Stock futures imply flat open; energy on track for big drop

Stock futures imply flat open; energy on track for big drop, U.S. stock index futures pointed to a flat open on Friday, as the market's recent upward bias looked to continue in a holiday-shortened session, though energy shares saw heavy pressure as crude oil tumbled to a four-year low.

Wall Street was closed for the U.S. Thanksgiving holiday on Thursday and will shut three hours earlier on Friday. Trading volatility could spike since many market participants were extending the holiday.

U.S. crude futures CLc1 slumped 6 percent to $69.26 per barrel. It was the biggest one-day drop for crude since September 2011, and the decline brought prices to their lowest since 2010. On Thursday, OPEC decided not to cut output, which could leave oil markets heavily oversupplied.

Energy shares have been under pressure throughout 2014 as crude prices have slid more than 30 percent from a recent closing high. The S&P energy sector .SPNY is the only S&P 500 industry group to be lower for the year, down 4.3 percent.

The Energy Select Sector SPDR exchange-traded fund (XLE.P) fell 4 percent to $81.88 in pre-market trading. Exxon Mobil Corp (XOM.N) lost 3.5 percent to $91.20 while Chevron Corp (CVX.N) fell 3.4 percent to $111.21; both stocks are Dow components. Halliburton Co (HAL.N) lost 5.3 percent to $44.81.

The weakness in oil could be a boon for the holiday shopping season, with lower gas prices possibly sparking increased consumer spending.

The decline in oil boosted airline shares ahead of the market open. American Airlines Group Inc (AAL.O) rose 5.4 percent to $47.40 before the bell, while JetBlue Airways Corp (JBLU.O) was up 5.4 percent to $14.33. Delta Air Lines Inc (DAL.N) jumped 4.9 percent to $46.40.

Despite the energy weakness, major indexes could eke out a sixth straight weekly advance. For the week so far, the Dow is up 0.1 percent and the S&P is up 0.5 percent. The Nasdaq, which counts few energy names among its major components, is up 1.6 percent this week.

Equities have been strong of late, with the Dow and S&P 500 both closing at records on Wednesday. Recent gains have been fueled by actions from central banks around the world, as well as strong economic data and corporate results.