U.S. Economy: Grim mood hits Wall Street
Financial markets also did not appear comforted by an afternoon statement by President Barack Obama, who said Washington needs more "common sense and compromise" to tame its debt.
"Markets will rise and fall," he said. "But this is the United States of America. No matter what some agency may say, we've always been and always will be a triple-A country."
S&P, in its downgrade, criticized dysfunction in the American political system. The downgrade wasn't a total surprise but came when investors were already feeling nervous about the U.S. economy and European debt, among other problems.
Last week, the Dow Jones industrial average fell almost 700 points. That was its biggest weekly point loss since 2008, during the financial crisis. Counting Monday, the Dow has dropped in 10 of the last 12 trading days. It is down more than 1,900 points, or 15 percent, since July 21.
The Russell 2000 index of small stocks has now lost nearly 25 percent from its most recent high on April 29. A decline of 10 percent or more is considered to be a correction. And a drop of 20 percent or more is said to be the start of a bear market.
The Nasdaq and S&P 500 are both down about 18 percent since the end of April. The Dow is down 16 percent.
The last bear market for the S&P 500 ran from October 2007 until March 2009. The index lost 57 percent of its value.
Despite the slide the last two and a half weeks, the S&P 500 index, at 1,119, is 7 percent higher than its close of 1,047 late last August, just before the Federal Reserve announced a program to support the economy. And the Dow's percentage drop of 5.5 didn't make the list of its 20 worst days.
S&P on Monday downgraded mortgage lenders Fannie Mae, Freddie Mac and other agencies linked to long-term U.S. debt. Fannie andFreddie own or guarantee about half of all U.S. mortgages. Their downgrade could eventually mean higher mortgage rates.
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