* S&P 500 has gained 1.9 percent over past two sessions

* Fourth-quarter GDP may be revised to show growth

* J.C. Penney, Groupon both sink on weak revenue

* Futures up: Dow 10 pts, S&P 1.2 pts, Nasdaq 4.75 pts

By Ryan Vlastelica

NEW YORK, Feb 28 (Reuters) - U.S. stock index futures edged higher on Thursday as investors were reluctant to make big bets following a sharp two-day rally and ahead of a rash of data.

Analysts said a pullback may be in store a day after major equity indexes posted their biggest daily advance since early January. Over the past two sessions, the S&P 500 has gained 1.9 percent, rising back above the closely watched level of 1,500.

Wall Street has largely resisted expectations it would undergo a correction, with the Dow Jones industrial average within striking distance of an all-time high. Recent gains were fueled by strong data and comments from Federal Reserve Chairman Ben Bernanke that showed continued support for the Fed's economic stimulus policy.

Revised gross domestic product data is expected to show that the U.S. economy grew 0.5 percent in the fourth quarter, rather than contracted 0.1 percent, as initially estimated. The data is due at 8:30 a.m. (1330 GMT), as are weekly jobless claims, which are seen dipping by 2,000 to 360,000 in the latest week.

"A rise in GDP is clearly part of the market's expectation at this point, and if it disappoints, there's a real risk to the downside," said Oliver Purshe, president of Gary Goldberg Financial Services in Suffern, New York.

Purshe noted that on Feb. 18, about 80 percent of S&P 500 components were above their 50-day moving averages, a rate that has since dwindled to 60 percent.

"Market breadth has narrowed, and which suggests that a correction of as much as 5 to 6 percent is very likely."

While markets suffered steep losses earlier this week on concerns over European debt, they have since recovered and are little changed on the week.

Investors will also be keeping an eye on the debate in Washington over sequestration - U.S. government budget cuts that will take effect starting on Friday if lawmakers fail to reach an agreement on spending and taxes. President Barack Obama and Republican congressional leaders arranged to hold last-ditch talks to prevent the cuts, but expectations were low that any deal would be produced.

"Investors have come to the realization that sequestration isn't the end of the world and that it will eventually be fixed," Pursche said. "But going into March the risk is that the economy slows down and disappoints investors."

S&P 500 futures rose 1.2 points and were above fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures added 10 points and Nasdaq 100 futures rose 4.75 points.

For the month of February, the S&P 500 is up 1.2 percent, the Dow is up 1.6 percent and the Nasdaq is up 0.6 percent.

J.C. Penney Co Inc shares slumped 15 percent to $18.01 in premarket trading a day after it reported a steep drop in sales, prompting the department store to overhaul its pricing strategy. Groupon Inc also slumped on weak revenue, with the stock off 26 percent at $4.41 before the bell.

Sears Holding Corp rose 3.2 percent to $49 in premarket trading after it reported earnings and sales that beat expectations.

Tim Cook, chief executive of Apple Inc, acknowledged widespread disappointment Wednesday in the performance of the tech titan's stock, which is down 16.5 percent so far this year, but urged investors to take a long-term view on the company.

With 93 percent of the S&P 500 companies having reported results so far, 69.5 percent have beaten profit expectations, compared with a 62 percent average since 1994 and 65 percent over the past four quarters, according to Thomson Reuters data.

Fourth-quarter earnings for S&P 500 companies are estimated to have risen 6.2 percent, according to the data, above a 1.9 percent forecast at the start of the earnings season.

U.S. stocks rallied on Wednesday, lifted by positive comments from U.S. Federal Reserve Chairman Ben Bernanke. Adding to the positive tone in markets were data showing robust pending home sales and a proxy for business spending plans that was stronger than expected.