"Companies involved in exploration and production—known as 'upstream operations'—are vulnerable simply because they've earmarked too much capital for production. While fracking has helped increase capacity, the cost of developing production capabilities isn't likely to be fully recovered," Rudolph-Shabinsky said.
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"The lower the price of oil goes, the more likely it is that companies will struggle to recover their costs," he said.
Following the OPEC's production policy decision, Russian oil tycoon Leonid Fedun, vice president and board member at the country's second-largest oil company OAO Lukoil, warned of a similar risk.
"In 2016, when OPEC completes this objective of cleaning up the American marginal market, the oil price will start growing again," Fedun said, as quoted by Bloomberg. "The shale boom is on a par with the dot-com boom. The strong players will remain, the weak ones will vanish," he said.
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John Kilduff, partner at Again Capital, a commodity investment firm that sees prices diving into the low-$50 area early next year, agreed highly leveraged shale producing companies are a risk to watch for.
However, he doesn't subscribe to the doomsday theory floating around that a wave of debt defaults by U.S. oil producing companies could cause another financial crisis a la 2008.
"I don't subscribe to that, but it is worth noting, and I am on the lookout for signs of real trouble."