Blue Nile Inc. announced Monday a deal to be acquired by private-equity firm Bain Capital Private Equity for $500 million. Under terms of the deal, Blue Nile shareholders would receive $40.75 in cash for each share they own, a 34% premium to Friday's closing price, and a level not seen since February 2014. The deal, which is expected to close in the first quarter of 2017, may solicit other buyout proposals during a 30-day go-shop period. "Since its inception, Blue Nile's guiding principle has been to provide value to its customers, suppliers, and shareholders, and this transaction provides tremendous...