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Making fuel resilient by shrinking oil demand

There is potential trouble in the world's oil supply, former energy portfolio manager Nick Tiller told CNBC on Thursday.

"The oil market right now is probably as dicey as I've seen it my career," said Tiller, who noted instability in Libya, Iraq and Venezuela. "There's a lot of reason to be concerned about supply disruption in the oil markets right now."

Tiller, who left SAC Capital Advisors last fall amid investigations of the hedge fund, made his comments on CNBC's "Halftime Report,"

He said he left the hedge fund last fall to start Sustainable America, a charity focused on reducing the demand for oil through the use of natural gas, biofuels, ethanol and conservation.

Former SAC energy trader talks culture

SAC Capital, which settled an insider trading case with the U.S. Department of Justice in November, was renamed Point72 Asset Management earlier this month.

Tiller said that has "a lot of respect" for founder Steve Cohen and denied a characterization of the company as lawless.

"That's not the culture of SAC as I know it. I worked there for a long time, and I can tell you that we were all expected to obey the law," he said. "And the people I know at SAC, the people who I worked with, are honest people who do their jobs with integrity."

By CNBC's Bruno J. Navarro.