Both the First Trust Dow Jones Internet Index (FDN) and SPDR S&P Biotech (XBI) exchange-traded funds led markets higher Wednesday, fueled by the better-than-expected earnings season and improving outlooks.
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Last month, Yellen signaled during her testimony on policy that interest rates will likely remain low and monetary policy will remain "accommodative," but she identified social media and some biotech stocks as looking "frothy." Yellen warned that investors may be reaching for yield and perhaps taking on too much risk.
These comments sparked a selloff in both sectors and contributed to the decline in U.S. equities over the past month. But recently the ETFs representing social media and biotech surged higher as impressive quarterly results have strengthened the fundamental outlook of each sector.