* Services sector grows in April, fastest pace in 8 months
* JPMorgan leads banks lower after trading revenue warning
* Apple shares rise above $600
* Dow up 0.1 pct, S&P up 0.2 pct, Nasdaq up 0.3 pct (Updates to close)
By Caroline Valetkevitch
NEW YORK, May 5 (Reuters) - U.S. stocks ended slightly higher as data showed strength in the services sector and Apple shares rose above $600 for the first time since 2012.
Limiting the day's gains, however, were concerns over an escalation of tensions between Ukraine and pro-Russia separatists. Ukrainian forces were ambushed by separatists, triggering heavy fighting on the outskirts of the rebel stronghold of Slaviansk, a day after a Ukrainian police station in Odessa was stormed.
The Institute for Supply Management said its services sector index rose in April, hitting the fastest pace in eight months and topping expectations. It was the latest report to offer some upbeat news on the economy, which was hit by an unusually harsh winter.
"We shook off a lot of the morning jitters, and the ISM services came out and showed pretty good growth, and that obviously brought back some buyers," said Ryan Detrick, senior technical strategist at Schaeffer's Investment Research in Cincinnati, Ohio.
Apple shares, up 1.4 percent at $600.96, led both the S&P 500 and Nasdaq higher. Late in the session, the stock rose above $600 and also closed above the key level for the first time since Oct. 26 2012.
The Dow Jones industrial average rose 17.66 points or 0.11 percent, to 16,530.55, the S&P 500 gained 3.52 points or 0.19 percent, to 1,884.66 and the Nasdaq Composite added 14.158 points or 0.34 percent, to 4,138.055.
On the downside, shares of JPMorgan Chase fell 2.4 percent to $54.22, the biggest drag on the S&P 500. The bank said late on Friday it expects second-quarter revenue from bond and equity trading to decline by about 20 percent from a year earlier. The S&P financial index fell 0.4 percent.
Shares of Fannie Mae and Freddie Mac gained after activist investor William Ackman recommended the shares of mortgage finance giants during the Sohn Investment Conference in New York. Fannie was up 3 percent at $4.10 while Freddie was up 6.3 percent at $4.23.
Pfizer Inc shares fell 2.6 percent to $29.96 after gaining last week. The biggest U.S. drugmaker reported revenues well below analysts' expectations. (Editing by Bernadette Baum and Nick Zieminski)