* Services sector grows in April, fastest pace in 8 months
* JPMorgan leads banks lower after trading revenue warning
* Pfizer's revenue below expectations, shares fall
* Indexes: Dow flat, S&P up 0.07 pct, Nasdaq up 0.11 pct (Updates to midday, changes byline)
NEW YORK, May 5 (Reuters) - U.S. stocks were little changed on Monday, as upbeat economic data was offset by concerns over an escalation of tensions between Ukraine and pro-Russia separatists.
Equities initially opened lower, weighed by geopolitical events as Ukrainian forces were ambushed by separatists on Monday, triggering heavy fighting on the outskirts of the rebel stronghold of Slaviansk, a day after a Ukrainian police station in Odessa was stormed.
But equities rebounded after the Institute for Supply Management said its services sector index rose to 55.2 in April, the fastest pace in eight months, from 53.1 in March, topping expectations for a read of 54.1.
"It's more confirmation the economy is strengthening and we are headed for stronger growth," said Peter Cardillo, chief market economist at Rockwell Global Capital in New York.
"Unfortunately, we had those headlines out of Ukraine where the situation seems to be escalating but once the market realized the economy is doing better, we saw the snapback."
Bank shares were under pressure, weighed by a 2.1 percent drop in JPMorgan Chase to $54.43. 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 0.5 percent.
Energy shares were among the best performers, with the S&P energy index up 0.5 percent.
Occidental Petroleum, the fourth-largest U.S. oil and gas company, reported a better-than-expected profit for the third straight quarter, helped by higher prices for crude oil and natural gas in the United States. Shares rose 0.8 percent to $95.17.
The Dow Jones industrial average rose just 0.77 point to 16,513.66, the S&P 500 gained 1.34 points, or 0.07 percent, to 1,882.48 and the Nasdaq Composite added 4.337 points, or 0.11 percent, to 4,128.235.
Pfizer Inc also lost ground as the biggest U.S. drugmaker reported revenues well below analysts' expectations. Shares fell 2.5 percent to $29.99.
Target Corp shares fell 3 percent to $60.16 after news that Chief Executive and Chairman Gregg Steinhafel will leave the company in the wake of a data breach late last year that hurt profits, shook customer confidence in the No. 3 U.S. retailer and prompted congressional hearings.
German aircraft seating maker Recaro said it was studying the possibility of buying assets from B/E Aerospace after the U.S. company announced a surprise review. B/E Aerospace shares jumped 11 percent to $98.84. (Editing by Bernadette Baum)