our complete analysis for Costco Interactive Institutional Research (Powered by Trefis): Global Large Cap | U.S. Costco ( COST ) is scheduled to announce its fiscal second quarter results on Thursday, March 2. In a recent press release, Costco reported that its comparable store sales during January increased by 7%, including the negative impact of gasoline prices and currency effects, largely driven by strong U.S. comparable sales growth of 6%.