Oil is one of the fourth-quarter's best-performing asset classes. Just look at the United States Oil Fund LP (ETF) (NYSE: USO), which is higher by more than 12 percent. That bullishness is having a positive effect on energy equities. The Energy Select Sector SPDR (ETF) (NYSE: XLE) is up 13 percent over the past 90 days.

Some of that ebullience is trickling down to exchange-traded funds tracking master limited partnerships (MLPs), though not in significant fashion. For example, the Global X Funds (NYSE: MLPA) and the Global X MLP & Energy Infrastructure ETF (NYSE: MLPX) are each up just over 3 percent over the past three months.

Focus On MLPX

MLPX one of the MLP ETFs that features general partner exposure. In an environment where MLPs are in favor, which was seen prior to oil's precipitous decline starting in 2014, general partners can shine. General partners have several advantages, including less tax complexity than MLPs and more dividend flexibility.

“MLPX invests in midstream infrastructure entities such as pipelines and storage facilities that have less sensitivity to energy prices,” according to Global X.

The ETF holds 37 stocks and is home to more than $132 million in assets under management.

MLPA In Focus

The aforementioned MLPA also invests in midstream pipelines and storage facilities. That $377.1 million ETF holds 22 stocks and its top 10 holdings combine for nearly two-thirds of its weight.