It's always fun watching the best of the best compete in the Winter Olympic games. But, of course, not everyone can win. Plenty of athletes experience the proverbial agony of defeat.

That's the case with investing, too. Not every stock can be a winner. Several health-care stocks proved the point this week. One of the worst performers announced disappointing clinical study results. Two others were slammed in online articles by short-sellers. 

Which health-care stocks emerged as the most horrendous of all? Find out by watching the following slideshow.