While the pharmaceutical space has been generating hefty returns for investors since the start of the year, shares of Teva Pharmaceuticals (TEVA 3.01%) are up a mere 2.7%. Compare that with Dow component Pfizer, which has soared almost 14%, and generic-drug maker Mylan, up 42% since the start of 2013, and it's clear that something serious is muting Teva's growth. In the following video from The Motley Fool's health-care show Market Checkup, analysts David Williamson and Max Macaluso discuss the major competitive threats confronting Teva today.