Shares of Gap Inc. (NYSE: GPS) soared 15.2% on Friday -- and 18% for all of last week -- after announcing encouraging financial results for the five weeks ending Oct. 1. The numbers don't sound impressive at first glance. Net sales for the month clocked in at $1.43 billion, 2% below last year's comparable five-week period. Comps fell 3% across all of its brands, and that's pitted against a 1% dip a year earlier. In other words, the average store is ringing up 4% less in sales than it did two years earlier.