It seems that Alphabet and Mastercard have hooked up: Mastercard seems to have agreed to share its customers’ shopping habits with Alphabet’s Google in return for Google’s separately accumulated data on those same customers.  The subhead on Bloomberg‘s piece is instructive:

Google found the perfect way to link online ads to store purchases: credit card data

The hookup is this:

For the past year, select Google advertisers have had access to a potent new tool to track whether the ads they ran online led to a sale at a physical store in the US. That insight came thanks in part to a stockpile of Mastercard transactions that Google paid for.

And that Mastercard freely sold.

Who knew the deal had been done?  Almost nobody, especially including the owners (morally if not legally) of those data.

[M]ost of the two billion Mastercard holders aren’t aware of this behind-the-scenes tracking. That’s because the companies never told the public about the arrangement.

Then this:

[T]he deal, which has not been previously reported, could raise broader privacy concerns about how much consumer data technology companies like Google quietly absorb.

Gee.  Ya think?

It also raises the broader privacy concern of how much personal that data primary collectors, like credit card companies, are busily peddling to the Googles of the world behind our backs.

A carefully anonymous Google spokeswoman offered this:

Before we launched this beta product last year, we built a new, double-blind encryption technology that prevents both Google and our partners from viewing our respective users’ personally identifiable information.  We do not have access to any personal information from our partners’ credit and debit cards, nor do we share any personal information with our partners.

Trust us.  Trust us both.

Sure.