Oil producers are taking advantage of the rebound in crude markets to lock in protection against another slump. They increased their bets on falling prices to the highest level in 4 1/2 years as U.S. inventories of stored oil remained near an 87-year high, while a natural disaster in Canada and militant attacks in Africa curtailed output. Negative sentiment among the group expanded for a third consecutive week, the longest streak since February. Energy companies from EOG Resources Corp. to Chesapeake Energy Corp. used financial instruments such as futures, swaps and collars to guard against another fall in prices. West Texas Intermediate oil, the benchmark U.S. crude, has gained more than 75 percent since hitting a 12-year low in mid-February. “They’ve been getting more and more active in hedging ever since the first initial jump,” said John Kilduff, a partner at Again Capital LLC in New York. […]