U.S. Securities and Exchange Commission.  Data on corporate earnings and compensation for senior executives is part of the public record.

Stock awarded last year became exercisable as of March 2010, and the company’s filing said it will be paid in cash “in an amount equal to the fair market value,” though exactly what that value will be cannot be determined until the IPO.

GM placed a value of preliminary value of $38.87 on the shares issued in 2009, and $53.98 on those being awarded this year, but those are considered only temporary valuations that will almost certainly change over time.

The White House has been pressuring GM to take itself public again as soon as possible, hoping to recover as much as possible of its investment.  But CEO Ed Whitacre has cautioned that he will not authorize an IPO until he believes it can generate maximum value.  Analysts like Joe Phillippi, of AutoTrends Consulting, do not expect that to be possible until at least 2011.

Executives receiving additional stock this year won’t be able to cash in until next year, and restricted stock options take three years to vest, according to the automaker.

The biggest payout under the salaried stock plan goes to Ed Whitacre, Jr., who now serves in the dual role of GM Chairman and Chief Executive Officer.  He receives 24,547 shares.  Others receiving stock include:

• Vice Chairman Tom Stephens, 50,521 shares;
• Chief Financial Officer and Vice Chairman Chris Liddell, who joined GM from Microsoft this year, gets 15,979 shares;
• Vice Chairman and Wall Street veteran Chris Girsky receives 18,063.  A key role for Girsky will be putting together the planned GM IPO;
• Mark Reuss, the president of GM’s North American operations, will get 25,104 shares.

The stock deal is ostensibly meant to help offset restrictions in salaries ordered by Kenneth Feinberg, Treasury’s special master on pay.  Responding to public outcry over the lavish bonuses awarded to senior executives of company’s receiving federal bailouts – especially those in the banking and finance industry – Feinberg has sharply curbed this year’s compensation, in many cases to no more than $500,000.

GM sought to get the government overseer to push 16 of its top 25 executives above that ceiling but he approved only eight.