How bad can it get? Check out what happened to GM's stock today:

DETROIT - General Motors shares fell to their lowest level since 1950 on Thursday as concerns mounted that an industry decline that started in the United States was spreading and a leading forecaster warned global auto demand could "collapse" in 2009, according to Reuters.

GM shares fell as much as 22 percent to $5.42 -- driving its market capitalization to its lowest level since 1929, according to California-based Global Financial Data.

Shares of Ford Motor Co, which hit a quarter century low on Wednesday, shed as much as 13.5 percent and major auto parts makers declined as well.

GM's market cap stands at about $3.3 billion, compared with a market cap of about $4 billion in March 1929 before the stock market crash that preceded the Great Depression.