For investors looking to obtain significant exposure to the uranium market within the metals and mining sector, the choices among exchange-traded funds (ETFs) are simplified. As of June 2016, there are only two ETFs with a primary focus on the uranium market. One ETF is a more pure-play investment in uranium itself or uranium mining, since its portfolio is dominated by uranium producers. The other ETF choice in this category offers a more direct play on nuclear energy firms, though stocks of major uranium producers are also represented in the fund's portfolio.

These two ETFs are similar in that both have a relatively short list of portfolio holdings, at about 25, but one ETF dwarfs the other in terms of total assets under management (AUM).

Global X Uranium ETF

The Global X Uranium ETF (NYSEARCA: URA) was launched by Global X Funds in 2010 and commands the lion's share of assets invested in uranium ETFs, with $116.5 million in AUM, as of June 2016. This ETF tracks the market cap-weighted Solactive Global Uranium Index, which is composed of the largest and most widely traded companies engaged in the business of uranium mining and refining, including mining equipment companies. The majority of stocks that make up the index are equities of small-cap or micro-cap firms.

The fund is typically 80% or more invested in the stocks contained in the underlying index, or in American depositary receipts (ADRs) or global depositary receipts (GDRs) that represent index securities. The portfolio is concentrated at the top, with the top three of 24 total holdings accounting for 48% of the portfolio's assets. The top three holdings are Cameco Corp. (NYSE: CCJ), which alone accounts for 22% of the portfolio, NexGen Energy Ltd. (OTC: NXGEF) and the Uranium Participation Corp. (OTC: URPTF). Cameco holds a central position as the world's largest publicly traded uranium mining firm, producing about 18% of the world's uranium. The annual portfolio turnover ratio is a relatively moderate 22%.

The expense ratio for the Global X Uranium ETF is 0.70%, well below the natural resources category average of 1.02%. The fund has a 12-month dividend yield of 1.96%. The five-year average annualized return for this ETF is a disappointing negative 26.47%. The one-year return is negative 20.45%. However, the fund was up 2.14% year to date (YTD), as of June 2016.

This ETF is appropriate for investors seeking overall coverage of the uranium mining industry.

VanEck Vectors Uranium+Nuclear Energy ETF

VanEck launched the VanEck Vectors Uranium+Nuclear Energy ETF (NYSEARCA: NLR) in 2007, but despite having a three-year head start on URA, this ETF only has about a third of URA's asset total, with $38.6 million in assets under management. Although its asset base is large enough to make fund closure an unlikely possibility, the average bid-ask spread of 0.74% is notably wider than URA's 0.41%. However, for investors seeking a blend of nuclear energy and uranium mining stocks, NLR is the best available choice in the ETF market.

The VanEck ETF tracks the market cap-weighted MVIS Global Uranium & Nuclear Energy Index, which is designed to reflect the overall market performance of companies in the nuclear energy and uranium mining industries. The fund portfolio includes both index securities and depositary receipts. The portfolio of 29 stocks has less concentration at the top than URA, with the three largest holdings only making up 23% of the total portfolio. The top three holdings are Duke Energy Corp. (NYSE: DUK), the Southern Company (NYSE: SO) and Dominion Energy Inc. (NYSE: D). Unlike URA, this ETF is heavily populated with large-cap firms and tilted toward U.S. and Japanese companies, to the neglect of major nuclear energy firms in France and Canada. The portfolio turnover ratio is 27%.

The fund's expense ratio is 0.61%, above the miscellaneous sector category average of 0.45%, but below URA's 0.70%. NLR also has a higher 12-month dividend yield than URA, at 3.07%. The five-year average annualized return is negative 0.62%. The one-year return is 8.58%, and as of June 2016, the fund was up 11.77% YTD.

From purely a performance and expense viewpoint, NLR has obviously been the better choice for investors over the time frame from mid-2011 to mid-2016.