In June,...BP was stripped from the Dow Jones Sustainability Index. The index, which tracks “sustainability leaders” in industry worldwide, determined that the [Gulf of Mexico] oil spill was an “extraordinary event” that merited BP’s removal. This week, Dow Jones unveiled its choice for filling the BP vacancy...: Halliburton...Some market observers found the selection puzzling, however. Halliburton, after all, was deeply involved in the BP drilling operation that ultimately caused an estimated 4.4 million barrels of oil to spill into the Gulf of Mexico. The company remains under investigation by the Justice Department for its role in the disaster, and could still face civil or even criminal sanctions...Also...on the sustainability index was Nalco, the manufacturer of the oil dispersant Corexit. Nearly two million gallons of the chemical were sprayed on or under the surface of the gulf by BP...to break up the oil gushing from its well. Debate has unfolded over the environmental impact of dispersant in the gulf.