(Reuters) -Private equity firm Novacap will buy Integral Ad Science in a deal valuing the target at around $1.9 billion, the digital ad verification company said on Wednesday. Novacap, having more than $10 billion in assets under management, will acquire all of IAS' outstanding shares for $10.30 apiece in cash, representing a premium of around 22% to the stock's last closing. IAS shares were trading about 20% higher before the bell. The deal, expected to close before the end of this year, is the latest i ...