Shares of Electronics for Imaging Inc. soared 26% toward an 18-month high in premarket trade Monday, after the digital imaging company announced a deal to be acquired in a cash deal valued at $1.7 billion by private equity firm Siris Capital Group LLC. Under terms of the deal, Siris will pay $37 for each Electronics for Imaging shares outstanding, which is 26% above Friday's closing price of $29.40. Electronics for Imaging said there will be a "go-shop" period over the next 45 calendar days.