Here are a few snips from an explosive article in Forbes magazine:

When oil prices spiked last summer to $147 a barrel, the biggest corporate casualty was oil pipeline giant Semgroup Holdings, a $14 billion (sales) private firm in Tulsa, Okla. It had racked up $2.4 billion in trading losses betting that oil prices would go down.... With the credit crunch eliminating any hope of meeting a $500 million margin call, Semgroup filed for bankruptcy on July 22.

But now some of the people involved in cleaning up the financial mess are suggesting that Semgroup's collapse was more than just bad judgment and worse timing. There is evidence of a malevolent hand at work: oil price manipulation by traders orchestrating a short squeeze to push up the price of West Texas Intermediate crude to the point that it would generate fatal losses in Semgroup's accounts.
....
[N]umerous people familiar with the events insist that Citibank, Merrill Lynch and especially Goldman Sachs had knowledge about Semgroup's trading positions from their vetting of an ill-fated $1.5 billion private placement deal last spring. "Nothing's been proven, but if somebody has your book and knows every trade, it would not be difficult to bet against that book and put the company into a tremendous liquidity squeeze"....

The entire article is definitely worth a read. In 2008 there was tremendous market manipulation. Hoocudanode?