* Crude falls after 4-day rally
* ADP employment falls short of expectations
* Merck down after earnings, Disney climbs
* Futures off: Dow 18 pts, S&P 6.25 pts, Nasdaq 14.5 pts (Adds ADP data, quote)
By Chuck Mikolajczak
NEW YORK, Feb 4 (Reuters) - U.S. stocks were poised to dip at the open on Wednesday, in the wake of a two-day rally for the S&P 500, as oil prices declined and labor market data disappointed.
The ADP National Employment Report showed private employers added 213,000 jobs in January, falling short of the median forecasts of analysts of 225,000 jobs.
Oil prices declined after a four-day rally of nearly 20 percent as a new build in U.S. crude stockpiles put a global glut back in focus. U.S. crude was down 3.3 percent to $51.32 and Brent was off 2.6 percent to $56.43. Contract driller Transocean fell 1.9 percent to $18.05 in premarket trade.
"Oil has been the big driver. We have seen oil moving strongly since last Friday and certainly the energy sector was leading the market higher," said Peter Jankovskis, co-chief investment officer at OakBrook Investments LLC in Lisle, Illinois.
"People may be taking a bit of a wait-and-see attitude here to see if oil drops further or if it holds where it is at."
Merck shares lost 2.2 percent to $59.70 before the opening bell after the drugmaker reported slightly disappointing fourth quarter sales and predicted 2015 earnings below analyst forecasts, citing the stronger dollar.
But fellow Dow component Disney gained 4.9 percent to $98.70 after quarterly profit topped Wall Street's estimates.
The S&P 500 has gained 2.8 percent over two sessions as oil prices bounced and on hopes of a Greek debt deal, although the index has been locked in a trading range of 1,972 to 2,093 since mid-December and is nearly flat since Dec. 31. Despite the tight range, equities have been more volatile in 2015, with the daily trading range in the index often double its average over the past year.
S&P 500 e-mini futures were down 6.25 points and fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract, indicated a lower open. Dow Jones industrial average e-mini futures fell 18 points and Nasdaq 100 e-mini futures lost 14.5 points.
Later in the session at 9:45 a.m. (1445 GMT), financial data firm Markit will release its final January reading on the services sector. At 10 a.m. (1500 GMT), the Institute for Supply Management will release its reading on the services sector.
Gilead Sciences shares dropped 7.5 percent to $99.20 in premarket. The drugmaker posted quarterly results and said it is offering steeper-than-expected discounts on its hepatitis C drugs to health insurers and other group payers who had complained about the price.
General Motors reported fourth-quarter earnings well above Wall Street expectations and said it plans to raise its quarterly dividend by 20 percent, sending shares up 4 percent to $35.35 in premarket.
Chipotle Mexican Grill slumped 6.1 percent to $682 in premarket after sales growth at established restaurants slowed in the fourth quarter and slightly missed Wall Street's estimate. (Reporting by Chuck Mikolajczak; Editing by Chizu Nomiyama and Nick Zieminski)