As the second-best performing sector in the S&P 500 this year, the energy group has made winners of plenty of exchange traded funds.

The Energy Select Sector SPDR (NYSEArca: XLE), the largest equity-based energy ETF by assets, has attracted nearly $3.2 billion in new assets this year, more than any other sector ETF. In just the second quarter, XLE has pulled in almost $2.3 billion in new assets. [Energy ETFs Dominate Sector Flows]

More important than the superlatives of inflows are the returns offered by an array of energy funds. Of the top-25 non-leveraged ETFs over the past three months, 13 are either equity-based energy funds or ETFs focusing on master limited partnerships. [Soaring Demand for Energy ETFs]

Often times in scenarios like this, a couple of ETFs end up flying under the radar. Such is life for the iShares MSCI Global Energy Producers ETF (NYSEArca: FILL). FILL, which is tiny with just $5.7 million in assets under management, is up 12% this year.

FILL debuted in early 2012 as part of a five-ETF suite of specialized, equity-based commodities funds. The ETF tracks the MSCI ACWI Select Energy Producers Investable Market Index, giving it exposure to nearly 230 global energy producers, including a 49.5% weight to the U.S.

FILL can either be viewed as a competitor or an alternative to the iShares Global Energy ETF (NYSEArca: IXC) and, to a lesser extent, the SPDR S&P International Energy Sector ETF (NYSEArca: IPW) though IPW has no exposure to U.S. companies.