After reporting its fiscal Q1 2023 earnings Wednesday, Target shares tumbled 26% in just the first 15 minutes of trading -- just one day after a smaller earnings miss sent its much larger rival, Walmart (NYSE: WMT), spinning into a near-12% loss. On "Black Monday" -- October 19, 1987 -- shares of retail giant Target (NYSE: TGT) suffered their steepest one-day decline ever, falling 32.8% in a single day . Walmart blamed its dip into red ink on its purchases of inventory -- at prices heightened by inflation -- presumably to stock up against supply chain snarls.