* Futures off: Dow 25 pts, S&P 3.5 pts, Nasdaq 5.5 pts (Updates prices, adds pending data)
By Rodrigo Campos
NEW YORK, Jan 5 (Reuters) - U.S. stock index futures fell on Monday as volume returned to markets after the New Year holiday, with energy shares sliding again as crude prices fell to fresh 5-1/2 year lows.
* Crude oil futures prices dropped to their lowest since May 2009 amid a global supply glut and lackluster demand. Russia’s oil output hit a post-Soviet high last year, and Iraq’s oil exports in December were at the highest since 1980.
* Oil and other commodities are likely to be pressured further by the strength in the U.S. dollar. A measure of the greenback against a basket of major currencies hit its highest since December 2005.
* An exchange-traded fund that tracks S&P 500 energy stocks was down 1.2 percent in premarket trading. The S&P 500 energy sector fell almost 20 percent over the last two quarters of 2014.
* Shares of Cempra Inc jumped near 25 percent after it moved closer to approval of its lead antibiotic, solithromycin, after an oral version of the potential blockbuster met the main goal in a late-stage trial.
* A gauge of economic activity in the New York area is due at 9:45 a.m. (1445 GMT). Data on U.S. car and truck sales is expected throughout the day.
* Concerns over Greece’s future in the euro zone and a sharp decline in commodities stocks triggered by lower crude oil and metals prices kept European equities under pressure.
Futures snapshot at 8:04 a.m. (1304 GMT):
* S&P 500 e-minis were down 3.5 points, or 0.17 percent, with 152,522 contracts changing hands.
* Nasdaq 100 e-minis were down 5.5 points, or 0.13 percent, in volume of 26,812 contracts.
* Dow e-minis were down 25 points, or 0.14 percent, with 25,291 contracts changing hands. (Editing by Bernadette Baum and Nick Zieminski)