U.S. stock index futures pointed to a lower open on Friday after Chevron warned about second-quarter earnings, raising the specter of a weaker-than-expected second-half economic recovery and anemic corporate profits.

After the bell Thursday, Chevron Corp said second-quarter earnings would be hit by a sharp decline in U.S. refining margins and that any benefits from higher oil prices would be largely offset by a weaker dollar.

Stocks are likely to be pushed and pulled as major companies release financial scorecards and investors focus on the corporate outlook for the rest of the year. Earlier in the week, Alcoa Inc posted a better-than-expected loss Wednesday, providing short-term relief.

Optimism about a burgeoning economic recovery has propelled the broad S&P 500 up by as much as 40 percent from March's 12-year lows, but investors are reassessing how strong a recovery might be after the worst financial crisis since the Great Depression.

It's pretty clear that the green shoots thesis, which a lot of optimists were hoping would have some sway, is a nonstarter, said Barry Ritholtz, director of equity research at Fusion IQ in New York.

Now people are adapting to a more realistic view of the economy, which is ongoing weakness for the foreseeable future and everything that means for corporate earnings.

Economic data on tap includes the preliminary reading for July's Reuters/University of Michigan survey of consumer sentiment, due at 9:55 a.m. EDT. The data is expected to come in at 70.5, down from 70.8 in June, according to the average forecast of economists polled by Reuters.

S&P 500 futures fell 7.50 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 lost 62 points, and Nasdaq 100 futures gave up 7.25 points.

After a whirlwind 40-day reorganization, General Motors Corp prepared to exit bankruptcy Friday, saying it was a leaner and meaner automaker ready to win back American consumers and pay back taxpayers.

Ritholtz said the speed with which GM emerges from bankruptcy could provide a viable alternative for saving companies without taxpayer bailouts.

Technology shares may get a boost after Goldman Sachs upgraded both the software and hardware sectors to attractive.

On Thursday, stocks edged higher as investors bought beaten-down technology and commodity shares and a positive broker comment on Goldman boosted the financial sector.

(Reporting by Leah Schnurr; editing by Jeffrey Benkoe)