U.S. stock index futures fell slightly on Wednesday as traders awaited key data on the labor market and services sector.

* U.S. data is being closely watched after a weak reading in the factory sector on Monday sent Wall Street into a tailspin and triggered a global equities selloff.

* ADP will publish its January report on private job creation at 8:15 a.m. EST. Economists surveyed by Reuters expect 180,000 jobs were created last month, down from 238,000 in December.

* At 10:00 a.m. (1500 GMT) ISM will report its non-manufacturing PMI for January. Economists expect a slight acceleration in the pace of growth to a reading of 53.7 from 53 in December.

* The limp data earlier in the week added to concerns about growth in China and over the outlook for some emerging market economies. A recent rout in emerging currencies spurred some central banks to act, pressuring bond and stock holdings and luring investors into assets perceived as relatively safe, like the yen, and U.S. and German government debt.

* U.S. stocks rebounded on Tuesday, buoyed by encouraging earnings, as the market attempted to steady in the wake of its largest selloff in months on Monday.

* S&P 500 e-mini futures fell 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 7 points and Nasdaq 100 futures lost 3 points.

* Merck (MRK.N) shares rose 2.9 percent in premarket trading after the Dow component reported sales and profit that just missed analysts' estimates.

* Shares of Tableau Software (DATA.N) jumped 14 percent in premarket trading after the data analysis software maker forecast better-than-expected revenue for this quarter and reported results that handily beat analysts' estimates.

* CVS Caremark Corp (CVS.N) said on Wednesday it would stop selling tobacco products at its 7,600 stores by October, becoming the first U.S. drugstore chain to take cigarettes off the shelf. Its shares fell 1.7 percent in light premarket trading.

(This story was corrected to fix time of release of ADP data to 8:15 a.m. from 8:30 a.m.)