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

Cognex Corporation (symbol: CGNX) was one of the worst losers of the
trading day today (2015-08-04), losing -22.14%. The number of shares that
changed hands was 5,374,409, or about 7 times the average daily volume in
the stock.
The closing price was $35.0, amounting to a market cap of $3,050,000,000,
about -33.31% off the highest price in the last 12 months. The stock has
been trading at a range between $32.35 and $52.48.
CGNX is in the Industrial Machinery/Components industry, part of the
Capital Goods sector. It first went public in 1989.
Looking at its valuation, the stock is now trading at 25.34 times earnings.