While Arena Pharmaceuticals (NASDAQ:ARNA) and VIVUS (NASDAQ:VVUS), makers of the obesity drugs Belviq and Qsymia, respectively, both garner a lot of attention on Fool.com, they also have attracted the attention of the short sellers. In this video, Motley Fool health-care analyst David Williamson talks about the "buy the run-up, short the launch" trend, and whether the short-sellers are right not to believe in these stocks.

David Williamson owns shares of Amarin. Follow him on Twitter, @MotleyDavidMax Macaluso has no positions in the stocks mentioned above. The Motley Fool owns shares of Dendreon. 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.