Health insurer Cigna ranked 65th on the Fortune 500 last year. This year? A meteoric rise to 13th, the result of its merger with pharmacy benefits giant Express Scripts—and another instance of the trend toward vertical integration among large health care companies. The Express Scripts integration, completed in December 2018, fueled revenue growth that exceeded even Cigna’s own pre-merger expectations: Adjusted revenues for 2019 soared to $140 billion, compared with the $131 to $133 billion originally forecast.