After several years of neglect, oil investors are again betting heavily on the price difference between two global benchmarks – Brent and U.S. crude futures – due to a push in Washington to impose a controversial import tax. At the start of this decade, the play on the spread between North Sea Brent and U.S. West Texas Intermediate (WTI) contracts futures earned traders and banks hundreds of millions of dollars, provided they played the high-stakes game right. This trade, nicknamed the “widowmaker” for its high level of risk, fell out favor about four years ago when the two contracts resumed moving in tandem, sharply reducing the spread volatility on which it depended. Then OPEC’s decision in November to cut crude output, hoping to reverse more than a year of steep […]