Adblock, a popular extension for blocking advertising in Chrome and Safari with more than 40 million users, was quietly sold today.

The extension displayed a popup on October 1 saying that it is now allowing EyeO’s acceptable advertising — which allows advertisers to buy their way onto the whitelist — through the filter.

https://twitter.com/aahaworth/status/649702548358701056

Buried in the bottom of that message, however, was a more notable change: Adblock has been sold.

What’s strange is that the company won’t disclose who it’s been sold to, why it was sold, or how much it was sold for.

For the extension’s claimed 40 million users this raises an interesting question: Can the extension continue to be trusted if the new proprietor is entirely anonymous?

TNW contacted Adblock’s remaining staff to ask if they’d disclose the buyer but the company refused, saying that the purchaser had specifically asked not to be named.

The only thing the team would tell us is that the tool’s creator Michael Gundlach will no longer have any relationship with the company — that probably means he’s cashed out.

Adblock’s previous director, Gabriel Cubbage, is now running things under the new owner.

Since its launch in 2009, Adblock featured a screen that pushed users to pay for the use of the extension because it was classed as “honor-ware.” An ironic gesture, considering its existence technically deprives others of money.

Gundlach worked full time on Adblock after he quit his job in 2011, able to survive on the proceeds of donations from users prompted to ‘gift’ money toward the development when installing the extension.

What’s interesting is six months ago Adblock changed its name suddenly to BetaFish Adblocker, claiming it was an “experiment.”

BetaFish is the name of Gundlach’s holding company that owned Adblock and around the same time had applied for a US trademark on the word ‘Adblock.’

Support staff claimed five months ago that the company was not being purchased by someone or preparing for participation acceptable ad program, but the move may have pre-empted today’s deal.

The name was later changed back to simply ‘Adblock’ without further explanation.

The sale comes at an interesting time for publishers as the debate rages over whether adblocking will become widespread, as Apple has allowed iOS user to block ads on their mobile devices for the first time.

For users of Adblock, the uncertainty over ownership of the Adblock extension is a reasonable concern, particularly if the new buyer has any sort of agenda with the purchase of the extension.

Why would they keep their identity secret, if it’s a legitimate deal? It’s possible that the new owner simply wants to sit back and let the cash roll in, or was looking for a way to gain back some control.

We’ve contacted Michael Gundlach for further comment on the sale and secrecy, but haven’t heard back at time of writing.

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