It took a while, but investors eventually decided they liked what they heard from Ben Bernanke, and stock indexes rose enough on Friday to put them into positive territory for August.

Stocks gyrated after the Federal Reserve chairman spoke on Friday morning. They first give up their gains for the morning, then set new highs for the day, then settled in-between. The Dow Jones industrial average closed 90 points higher, up a half-percent at 13,090. The Standard & Poor's 500 index rose seven points to close at 1,406. The Nasdaq rose 18 points to almost 3,067.

Advancing stocks outnumbered decliners more than 2-to-1.

The Dow finished the month of August up by 0.8 percent. The S&P 500 rose more than 2 percent for the month, and the Nasdaq rose more than 4 percent.

A half-hour after trading began, Bernanke declared that the Fed is ready to take more action to help an economy that's "far from satisfactory." Stocks gave up their strong gains from the morning, and the Standard & Poor's 500 index and Nasdaq turned slightly negative.

Investors have been watching to see whether the Fed will buy more bonds to further lower long-term interest rates. Stocks fell after it became clear that, indeed, no such announcement was coming Friday, and Bernanke stopped short of committing the Fed to any specific move. Still, he said the Fed "should not rule out" new policies to improve the job market.

Stocks rebounded once investors parsed his

In terms of volatility, "it's been the most action we've seen in couple of weeks," said Ryan Larson, a senior equity trader at RBC Global Asset Management. He noted that pre-Labor day volume was light. Many investors and traders are on vacation, which can contribute to bigger price swings.

In afternoon trading, the Standard & Poor's 500 index was up 6 points at 1,405. The Nasdaq was up 14 points at 3,063. The Dow was at 13,078.

Investors who are hoping for help from the Federal Reserve may only have one more chance before the election, said Frank Fantozzi, CEO of Planned Financial Services in Cleveland. The Fed's policy-making arm meets on Sept. 13. If it doesn't announce some form of stimulus then, it probably won't until after the election, he said.

"He's waiting until the last possible minute," Fantozzi said of Bernanke. "I think in the next two weeks they're going to really digest the economic data and say, 'Ok, do we get involved or not?'"

Bernanke's comments on Friday got more uniform reception in energy markets, which tend to rise on bullish signs for the economy. Oil prices jumped $1.81 to $96.42 per barrel on the New York Mercantile Exchange. Natural gas and wholesale gasoline prices both rose more than 2 percent.

Also Friday, the Commerce Department said factory orders rose 2.8 percent in July on surging demand for autos and commercial planes. However, orders for core capital goods -- a key measure of investment spending -- dropped 4 percent. That was that figure's fourth decline in five months.

Investors seemed more focused on Bernanke's comments and the overall higher factory orders, though.

Stocks rose in nine out of 10 industry groups in the S&P 500. Utility stocks declined slightly. Energy stocks had the biggest gain, up 0.8 percent.

Other shares with big moves on Friday included:

-- Facebook set new lows, falling $1, or 5.31 percent, to $18.09 per share. Its previous intraday low was $18.75. The stock is down 52 percent from its $38 initial public offering price.

-- US Airways Group Inc., up 2.6 percent after disclosing that it signed a confidentiality agreement that signals the beginning of talks with American Airlines for a possible merger.

-- Zumiez fell almost 10 percent after the specialty sports and clothing retailer said third-quarter earnings would be lower than analysts had expected.

-- Science Applications International Corp. rose 2.7 percent after saying it will split at the end of next year into two businesses, with one focusing on national security, engineering and health customers, and another focused on government customers.

Stocks in Europe were mixed. The German DAX and the CAC 40 in France both rose about 1 percent. The FTSE 100 in Britain fell 0.1 percent.

The dollar fell, with the euro rising to $1.258, and the Japanese Yen rising against the dollar to 78.33.