Retail spending was up 3.9% in October, which should be a good sign for retailers heading into the holiday season. But Wal-Mart (NYSE:WMT), Target (NYSE:TGT), and Best Buy (NYSE:BBY) are either growing more slowly than the overall market or even seeing store sales decline. 

The reason for the brick-and-mortar weakness may be none other than Amazon.com (NASDAQ:AMZN), which will soon pass Target in sales. Every percentage point of growth Amazon gains has to come from somewhere, and it looks like it's coming from Wal-Mart, Target, and Amazon. 

Erin Miller sat down with the Fool's Travis Hoium to see how investors should react.