Stock index futures slipped on Wednesday, ahead of data on the jobs market, as jitters over the pace of the economic recovery prompted investors to lock in profits.

Global shares and the U.S. dollar were pressured by talk that recent weak economic data could prompt the Federal Reserve to start a new round of Treasuries purchases to pump funds into the economy. The greenback earlier neared a 15-year low against the yen.

Data on tap includes the ADP Employer Services report for July, due at 8:15 a.m. EDT, and the ISM nonmanufacturing index for the same month, coming at 10 a.m.

ADP is expected to show private employers added 40,000 jobs, compared with 13,000 the month before, while ISM is seen coming in at 53.0 versus 53.8 in the previous month, according to a Reuters poll.

Futures have been in a range all morning. We're waiting with bated breath for what ADP has to say, said Jamie Cox, managing partner of Harris Financial Group in Colonial Heights, Virginia.

S&P 500 futures slipped 3.3 points and were below 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 20 points, and Nasdaq 100 futures dipped 4.25 points.

The ADP report is often a harbinger of the monthly nonfarm payrolls figure, which is due Friday. The report is expected to show the economy lost 65,000 jobs, compared with a loss of 125,000 jobs the month before, while the unemployment rate is expected to edge up to 9.6 percent from 9.5 percent.

Interestingly enough, ADP has really been spot on with its analysis in the last couple months, so you're going to get a clean early look at Friday's jobs number, Cox said.

A fresh round of corporate earnings could lend support to the market. Electronic Arts Inc jumped 5.1 percent to $17 in premarket trade, a day after the video game publisher reported better-than-expected revenue.

Sirius XM Radio Inc's revenue topped estimates, while Time Warner Inc posted its highest growth rate in two years. Sirius shares jumped 5 percent at $1.06.

Stocks slipped Tuesday after disappointing corporate results and data on consumer spending and housing.

Even so, the S&P 500 held above its 200-day moving average of around 1,114, a potential signal that the market's strength remains intact. The index closed just below the 1,121 mark, a resistance level that represents the midpoint between the historic high reached in October 2007 and the 12-year closing low hit in March 2009.

Wall Street has been consolidating gains following a nearly 7 percent advance in July, the best month in a year.

(Editing by Jeffrey Benkoe)