's (NASDAQ:AMZN) showrooming effect may finally be catching up to the country's leading discount department-store chains.

Shares of Target (NYSE:TGT) fell on Wednesday after the company posted disappointing quarterly results and lowered its earnings guidance for the entire fiscal year. Wal-Mart (NYSE:WMT) slipped last week after a rare miss on the bottom line. However, both companies are also falling short on the top line, as Target and Wal-Mart posted surprisingly negative same-store sales for the current quarter.

Amazon hasn't had a problem growing its sales, so is showrooming -- when folks turn to online retailers for better deals -- finally starting to hurt the discounters? Wal-Mart and Target sell a lot of perishables and other non-discretionary goods for which Amazon isn't an alternative, but it's hard to ignore the soft comps. Wal-Mart and Target blame the late winter season and the late start to the distribution of tax refunds in some cases, but why isn't Amazon smarting?

In this video, longtime Fool contributor Rick Munarriz explores the possibility that Amazon is finally eating into the discounters.

Longtime Fool contributor Rick Munarriz has no position in any stocks mentioned. The Motley Fool recommends and owns shares of Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.