One of the most interesting success stories in the ETF industry is that of the United States Natural Gas Fund (UNG). After a moderately successful first 18 months that saw assets climb above $700 million, interest in natural gas as an investment surged in 2009 amidst big drops in prices, political pushes to reduce dependence [...] Related Stories: Guide To Volatility ETFs: Volatility ETN Investing 101 Volatility ETFs Continue Freefall: Time To Buy? VIX Drops to Lowest Level Since 2008: Time For A VIX ETF?