ETFs tracking gasoline prices flared up Friday as futures surged 3.5% on tight supplies in the storm-ravaged Northeast and expectations of the region's slow recovery boosting demand. But analysts believe the spike is just a knee-jerk reaction to Superstorm Sandy as ample U.S. supplies have led to lower pump prices in the past month. United States Gasoline (UGA) -- the largest ETF tracking gasoline futures -- soared 3.8% to 56.53. It ended the week