Adblock, the popular extension for Chrome and Safari, has announced via a pop-up to users that it has been sold — but doesn't mention a price or a buyer. The company was previously privately owned by its founder, Michael Gundlach.

The pop-up's main message is to reveal that Adblock is implementing the "Acceptable Ads" policy that runs on Adblock Plus along with a selection of other ad blockers. Eyeo, the company behind AdBlock Plus, told Business Insider that "we’re very happy to welcome AdBlock users to the Acceptable Ads program."

According to The Next Web, the buyer specifically requested that they remain anonymous, and sources tell us that it was not Eyeo, the most obvious candidate.

Adblock reportedly has over 40 million users, and the deal comes at a time when intense scrutiny is being placed on "content blockers" in general. The latest version of iOS includes the ability to install an app that then strips adverts out of webpages, potentially endangering the revenue model of publishers and other businesses.