DETROIT, Nov. 7, 2007 (AP) -- General Motors Corp. posted a $39 billion net loss in the third quarter, as an accounting shift involving deferred taxes brought an abrupt end to string of three profitable quarters for the nation's largest automaker.

The whopping loss announced Wednesday was attributed to a $38.6 billion noncash charge largely related to establishing a valuation allowance against deferred tax assets in the U.S., Canada and Germany, as well as mortgage losses at GM's former financial arm, GMAC Financial Services.

A valuation allowance is taken when the future benefit of the deferred tax assets is less likely to be realized.

The net loss amounted to $68.85 per share, compared with a net loss of $147 million, or 26 cents per share, in the third quarter of last year.