U.S. stock index futures pointed to a flat open on Wednesday, after shares hit a 10-week low the previous session, as anxious investors awaited the start of the quarterly earnings season.

After a rally that took the S&P 500 index up 40 percent from 12-year lows in early March, traders are looking for hard evidence that the economy will rebound from a deep recession.

But corporate earnings are seen to be weak. Alcoa Inc , the first Dow component to report earnings, is expected to post its third consecutive quarterly loss after markets close on falling demand for aluminum.

The economy's weakness could harm market sentiment and keep investors on the sidelines despite available bargains after Tuesday's 2 percent drop.

We're definitely having trouble rallying back from yesterday's losses. There is just very little potential positive news coming out right now, said Rick Meckler, president of LibertyView Capital Management in New York.

You're really going to have to discount that earnings are unlikely to provide good news throughout the whole period, he added. Perhaps the most optimistic view one could take is maybe you'll get some guidance things have bottomed.

S&P 500 futures fell 0.9 points but 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 dropped 13 points, and Nasdaq 100 futures rose 1 points.

In the technology sector, Google Inc plans an attack on Microsoft Corp's core business by taking on the software giant's Windows operating system for personal computers. Google said Tuesday it will launch a new operating system in the second half of 2010.

Google shares edged up before the market open, while Microsoft fell slightly.

Shares of Family Dollar Stores Inc rose more than 8 percent to above $30 in early electronic trading after the discount retailer reported that third-quarter profit beat expectations.

Leaders of the Group of Eight richest nations and the major developing powers are gathering for a three-day summit in Italy. They are expected to agree the world's economy is still too weak to remove stimulus measures.

New York crude futures fell below $62 per barrel after topping $73 in late June -- a slide that could pressure shares in the energy sector.

On the data front, the U.S. Federal Reserve is due to issue May consumer credit figures at 3 p.m. EDT. Economists surveyed by Reuters forecast consumer credit falling $9.5 billion versus a $15.68 billion decrease in April.

Shares of Amgen Inc shot up more than 16 percent premarket, one day after the biotechnology company said its experimental osteoporosis drug reduced and delayed serious bone complications among patients with advanced breast cancer.

U.S. stocks fell to their lowest level in 10 weeks on Tuesday as talk of a second government stimulus plan heightened fears that the economy was not yet on the path to recovery and corporate earnings for the second quarter would be weak.

(Reporting by Rodrigo Campos; additional reporting by Leah Schnurr; editing by Jeffrey Benkoe)