US STOCKS-Wall St to open flat ahead of Fed statement; Facebook slides

* Facebook (NasdaqGS: FB - news) shares down as expenses seen rising

* Orbital Sciences (NYSE: ORB - news) falls after rocket explosion

* Futures: Dow up 20 pts, S&P flat, Nasdaq down 4 pts (Updates prices, adds comment)

By Rodrigo Campos

NEW YORK, Oct 29 (Reuters) - U.S. stocks were set to open little changed on Wednesday ahead of a statement from the U.S. Federal Reserve as it winds down its stimulus program, with a decline in Facebook keeping pressure on S&P 500 and Nasdaq futures.

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.

"Everybody is looking ahead to the FOMC statement in the afternoon. I'd expect we won't have a lot of movement before that," said Peter Jankovskis, co-chief investment officer at OakBrook Investments LLC in Lisle, Illinois.

"Not a lot is expected other than a confirmation that they eliminated QE and maybe we'll get additional guidance, hints on when they might start raising rates."

Facebook Inc shares fell 5.8 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.

S&P 500 e-mini futures were down less than a point and fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract, indicated a flat open. Dow Jones industrial average e-mini futures rose 20 points and Nasdaq 100 e-mini futures lost 4 points.

Hershey Co shares fell 2.8 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 (Berlin: DI6.BE - news) of American Realty Capital slid 20.4 percent after it said some of its previous financial statements were unreliable.

Orbital Sciences Corp shares fell 14.8 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. (Reporting by Rodrigo Campos; Editing by Lisa Von Ahn and Nick Zieminski)