For the past couple of years, traders have made rich profits from selling oil futures closing in on expiration and reinvesting the proceeds in later-dated contracts that carry lower prices. This strategy proliferated in recent years among exchange-traded and momentum-tracking funds seeking to exploit the market condition known as . The conditions that had made this crude oil trade so lucrative suddenly dried up. On Monday, Brent-crude futures that expire this month closed below the price of contracts that expire in March for the first time in almost a year-a situation known as contango; backwardation contango; inverted market inverted market; backwardation O backwardation; contango