DETROIT (Reuters) -- General Motors Corp. stock plunged more than 22% to a 76-year low Tuesday, a day after a group of GM executives disclosed they had sold shares in the struggling automaker.

Six GM executives, led by former GM Vice Chairman and product chief Bob Lutz, disclosed Monday that they sold almost $315,000 in stock and liquidated their remaining direct holdings in the automaker.

The stock sale underscores the extreme pressure on GM with less than three weeks remaining for the embattled automaker to win deals to slash debt and operating costs with its major union and bondholders to avoid bankruptcy.

GM (GM, Fortune 500) is headed for either a bankruptcy filing or an out-of-court restructuring that would wipe out current stockholders by flooding the market with new shares to pay off creditors.

The automaker's stock could be worthless in a bankruptcy or worth less than 2 cents apiece if it proceeds with plans to issue shares to creditors led by the U.S. Treasury Department, the company has said.

"It's a lose-lose situation as far as we see it, and the shares kind of seem to have been doing a levitating magic trick and just staying up there in the $1.50 to $2.00 range," Standard & Poor's equity analyst Efraim Levy said.

"Given that there is a two-week deadline coming there should be additional downside pressure," Levy said.

The automaker has historically been one of the powerhouses in the best-known measurement of U.S. stocks, the Dow Jones Industrial Average. It has been on the index for 83 consecutive years and despite the dramatic fall in the price of its shares, Dow has still kept the stock as part of the index.

GM's market capitalization as of Tuesday was about $690 million, making it one of the smaller Dow members.

The company has lost $88 billion since its turnaround efforts began in 2005 under former Chief Executive Rick Wagoner.

The automaker's shares were down 21% or 30 cents, at $1.14 on the New York Stock Exchange. The stock had fallen to as low as $1.09 earlier in the day, the lowest since 1933.

GM was first listed on the Dow in 1915. Journal editors removed it - as they did more frequently back then - adding it again in 1925, and it has remained ever since. Only General Electric Co. (GE, Fortune 500), which joined in 1907, has been there longer.