10. UBS E-TRACS Nat Gas Ft Contango ETN ( GASZ) began trading on Jun. 15, 2011. The fund seeks to link the daily perfromance of the ISE Natural Gas Futures Spread Index. The fund tracks continuous exposure to the natural gas futures prices in the form of a multi-position horizontal spread. The spread position is established such it provides a 1 long to 1 short notional based exposure. Just like OILZ, as the spread increases so do potential gains.