These Are the Fortune 500’s Fastest-Growing Companies by Jen Wieczner @FortuneMagazine June 28, 2016, 1:01 PM EDT E-mail Tweet Facebook Linkedin Share icons After a record-setting year of mergers and acquisitions, it shouldn’t be much of a surprise that the Fortune 500 companies that grew revenue most in 2015 did so through M&A. Indeed, companies have been struggling to grow their sales for the last several years, opting instead to strike transformative deals that have in some cases doubled their size overnight. All five of this year’s fastest-growing Fortune 500 companies took part in a major merger or acquisition in 2015 (or several) that accounted for their double- or even triple-digit revenue growth. Without such deals, one of those companies, trucking concern XPO Logistics, wouldn’t have made the Fortune 500 list at all. (Mergers and acquisitions were also a big theme among the Fortune 500’s fastest-growing companies last year, but not for all of them.) The M&A wave has slowed in 2016, thanks in part to a string of deal-busting decisions by U.S. antitrust regulators. It remains to be seen whether the fastest-rising companies will be able to achieve the same blockbuster growth as this year’s top companies if they aren’t able to complete as many mergers. Below are the five Fortune 500 companies that grew revenue the most in 2015. Visit our new Fortune 500 list for more information and breaking news about all of America’s largest companies.