According to the ETF Finder at ETF Channel, ALNY makes up 2.24% of the SPDR S&P Biotech ETF (XBI) which is lower by about 0.2% on the day Friday.
In afternoon trading Friday, ALNY was down about 0.2% on the day.
It was the seventh best performer in the index during the first half of the year.
Also on the move were Global Blood Therapeutics, Valeant and Kite Pharma, among others.
Here's how to bank some gains.