Google secretly tracking users offline purchase data with Mastercard: Previously Google admits, they track users even after they turn off location tracking and now this. Google has a secret deal with Mastercard that allows it to track the user’s offline purchase data so, they can link it with adverts.

Over the past year, the multi-million dollar deal has given the tech titan unprecedented insight into whether the ads it runs online translate into real-world purchases.

Users are able to opt out of being tracked. However, the deal, uncovered by this week by Bloomberg, was not disclosed to the public by either Google or Mastercard.

Google has boasted that this new feature for advertisers, called Store Sales Measurement, gives the company access to about 70% of U.S. credit and debit card data.

The company hasn’t named who its partners are, but it’s likely more than just Mastercard. It’s currently being tested with a small group of advertisers, reports Bloomberg. Google adds that users can opt out of this kind of tracking via its “Web and App Activity” setting.

You can read the full Bloomberg report here.