Wrong-Way Oil Bets Slam an Energy Firm

The rapid fall of energy company SemGroup LP has startled participants in the oil markets, left creditors struggling to understand how the company's trading went wrong and attracted the attention of federal authorities.

Until now a little-known, though large, closely held partnership in Tulsa, Okla., SemGroup transports, stores and distributes crude oil and refined products. It filed for bankruptcy protection this week after losing more than $2.4 billion on energy contracts it had entered into. Exactly what drove the company to that fate remains unclear, but clues have started to emerge amid court hearings and other ripples from the implosion.