* ADP report and other data to provide clues on Fed move
* Concern Fed may slow stimulus weighs on world markets
* Futures off: S&P 8 pts; Dow 64 pts; Nasdaq 12.75 pts
U.S. stock index futures fell on Wednesday, ahead of a slew of economic reports which includes data on private sector jobs, amid lingering concerns that the Federal Reserve may slow the pace of its economic stimulus program.
Among data due are a private sector jobs report, factory orders and the ISM non-manufacturing index. Investors will peruse these for clues on the state of the economy and the Fed's future moves. The Federal Reserve's beige book is also on tap.
"Volatility has been rising due to increasing skepticism about the market's rally," said Peter Cardillo, chief market economist at Rockwell Global Capital in New York.
"It's all about the ADP and the beige book today. If the consensus is for stronger growth ahead for the economy, that will increase the Fed fear factor."
S&P 500 futures fell 8 points and were below fair value on Wednesday, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures lost 64 points and Nasdaq 100 futures fell 12.75 points.
The ADP private-sector payroll report is due at 8:15 a.m. EDT (1215 GMT). Analysts in a Reuters survey expect a reading of 165,000 in May versus 119,000 in April.
Japan's Nikkei share average sagged to a two-month low Wednesday, weighing down global shares, after investors failed to be enthused by a speech by Prime Minister Shinzo Abe on his growth strategy to revive the world's third-largest economy.
European shares fell on concerns about a possible tapering of U.S economic stimulus measures, while a broker downgrade knocked back supermarket retailer Carrefour.
U.S. productivity and costs data is due at 8:30 a.m. EDT, while both factory orders data and the ISM non-manufacturing index are due at 10:00 a.m. EDT.
The Fed's beige book, a report on economic conditions of the Federal Open Market Committee, is due at 2:00 p.m. EDT.
American International Group Inc said Tuesday a proposed $8.5 billion settlement between Bank of America Corp BAC.N and investors of Countrywide Financial Corp mortgage-backed securities was not big enough.
U.S. stocks ended lower on Tuesday, resuming a recent decline as investors sold growth-oriented sectors on speculation the Federal Reserve may slow the pace of its economic stimulus.
The decline followed comments from Kansas City Federal Reserve Bank President Esther George, who urged the Fed to ease off its aggressive bond purchases, saying this would help wean financial markets off their dependence on ultra-easy money from the U.S. central bank.