Investors purchased small volumes of petroleum last week, after exceptionally heavy sales the week before, squaring up short positions after an unusually sudden and steep pull back in prices on recession fears. Hedge funds and other money managers purchased the equivalent of 8 million barrels in the six most important petroleum futures and options contracts in the week to July 12. That came after cumulative sales of 201 million barrels over the previous four weeks, culminating in sales of 110 million in the week to July 5, according to ICE Futures Europe and the U.S. Commodity Futures Trading Commission.