Marquee Nasdaq names like Google(GOOG), Amazon.com(AMZN), Yahoo(YHOO) all finished down more than 4%. Facebook(FB) fell over 5% after gaining Wednesday. Part of this is likely due to a correction in momentum stocks, but concerns about the Heartbleed bug are also playing a role.
The biotech sector was part of the Nasdaq bleed as well. Biogen Idec(BIIB), Celgene(CELG), and Vertex(VRTX) all fell between 4% and 6%. Gilead Sciences(GILD) plunged more than 7%.