The economy contracted at a far faster rate than initially estimated in the final months of 2008, the government reported Friday, suggesting a deeper recession that will further challenge the health of the financial system.

Financial stocks led the market down on economic worries in general and concerns about nationalization, after the government announced that it was vastly increasing its stake in Citigroup.

In the fourth quarter, the gross domestic product fell at an annualized rate of 6.2 percent, the steepest decline since the 1982 recession and sharper than the 3.8 percent reported earlier. Every major component of the economy shrank, except government spending. Economists said all signs point to a similar drop in output in the current quarter.

“What a ghastly report,” said John Ryding, chief economist at RDQ Economics. “This will almost certainly be the longest postwar recession, and now potentially the deepest one as well.”