The iShares Nasdaq Biotechnology ETF, which has 1% allocated to HALO, declined 4.2% Friday. Additionally, the SPDR S&P Biotech ETF (NYSEArca: XBI), which follows a more equal weight approach and leans toward riskier mid- and small-cap stocks, such as a 1.2% weight in HALO, plunged 5.4% Friday and is now testing its 200-day simple moving average.

iShares Nasdaq Biotechnology ETF

For more information on the biotech sector, visit our biotechnology category.

Max Chen contributed to this article.