Stock index futures rose on Thursday as investors looking for an earnings season rally maintained interest in the market after a sharp fall the previous session, but concerns over Europe's debt crisis capped gains.

Wall Street has been susceptible to wild swings on headlines coming out of Europe and on Thursday, investors took some heart in a report the euro zone's bailout facility will be able to buy bonds on the secondary market.

If we can get through this European thing I think the market wants to move higher based on the economic and earnings news but it just needs to get this fear out of the way, said Paul Mendelsohn, chief investment strategist at Windham Financial Services in Charlotte, Vermont.

Investors are closely watching the developing U.S. earnings season which so far has produced mixed results. Many are hoping a strong performance will power equities into the end of the year. Microsoft and AT&T are among companies reporting results on Thursday.

S&P 500 futures rose 3.2 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 55 points, and Nasdaq 100 futures climbed 0.25 points.

In Europe, shares trimmed losses on Thursday after a guideline document obtained by Reuters said the region's European Financial Stability Facility rescue fund would be able to buy bonds on the secondary market. However, the market was still nervous ahead of a European Union summit this weekend and the FTSEurofirst 300 index <.FTEU3> was down 0.6 percent.

Everybody is on a hair trigger here until we see what comes out of Sunday's EU finance ministers' meeting, said Mendelsohn. Everybody is getting everything second-hand so nobody knows what's going to happen.

The S&P 500 has struggled after reaching the top end of a two-month trading range at around the 1,230-1,250 level and progress on Europe's debt crisis is critical to breaking out of that range.

On the earnings front, American Express Co's third-quarter earnings beat expectations late on Wednesday, while eBay gave a cautious outlook for the rest of the year although third-quarter revenue came in line with Wall Street expectations.

EBay's shares fell 4.8 percent to $31.60 while American Express was thinly traded and flat at $46.15 in pre-market trade.

The Wall Street Journal reported Microsoft was working with Silver Lake Partners and the Canada Pension Plan Investment board on a joint bid for Yahoo.

Yahoo's stock rose 1.6 percent to $16.20 before the bell.

U.S. weekly jobless claims are due at 8:30 a.m., while the Philadelphia Federal Reserve Bank's October business activity survey and U.S. existing home sales for September are released at 10:00 a.m.

U.S. stocks fell on Wednesday on doubts about the euro zone's ability to come up with a comprehensive plan to solve its debt crisis and the Federal Reserve gave a weak economic outlook for the United States.

(Editing by Chizu Nomiyama)