Winter is already blowing cold for retailers. Just this week, J.C. Penney (OTC:JCPN.Q) reported a 26% decline in same-store sales as Kohl's (NYSE:KSS) warned that steep discounting could take a big bite out of Q4 results. Yet neither fared so poorly as Groupon (NASDAQ:GRPN), which fell 29% after reporting a meager 3% gain in European sales during the third quarter. Troubling? Sure, but declining cash flow is far more worrisome. Find out why in the following video.

 
 
 
This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.