Looking ahead, investors will wait for further cues from other major players in the field. Halliburton Co. (NYSE: HAL) and Baker Hughes (NYSE: BHI), which are set to merge, will report third quarter results Monday and Wednesday, respectively.

HAL makes up 12.6% of OIH, 9.0% of IEZ, 2.7% of XES and 4.9% of PXJ. BHI makes up 8.2% of OIH, 7.5% of IEZ, 2.7% of XES and 5.0% of PXJ.

For those seeking a hedge against further weakness in the energy sector, the ProShares Short Oil & Gas (NYSEArca: DDG) tries to reflect the inverse, or -100%, daily performance of the Dow Jones U.S. Oil & Gas Index. The UltraShort Oil & Gas ProShares (NYSEArca: DUG) takes two times the inverse, or -200%, daily performance of the Dow Jones U.S. Oil & Gas Index. The Direxion Daily Energy Bear 3X Shares (NYSEArca: ERY) reflects three times the inverse, or -300%, daily performance of the energy select sector index. Moreover, the recently launched Direxion Daily S&P Oil & Gas Exploration & Production Bear Shares (NYSEArca: DRIP) takes the -3x, or -300%, daily performance of the S&P Oil & Gas Exploration & Production Select Industry Index.

Market Vectors Oil Service ETF

For more information on the energy sector, visit our energy category.

Max Chen contributed to this article.