For years, American shoppers flocked to stores on Black Friday — the day after Thanksgiving when deals were as abundant as drivers clogging roadways to get to their favorite stores.
Then came Cyber Monday, the Monday after Black Friday when online deals dominated the shopping universe. On July 15, 2015, Amazon changed the equation again with its first-ever Prime Day. Walmart (NYSE: WMT) and Target (NYSE: TGT) soon followed with special online sales days.
This year, the three retail giants added...