Even though the U.S. Natural Gas Fund (NYSEArca: UNG) and the iPath S&P 500 VIX Short Term Futures ETN (NYSEArca: VXX) have each lost more than 90 percent of their value since inception, investors continue to pour in assets, according to an article on ETF Trends.

Despite their poor track records, UNG holds around $1.1 billion in assets, while VXX carries about $1.7 billion. Out of the two, VXX has caused the most damage to investors. The fund shed close to 96 percent since it launched on Jan. 29, 2009, and has lost more than 57 percent so far this year, the article said.

One thing VXX and UNG share is that both funds track futures contracts and fall victim to contango.

Contango is the condition in futures markets when front-month contracts are less expensive than contracts that expire in the future. It destroys investment returns because when fund managers “roll” exposure ahead of a given contract’s expiration, they fetch less selling the expiring contract than they have to pay for the new contract.

Not only is VXX fastened to futures, the futures are of contracts tied to the CBOE Volatility Index, which makes this fund even more of a gamble, reports ETF Trends.

Head over to ETFtrends.com for the full story.