Israeli oil refiner, Delek US (NYSE: DK) has been on a tear these past couple days. Oil refiner in Israel? Well, as the joke goes, Moses didn't actually make the wrong turn at the Red Sea. Well, kind of...

Delek US is actually the U.S. arm of an Israeli conglomerate operating in three segments: refining, marketing and retail. The refining business runs at a distillation rate of 60,000 barrels per day. Delek's marketing segment sells refined products on a wholesale basis in west Texas. Its retail segment sells gas as well as operates convenience stores through a network of over 400 company-operated retail fuel and convenience stores.

Citigroup upgraded Delek US earlier this week, pushing the shares up about 10%. Looking under the hood of the upgrade, the Citigroup analyst cited in a note early this week a recently disclosed acquisition of a 34.6% equity stake in Lion Oil toward the end of the third quarter. As the public learns more about Delek's plans, we may see this position serve as a catalyst for the shares in the next couple of quarters.