Fitch Ratings is lowering its credit rating for General Motors to junk status.
GM shares and bonds fell on the news, which could lead to it paying more to borrow in the future, and complicate its attempt to cut costs.
The move reflects the impact of sales declines and price competition within the auto industry. Standard & Poor's downgraded GM status earlier this month.
Fitch's decision today also effectively robs the automaker of its investment-grade status in the widely watched Lehman Brothers Credit Index.
Lehman Brothers plans in July to eject those companies whose average rating at Fitch, S&P and Moody's Investors Service is junk.
The exclusion would bar many institutional investors from holding the debt.