The Nasdaq Biotech index is down 0.9 percent, falling for a seventh session out of the past nine.
Biotechs are a frequent target for profit-taking, as many investors view the group which largely trades on future growth prospects and such volatile elements as drug pipeline progress as overvalued.
Vertex Pharmaceuticals lost 1.2 percent to $93.10 while Amgen was off 0.9 percent to $137.64 and Regeneron Pharma lost 1 percent to $346.82.
Amarin Corp fell 20 percent on the Nasdaq, dropping to $1.44 after the company said the Food and Drug Administration had rejected a preset testing process for the second time.
The stock was the biggest decliner in the Nasdaq Biotech index and was suffering its biggest one-day decline since Jan. 21. It is down almost 30 percent year-to-date.