$RGEN is one of biggest losers #stocks today. read more:

Repligen Corporation (symbol: RGEN) was one of the worst losers of the
trading day today (2015-09-29), losing -11.76%. The number of shares that
changed hands was 805,096, or about 3 times the average daily volume in the
stock.
The closing price was $27.9, amounting to a market cap of $918,190,000,
about -34.32% off the highest price in the last 12 months. The stock has
been trading at a range between $19.02 and $42.48.
RGEN is in the Biotechnology: Biological Products (No Diagnostic
Substances) industry, part of the Health Care sector. It first went public
in 1986.
Looking at its valuation, the stock is now trading at 125.68 times earnings.