Google and Mastercard reportedly struck a secret deal, that allows Mastercard to share credit card data with Google. The reason for this is for Google to help advertisers figure out how many sales actually came from the ads they have run on Google. While Google can already show them conversion rates - how many clicked on the ad, versus how many saw the ad - this credit card data deal allows the advertisers to get even more information.
This partnership is probably not surprising to many people, and Mastercard is not sharing people's personal information, just their purchases. But the fact that this deal was never publicly announced, is going to raise some red flags on privacy concerns. Google already collects so much data from everyone on the internet and now it's getting your purchases - both online and in retail stores - that it can share with its Adwords users. This deal, apparently, had been in the works for nearly four years before it ultimately was set up last year - around the time that Adwords start sharing purchasing habits with advertisers. Part of the reason for Google going after Mastercard for this deal was to compete with companies like Amazon.
Alphabet and Google both refused to comment on the matter, when Bloomberg reach out regarding this. But Mastercard's spokesman, Seth Eisen did comment saying that Mastercard does share transaction trends with merchants and their service providers so they can better measure "the effectiveness of their advertising campaigns." Eisen did not speak about Google, but rather generally about Mastercards sharing data. The information that Mastercard shares includes sales volumes and average size of the purchase. But that information is only shared with the permission of the merchant, not permission of the cardholder. Eisen did emphasize that no personal data or individual transaction data is released.