In a quick text, billionaire finance executive Bill Ackman last year pushed credit card companies to stop working with Pornhub—and that plea ultimately led to the adult website dumping millions of unauthorized videos, according to a new report. Bill Ackman, the CEO of the hedge fund company Pershing Square Capital Management, told Institutional Investor that a December New York Times report alleging millions of videos of child porn on Pornhub sprung him into action. After calls to leaders of human trafficking groups, Ackman sent a text to a friend of his: MasterCard CEO Ajay Banga, letting him know about the report and urging the company to remove its cards from the site. “We’re on it,” Banga replied in a text message. Within days, MasterCard removed its cards from the platform, with Visa following shortly after. It was less than 24 hours before Pornhub announced it had taken down 10 million videos on the site.

Ackman said his actions were to promote environmental, social, and governance investing—ESG—which is meant to incorporate ethical standards when investing in companies. He said in a tweet at the time he saw his four daughters in the story of Pornhub, prompting him to make a difference.