S&P

The U.S. stock market ended its worst week since the financial crisis with the Dow Jones Industrial Average falling 12.4%. Fed Chairman Jerome Powell promises to support the economy as necessary.

Defending itself from a U.S. lawsuit, S&P said the government was punishing it for exercising its free speech.

The rise is being tied to a drop in weekly jobless claims, as well as assurances from the Federal Reserve that it would continue to support the U.S. economy.

The credit rating agency had previously listed the United States' credit outlook as negative. They cited improved tax receipts and the attention being paid to the long-term budget as reasons for the upgrade.

Though stocks took a breather Monday from their recent rally, there are reasons to think they'll continue their upward move in coming months. Money seems to be moving out of bonds and into stocks, corporate earnings are better than expected and economies overseas are getting back on their feet.

The stock market hit some major milestones this week: The Standard & Poor's 500 index reached its highest level in more than three years and the Nasdaq rose to its highest level in 11 years. Still, the Federal Reserve has been warning not to get too excited about where the economy is headed next.

The Dow registered its highest reading in close to four years.