IBB is off its highs of the day, but is trading slightly higher after earlier touching another all-time high. The same can be said of the Market Vectors Biotech ETF (NYSEArca: BBH), which is up 0.4% at this writing, extending its year-to-date gain to 20%. The $798 million BBH has a 7.9% weight to Biogen, making the stock the ETF’s fourth-largest holding.

Gilead Sciences, the maker of the well-known hepatitis-C treatments harvoni and sovaldi, is also providing some help to biotech ETFs Friday. RBC said harvoni prescriptions rose 2% last week while combined harvoni and sovaldi prescriptions also increased 2%, which would put first-quarter Harvoni sales at $3.2 billion, above Wall Street estimates of $2.8 billion to $2.9 billion, according to Barron’s.

Gilead is BBH’s largest holding at a weight of 12% and the stock is almost 7% of IBB’s lineup.

Market Vectors Biotech ETF