* EPL Oil to be acquired by Energy XXI for $2.3 bln
* Express slumps after outlook
* Copper drops to lowest level in nearly four years
* Futures down: Dow 46 pts, S&P 6.25 pts, Nasdaq 13.25 pts
By Chuck Mikolajczak
NEW YORK, March 12 (Reuters) - U.S. stocks were poised to fall at the open, putting the S&P 500 on track for a third straight decline, as concerns grew over the strength of China's economy.
* London copper, seen as a proxy for China's economic health, fell for a fourth day to its lowest level since July 2010. Recent China data has suggested signs of economic slowing, while the country's first-ever bond default last week has increased concerns financing deals that use the industrial metal as collateral could unravel.
* Geopolitical issues also continue to be monitored by investors as earnings season has drawn to a close and amid a light economic calendar this week, leaving investors without a catalyst to push the benchmark S&P index higher after its most recent record close on March 7.
* Ukraine's government appealed for Western help on Tuesday to stop Moscow annexing Crimea but the Black Sea peninsula, overrun by Russian troops, seemed fixed on a course that could formalize rule from Moscow within days.
* EU member states have agreed the wording of sanctions on Russia, including travel restrictions and asset freezes against those responsible for violating the sovereignty of Ukraine, according to a draft document seen by Reuters.
* S&P 500 e-mini futures fell 6.25 points and were below 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 lost 46 points and Nasdaq 100 futures declined 13.25 points.
* EPL Oil & Gas Inc jumped 29.9 percent to $37.81 in premarket trading after the company agreed to be acquired by larger rival Energy XXI Ltd for $2.3 billion, including debt.
* Express Inc dropped 11.9 percent to $16.07 in premarket trading after the apparel retailer reported fourth-quarter earnings and forecast a profit for the current quarter that fell far short of analyst expectations.
* Oxigene Inc surged 127.3 percent to $5.50 before the opening bell after the company said its experimental drug Zybrestat combined with Roche's cancer drug Avastin significantly slowed progression of recurrent ovarian cancer better than Avastin alone in a midstage clinical trial.
* Geron Corp plunged 60.9 percent to $1.72 after the company said the U.S. Food and Drug Administration ordered a halt to trials of its cancer drug imetelstat over concerns about potential liver damage.