U.S. stock-markets started slightly up after reports showed that  the U.S. economy grew more than expected and worry about the European Central Bank's refinancing operation and awaited economic data and testimony from Federal Reserve Chairman Ben Bernanke.

On the last trading day of the month, the markets opened with the Dow Jones Industrial Average up 6 points to 13,003. S&P 500 gained 0.9 point to 1,372.30. Nasdaq 100  slightly up 2 points to 2,634.

U.S. stock-index futures gained after the federal agency reports said the American economy expanded more than previously estimated in the fourth quarter as companies rebuilt inventories.

Gross domestic product climbed at a revised 3 percent annual rate, the most since the second quarter of 2010.

The S&P 500 is heading for a 4.6 percent monthly gain. It has rallied 9.1 percent this year on optimism the U.S. economy is recovering and the euro area's debt crisis will be contained. The Dow yesterday closed above 13,000 for the first time since 2008.

Markets climbed earlier after the European Central Bank said today it will lend 800 financial institutions 529.5 billion euro ($712 billion) for 1,092 days. Economists predicted an allotment of 470 billion euro, according to the median of 28 estimates in a Bloomberg News survey. The first tender saw 523 banks borrow 489 billion euro in December.

Federal Reserve Chairman Ben S. Bernanke will deliver testimony on monetary policy and the outlook for the economy to the House Financial Services Committee in Washington today.

The Fed chairman said last month that the central bank is considering buying more bonds after policy makers agreed to keep the width=150benchmark interest rate at exceptionally low levels at least through late 2014. The Fed has completed two rounds of asset purchases, or quantitative easing, totaling $2.3 trillion so far.

This should close out a very chaotic month for investors, and the markets. Tomorrow's economic calendar is jammed packed with information due all around the world. The end of a week, the beginning of a month following a February 29, 2012, no one can predict what will happen tomorrow.