* S&P 500 has gained 1.9 percent over past two sessions
* Q4 GDP revised to show growth, but less than expected
* J.C. Penney, Groupon both sink on weak revenue
* Dow down 1 pt, S&P up 0.8 pt, Nasdaq up 4.25 pts
By Ryan Vlastelica
NEW YORK, Feb 28 (Reuters) - U.S. stock index futures pointed to a flat open on Thursday as investors found few reasons to keep pushing markets higher following a sharp two-day rally and a read on economic growth that was weaker than expected.
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.
The U.S. economy grew 0.1 percent in the fourth quarter, a weaker pace than expected, although a slightly better performance in exports and fewer imports led the government to scratch an earlier estimate of an economic contraction.
Separately, the number of Americans filing new claims for unemployment benefits fell more than expected last week, suggesting the labor market recovery was gaining some traction.
"The GDP revision is positive but nothing to write home about, especially since it missed estimates," said Adam Sarhan, chief executive of Sarhan Capital in New York.
While markets suffered steep losses earlier in the week on concerns over European debt, they have since recovered, with the gains fueled by strong data and comments from Federal Reserve Chairman Ben Bernanke that showed continued support for the Fed's economic stimulus policy.
"Bulls are still leading the market with the pullback bought up quickly, but we're in a wait-and-see period after the big move we've had," said Sarhan.
S&P 500 futures rose 0.8 point 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 dipped 1 point and Nasdaq 100 futures rose 4.25 points.
So far in February, the S&P 500 has gained 1.2 percent, the Dow is up 1.6 percent and the Nasdaq has added 0.6 percent.
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," said Oliver Pursche, president of Gary Goldberg Financial Services in Suffern, New York. "But going into March the risk is that the economy slows down and disappoints investors."
Pursche 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," he said.
J.C. Penney Co Inc shares slumped 17 percent to $17.61 in premarket trading after the department store reported a steep drop in sales on Wednesday. Groupon Inc also slumped on weak revenue, with the stock off 29 percent at $4.23 before the bell.
Sears Holding Corp rose 2.8 percent to $48.79 in premarket trading after its earnings and sales beat expectations.
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.