Stock index futures rose slightly on Friday ahead of a speech from Federal Reserve Chairman Ben Bernanke and an estimate on second-quarter economic growth, which may offer clarity on how strongly a recovery is taking hold.

The second estimate of U.S. second-quarter gross domestic product will be released at 8:30 a.m. EDT. Economists expected an annualized rate of growth of 1.4 percent, down from 2.4 percent in the previous estimate.

Recent disappointing reports have pressured equities and underlined fears of a double-dip recession.

A weak GDP will make a double dip more likely, said James Dailey, portfolio manager at the Harrisburg, Pennsylvania-based TEAM Asset Strategy Fund. Dailey said a reading below 1 percent was certainly plausible.

Direct stimulus from the government has declined, and now we're going back to economic fundamentals, which are stressed with high unemployment and without income growth.

Bernanke will speak later Friday at a retreat for central bankers at Jackson Hole, Wyoming. He may discuss prospects for the world's biggest economy but isn't expected to offer any clues on whether the Fed will pump in more cash to keep the recovery going.

Some investors are hoping for a magic bullet from Bernanke, but I doubt the Fed is going to announce anything of any significance, Dailey said. I think something significant is coming, but it's too early for that now.

The Thomson Reuters/University of Michigan Surveys of Consumers' final August consumer sentiment index reading is due at 9:55 a.m. EDT. Economists look for a reading of 69.6, a repeat of the previous number.

S&P 500 futures rose 2.9 points and were slightly 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 gained 17 points, and Nasdaq 100 futures were up 8.5 points.

3PAR Inc
, the data storage company, accepted a $1.8 billion buyout offer from Dell Inc , even after Hewlett-Packard Co raised its own bid to $1.8 billion late Thursday. 3PAR shares gained 8.9 percent to $28.34 in premarket trading.

In other acquisition news, cybersecurity firm ArcSight Inc put itself up for sale, and possible buyers may include Oracle Corp , International Business Machines Corp, or HP, the Wall Street Journal reported. ArcSight shares rose 2.4 percent to $37.50 before the bell.

Luxury retailer Tiffany & Co reported higher quarterly profits and raised its full-year earnings forecast.

Boeing Co has pushed back delivery of its first 787 Dreamliner by several weeks to the middle of the first quarter of 2011 due to delays in a Rolls-Royce engine needed for final flight testing.

The Dow closed below 10,000 points on Thursday, the first time it ended below that psychologically important level since July 6.

(Editing by Jeffrey Benkoe)