US STOCKS-Indexes set to open slightly lower as crude retreats
* Exxon, Chevron slide as crude gives up gains
* Pep Boys down after Bridgestone pulls out of buyout
* S&P 500 marginally positive for year
* Futures down: Dow 50 pts, S&P 5.5 pts, Nasdaq 8.5 pts (Adds details, updates prices)
By Abhiram Nandakumar
Dec 30 (Reuters) - U.S. stock indexes were set to open marginally lower on Wednesday as crude oil gave up Tuesday's gains after forecasts suggested winter in Europe and the United States would be short-lived.
Global stocks followed crude prices lower, as demand remains sluggish and supply continues unabated.
Shares of Exxon and Chevron were down about 1.3 percent in premarket trading.
The S&P 500 energy sector is down 22.68 percent for the year, easily the worst performer on the index, followed by an 8.72 percent decline in materials, caused by the rout in commodities. Continuación...