The biotech sector has been hit hard in 2014, with many of the biggest names in the industry taking falls. Three top companies, Alnylam Pharmaceuticals (ALNY 1.05%), Theravance (NASDAQ: THRX), and Amgen (AMGN -0.04%), are all down year to date. But are these tumbling biotech stocks great opportunities for investors in search of rebound candidates in 2014?

Alnylam has made progress on its RNA interference program, and the company has reported upbeat clinical data lately. Theravance has increasingly pushed into the growing COPD market in recent years. Amgen, one of the largest biotechs on the market, took an earnings-related hit in April, but there could be an opportunity for savvy investors at its valuation.

So why is the market down on these stocks? Find out in the video below, as Motley Fool contributor Dan Carroll takes you through what's behind these three slipping picks and whether they can mount comebacks over the next few months.