US STOCKS-Futures little changed, Fed officials due to speak
* Fed officials, including Bullard, scheduled to speak
* Trading may get volatile due to "quadruple witching"
* Futures: Dow off 1 pts, S&P flat, Nasdaq up 4.3 pts
NEW YORK, Sept 20 (Reuters) - U.S. stock index futures were little changed as investors hoped that remarks by several senior Federal Reserve officials scheduled to speak on Friday would shed light on the Fed's recent surprise decision to keep its stimulus efforts intact.
* Trading could be volatile as Friday marks the "quadruple witching," when stock index futures, stock index options, stock options and single stock futures all expire on the same day. Trading increases as investors replace or repurchase existing contracts.
* Two days after an unexpected decision by the Federal Reserve to delay scaling back its massive monthly bond purchase program, four central bank officials are due to speak, and investors hope their remarks may contain signals on how much longer the Fed's stimulus will continue.
* Kansas City Federal Reserve Bank President Esther George is due to deliver a speech on the economy to the Shadow Open Market Committee in New York at 12:30 p.m. EDT (1630 GMT).
* Federal Reserve Governor Daniel Tarullo speaks on macroprudential regulation in New Haven, Connecticut at 12:40 p.m. EDT.
* St. Louis Federal Reserve Bank President James Bullard speaks on monetary policy to New York Association for Business Economics at 12:55 p.m. EDT.
* Minneapolis Federal Reserve Bank President Narayana Kocherlakota talks at a conference on risk in options prices in New York at 1:45 p.m. EDT.
* On Thursday, U.S. stocks retreated slightly as investors paused after the Federal Reserve's decision Wednesday to keep its stimulus intact sparked a rally that day which took the Dow and S&P 500 to record highs.
* S&P 500 futures were flat and in line with 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 fell 1 points, and Nasdaq 100 futures added 4.3 points.
* In company news, Microsoft Corp could be in the spotlight. Chief Executive Steve Ballmer has made an impassioned plea to investors at an annual meeting to support his vision of the world's largest software company as a unified devices and services powerhouse. He had said in August he plans to step down within 12 months. The stock was down 0.1 percent at $33.61 in premarket trading.