“Widening refining margins are favorable for refiner stock performance. The chart above shows that refiners (as measured by the S&P 500 Oil & Gas Refining & Marketing Index) have outperformed the energy sector as a whole (S&P 500 Energy Index) over the past 10 years when crack spreads are wide or widening, while falling crack spreads have been a drag on the relative performance of refining shares. That’s because cheaper fuel prices help to stimulate product demand, while ample supplies of oil help lower the cost of production,” according to PowerShares. [Contrarian ETF Ideas for 2015]

The $106.1 million PXE features four refiners among its top 10 holdings, including Valero (NYSE: VLO) and Phillips 66 (NYSE: PSX), two of this year’s stronger energy names.

PowerShares Dynamic Energy Exploration & Production Portfolio