With Sandy disrupting 25% of the population for roughly three-quarters of a percent of the year, its maximum impact shouldn’t exceed $30 billion. But it’s probably less due to heavy telecommuting, Netflix and Amazon! Had Sandy hit an oil refinery or power plant, costs would have skyrocketed. On the plus side, rebuilding what was destroyed will boost GDP in future quarters. Katrina was the most devastating hurricane, costing $108 billion.