Oil investors who amassed a $6 billion long position in exchange traded funds, occupying as much as a third of the U.S. futures market, are now racing for the exit at a near record pace. Outflows from four of the largest oil-specific exchange traded funds, including the largest U.S. Oil Fund (USO), reached $338 million in two weeks to April 8, according to data from ThomsonReuters Lipper.