Stock index futures fell on Thursday, following global stocks lower, as persistent fears over Greece's public finances unsettled investors worried about sovereign debt defaults in Europe.

Markets pounded Greek bonds and banking stocks, driving the country's borrowing costs to new highs and pushing it closer to tapping a last-resort safety net.

U.S. financial shares weakened in premarket trade, with Citigroup Inc down 1 percent to $4.32 and Bank of America Corp off 0.5 percent to $18.53. The Select Sector SPDR Financial ETF fell 0.3 percent.

Greece is the word that just seems never to go away, said Kim Caughey, senior equity research analyst at Fort Pitt Capital Group in Pittsburgh. What is the EU going to do, and structurally how are they going to address this? I think that's the big question because we have Spain, Portugal looming out there as well.

S&P 500 futures fell 3.8 points and were below 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 dropped 42 points, and Nasdaq 100 futures lost 4 points.

U.S. equities pulled backed Wednesday after hitting levels not seen in a year and half. The Dow industrials fell back from the psychologically important 11,000 level, with some analysts saying investors are taking profit with no catalyst to drive the market higher.

Data on weekly initial claims for jobless benefits is due before the bell, an important indicator on the state of the economy as optimism grows about the strength of the labor market. Economists in a Reuters poll expect that new claims fell by 4,000 last week.

A nascent pickup in consumer spending has expanded beyond discounters to other retailers, according to early reports on March sales. Limited Brands Inc reported same-store sales jumped 15 percent, sending the stock up 1.2 percent to $26 in premarket trade.

But Abercrombie & Fitch Co said March sales rose 5 percent, but were below estimates. The stock fell 4.5 percent to $45.41 premarket.

Shares of UAL Corp , parent of United Airlines, jumped 7.2 percent to $20.33 in premarket trade after the New York Times reported the company was in merger talks with US Airways Group Inc , citing sources.

The pan-European FTSEurofirst 300 <.FTEU3> index of top shares fell 1.2 percent, while the euro inched closer to a 2010 low against the dollar on jitters over Greece.

(Reporting by Edward Krudy; editing by Jeffrey Benkoe)