Shares of Karuna Therapeutics Inc. KRTX, +1.80% rocketed 47.3% into record territory in premarket trading Friday, after the biopharmaceutical company announced an agreement to be bought by Bristol Myers Squibb Co. BMY, +0.59% in a deal valued at $14 billion. Bristol Myers’ stock slumped 2.2$330 in cash for each Karuna share outstanding, which represents a 53.4% premium to Thursday’s closing price of $215.19. The agreement was reported ear ...