I've been doing this for 23 years, and I wasn't entirely aware we could trade negative," he says. "I was far from alone." Mr Luckock thought many in the industry had not understood how low oil prices could go, exacerbating the crash. Rumours are now swirling around the oil world. Among the traders' chatter, there is one persistent motif: Trafigura hit the jackpot as prices plummeted. "They've done a roaring trade this week," says one industry source.