* Facebook shares down as expenses seen rising
* Orbital Sciences falls after rocket explosion
* Futures: Dow up 10 pts, S&P off 2 pts, Nasdaq down 7.5 pts (Updates prices, adds byline)
By Rodrigo Campos
NEW YORK, Oct 29 (Reuters) - U.S. stock index futures were mixed on Wednesday, with S&P 500 and Nasdaq futures weighed by a sharp decline in Facebook shares, and ahead of a statement from the U.S. Federal Reserve as it winds down its stimulus program.
* In an otherwise data-light session, the Fed is likely to announce that it will no longer add to its holdings of Treasury bonds and mortgage-backed securities, effectively ending a program that at its peak pumped $85 billion a month into the financial system.
* The Fed’s cash injection is widely seen as a pillar of the current multiyear bull market in equities, and earnings are expected to support any further advances. So far this reporting season, 73.5 percent of S&P 500 companies have exceeded profit expectations. In a typical quarter since 1994, 63 percent of companies beat estimates, according to Thomson Reuters data.
* Facebook Inc shares fell 6.5 percent in premarket trading the day after the social network announced an increase in spending in 2015 and projected a slowdown in revenue growth this quarter.
* Hershey Co shares fell 4.7 percent after the chocolate maker cut its full-year earnings and revenue growth forecasts, citing higher dairy prices, a stronger dollar and weak sales growth in some markets.
* Shares of American Realty Capital slid 14 percent after it said some of its previous financial statements were unreliable.
* Orbital Sciences Corp shares fell 14.4 percent a day after its unmanned rocket exploded seconds after liftoff from a commercial launch pad in Virginia, marking the first accident since NASA turned to private operators to deliver cargo to the International Space Station.
Futures snapshot at 8:17 EDT (1217 GMT):
* S&P 500 e-minis were falling 2 points, or 0.1 percent, with 162,100 contracts changing hands.
* Nasdaq 100 e-minis were down 7.5 points, or 0.18 percent, in volume of 29,675 contracts.
* Dow e-minis were up 10 points, or 0.06 percent, with 20,000 contracts changing hands. (Reporting by Rodrigo Campos; Editing by Lisa Von Ahn)