* ADP employment report comes in below expectations
* Zynga rallies, to offer casino games in Britain
* Dow down 5 pts, S&P up 0.4 pts, Nasdaq up 1.75 pt
By Ryan Vlastelica
NEW YORK, April 3 (Reuters) - U.S. stock index futures were poised to open little changed on Wednesday as investors brushed off a weak reading on private sector employment and the S&P 500 remained within striking distance of an all-time intraday high.
Investors expect market movements to be slight ahead of the release Friday of the closely watched nonfarm payrolls report, with few major trading catalysts before then. The S&P has gained less than 0.1 percent so far this week.
Futures were little changed despite the latest ADP National Employment Report, which showed 158,000 private sector jobs were added in March, far less than economists had expected. The February report was revised upward by 39,000.
"People aren't worried about employment compared to the overall macro outlook, and they have a general idea that the economy is improving," said Wayne Kaufman, chief market analyst at John Thomas Financial in New York. "That should allow us to hold firm."
The S&P has been near its record level of 1,576.09 for the past several sessions, and inched to within three points of it on Tuesday before pulling back, though it ended at a new closing high.
The March read for the Institute for Supply Management's services index, due at 10:00 a.m. EDT (1400 GMT), is seen at 55.8, down from 56.0 in the previous month.
While data has largely been positive and helped to propel the equity market in the first quarter, a few disappointments have made investors cautious. The ISM manufacturing index on Monday came in below expectations.
"Some data has indicated softening, but things should remain quiet until Friday," Kaufman said.
S&P 500 futures rose 0.4 point, less than 0.1 percent, though it was above 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 slipped 5 points and Nasdaq 100 futures rose 1.75 point.
The S&P 500 has advanced more than 10 percent this year, and last week, broke above its 2007 closing high, a level it exceeded on Tuesday. The Dow first broke above its 2007 record on March 5.
In company news, Zynga Inc surged 11 percent to $3.40 in premarket trading after the company said it would begin offering poker and casino-style games in Britain in partnership with Bwin.party Digital Entertainment.
ConAgra Foods Inc fell 1.6 percent to $34.98 before the bell. The company reported third-quarter earnings that fell 57 percent even as revenue grew.
Monsanto Co rose 0.4 percent to $104 in premarket trading after reporting earnings that beat expectations and raising its full-year profit forecast.
Verizon Communications Inc ruled out a full takeover of Vodafone , turning the focus yet again to whether the two telecom giants can do a deal over their Verizon Wireless joint venture.
U.S.-listed shares of Vodafone fell 2.9 percent to $28.56 in premarket trading while Dow component Verizon was off 0.4 percent at $49.30.
Issues in the euro zone will continue to be in focus a day after Cyprus concluded a bailout deal. The plan, which still requires ratification, would mean the country receives a 10 billion euro loan and that it has until 2018 to carry out measures to shore up its finances. The country's finance minister resigned after concluding the deal.
While investors have largely used any market decline as a buying opportunity, the situation in Cyprus has been a major source of market uncertainty in recent weeks.
U.S. stocks rose on Tuesday, lifted by healthcare stocks, after a government decision on payment rates. Strong factory orders data also added to the positive tone.