Exchange-traded funds that track the biotechnology sector jumped on Friday, supported by a huge gain in industry bellwether Biogen, which climbed after a positive drug trial. The iShares Nasdaq Biotechnology ETF jumped 2.7%, on track for its biggest one-day percentage gain since May 11. The SPDR S&P Biotech ETF was up 1.9%. Biogen is a major component of both funds, and it climbed 15.5%, its biggest one-day gain since 2007. The rally came after it announced positive results from a phase 2 trial for an Alzheimer's treatment. The Dow Jones Industrial Average rose 0.2% while the S&P 500 was up 0.4%. The Nasdaq Composite Index popped 0.7%.