Buysiders don't expect Fed Chairperson Janet Yellen's bearish biotech comments to trigger a long-term downturn in the sector. Nevertheless, her remarks about inflated valuations in biotech and social media did send the biotech indices downward last week.

In remarks before Congress on the Fed's semiannual monetary policy report on Tuesday, Yellen said, "Valuation metrics in some sectors do appear substantially stretched - particularly those for smaller firms in the social media and biotechnology industries, despite a notable downturn in equity prices for such firms