Wal-Mart (NYSE:WMT) has been a dominant player in retail for decades, but there may be some chinks in its armor. Over the past five years, growth has underperformed direct rivals Target (NYSE:TGT) and Costco (NASDAQ:COST), while it's been crushed by Amazon.com (NASDAQ:AMZN)

Demographic shifts as well as self-inflicted wounds from too little inventory and uninspiring store design have Wal-Mart following instead of leading in retail, an uncomfortable position for the company. The Fool's Erin Miller recently sat down with analyst Travis Hoium to see what trends investors should be watching.