** Shares of digital ad verification firm Integral Ad Science IAS.O rise more than 20% to $10.2 premarket
** Private equity firm Novacap to buy co, valuing IAS at about $1.9 billion
** Novacap to buy all outstanding shares of IAS for $10.30 per share in cash, a 22% premium on stock's last close
** Deal expected to close before end of 2025
** As of last close, shares down ~19% YTD