For Wall Street, Standard & Poor's downgrade of the U.S. is one more sign that dysfunctional government is contributing to the market's decline.

After the 2010 election, many on Wall Street welcomed divided government, on the theory that the less Washington does, the better markets do. Now, investors have changed their tune and once again are calling on Washington to fix things.

Markets have become addicted to government aid over the past decade, and a growing number on Wall Street are hoping again for a bailout from the Federal Reserve, Congress or both. Investors want decisive action at a time when Washington seems incapable of providing it.

That is one reason that some money managers have begun warning clients to expect more declines.

"We believe the bull market that began in 2009 is probably over," says Andrew Engel, senior research analyst at Leuthold Group in Minneapolis, which until recently was bullish but warned clients to pull back from stocks on the day before the Dow Jones Industrial Average fell more than 500 points Thursday.