NEW YORK ( TheStreet) -- The new natural gas ETF from Jefferies ( JEF) should not be the cornerstone of your energy holdings. Launched Wednesday, the Wildcatters Exploration & Production Equity ETF ( WCAT) offers exposure to small- and mid-cap firms in the oil and natural gas sectors. While exposure to these firms may be helpful in balancing your energy holdings, WCAT will be more volatile than established funds like the First Trust ISE-Revere Natural Gas Index Fund ( FCG), which tracks larger-cap names. WCAT joins other popular funds like United States Natural Gas ( UNG) and FCG in offering exposure to the natural gas sector with a small-cap twist. WCAT has an expense ratio of 0.65% and 55 underlying holdings. The top three holdings in WCAT's underlying portfolio -- Forest Oil ( FST), Encore Acquisition ( EAC) and St. Mary Land & Exploration ( SM) -- make up 5.77%, 5.09% and 4.69% of the fund respectively. Buying into a portfolio of small-cap companies can be a volatile proposition, but WCAT's methodology helps to mitigate the risk of trying to pick single natural gas stocks. A wave of small-cap ETFs like WCAT have helped to round out an ETF universe still dominated by market-cap weighted funds. Equity funds like WCAT and FCG also help to provide exposure to natural gas prices without relying on the purchase of natural gas contracts. UNG, which is designed to track a basket of NYMEX-traded futures, has been the target of commodities reform in recent months. Quartered in both the United States and Canada, WCAT's holdings offer a higher-beta play on the natural gas and oil sectors. While investment in these small-cap stocks may be risky, they also offer the potential for merger and acquisition activity and higher growth.