Biotech stocks have been on a tear this week.
The SPDR S&P Biotech (XBI) exchange-traded fund climbed 4.7 percent on Wednesday, putting it on track to post its best weekly performance since March 13. The biotech ETF has already outperformed the broader market year to date, rising 30 percent in the period. The S&P 500 has gained about 9 percent in 2017.
The rise in biotech helped the broader S&P health care sector rise about 1 percent on Wednesday.