Just as West Texas Intermediate futures, the benchmark U.S. crude oil contract, have ascended to the highest levels since December, rising volatility is chasing investors from some oil exchange traded products.

Annualized 90-day volatility for the S&P GSCI Crude Oil Total Return Index, which serves as the underlying benchmark for the iPath S&P GSCI Crude Oil Total Return Index ETN (NYSEArca: OIL), is at its highest levels since the late stages of the global financial crisis in early 2009, according to S&P Dow Jones Indexology.

That volatility spike could be one reason investors are deparing oil ETPs just as the getting is good. Since the start of April, investors have yanked almost $498 million from the United States Oil Fund (NYSEArca: USO). By doing do that, those that departed USO have missed out on a rally that has seen the fund jump more than 12% this month. [Commodity ETFs Starting to Rebound]

Perhaps not surprisingly, investors have also left leveraged oil ETPs in droves. For example, the double-leveraged ProShares Ultra Bloomberg Crude Oil (NYSEArca: UCO) and the triple-leveraged VelocityShares Daily 3x Long Crude ETN (NYSEArca: UWTI) have lost a combined $465 million this month. Over the past month, UWTI, which attempts to deliver three times the returns of the aforementioned S&P index, has surged 52.3%. [Winning With Leveraged Oil ETFs]

“Despite supportive data from the China Association of Automobile Manufacturers that showed a 9% year-over-year gain in new vehicle sales in the first two months of 2015, the IEA reported heightened stock-builds likely from extra import flows but with an ailing industrial backdrop. That ailing backdrop seems to be weak enough now to possibly cause Chinese stimulus to be the catalyst of an oil rebound,” said S&P Dow Jones Indices Global Head of Commodities Jodie Gunzberg in a note.

Not all oil ETPs have bled assets as volatility has soared. The United States 12 Month Oil Fund (NYSEArca: USL) has added almost $11 million in new assets this month. USL is less volatile than USO because its net asset value reflect changes of the price of WTI Crude Oil delivered to Cushing Oklahoma as measured by changes in percentage terms of the price of an average of the next 12 month’s WTI. USL is up 10.6% this month.