Imperva Shares Plunge Below $40 Amid Sale Concerns By: Benzinga via Benzinga October 19, 2016 at 09:20 AM EDT Shares of Imperva Inc (NYSE: IMPV) tanked more than 15 percent in the pre-market trading on Wednesday after concerns were raised on the ... Read More >> Related Stocks: Bio-Techne Corp Cisco Systems International Business Machines