Leveraged ETF Winners, September 12th 2012: Velocity Shares 3x Long Natural Gas ETN (NYSEARCA:UGAZ): +6.42% ProShares UltraPro Short 20+ Year Treasury ETF (NYSEARCA:TTT): +3.63% Direxion Small Cap Bull 3X Shares ETF (NYSEARCA:TNA): +2.02% Leveraged E...