Oil prices rebounded on Friday as traders appeared to be closing out a recent raft of bearish bets. April turned out to be a bad month for oil, with stockpiles still growing at times despite widespread expectations that global output cuts would start causing them to drain. U.S. crude finished the month down 2.5%, causing back-to-back monthly losses for the first time since last summer. With both the trading week and month ending Friday, and the contracts for both gasoline and diesel expiring, many traders took the moment to recalibrate, analysts said. Oil markets had all had at most just two winning sessions in the past two weeks, and many of the traders who sold contracts during that time are likely to want to close out those positions to square their trading books, analysts said.