Troubled U.S. auto giant General Motors is running into more trouble with its stock plunging more than 20 percent Tuesday to hit a 76-year low.

The drop came as documents filed with U.S. regulators showed six current and former GM executives sold all of their shares in the company.  

GM is surviving on $15 billion in emergency loans from the government and has until June 1 to restructure or declare bankruptcy.  On Monday, GM Chief Executive Fritz Henderson warned bankruptcy is "more probable."

Meanwhile, the number two U.S. auto company is trying to raise billions of dollars .

Ford Motor Company Tuesday began selling 300 million shares of common stock to investors.

Ford lost almost $15 billion last year but, so far, it is the only U.S. car company not to ask for government help.

Japanese auto makers are also struggling.

The world's top carmaker, Toyota, said Tuesday it is suspending some operations at its main engine factory indefinitely to adjust for slowing demand.  

Toyota last week posted the worst financial results in its 72-year history, losing $7.7 billion in the January-March quarter.   Officials at the Japanese auto giant are forecasting more losses this year.

Mazda, Japan's second largest car exporter, said Tuesday it lost more than $730 million in the past year, although it forecast that loss will narrow in 2010.

Japan's number three auto company, Nissan, announced Tuesday it lost $2.4 billion in the past year.

Nissan Chief Executive Carlos Ghosn told Bloomberg he hopes the auto industry will begin to recover at some point in 2010.  He also said the only region where Nissan anticipates increasing its market share is China.

There may be trouble for automakers in another emerging economy.

The Association of European Businesses said Tuesday sales of new car and trucks in Russia fell 53 percent in April.


Some information for this report was provided by AP and Reuters.