Dive Brief:

• Google and Mastercard have an ongoing partnership that gives the internet giant access to credit card usage data from 2 billion Mastercard holders to help it track purchases in physical stores that may have resulted from it online ads, according to a Bloomberg report.

• Google declined comment to Bloomberg about the partnership, but told the publication that its ad-tracking technology — a Store Sales Measurement capability in AdWords — incorporates encryption techniques that keep Google and its partners from seeing one another's user data. Mastercard told Bloomberg that it shares only anonymous data with its merchant partners.

• Google reportedly has been working to bring more location-based and contextual offline shopping conversion data to its ad tools since at least 2014, and last year enhanced the Store Sales Measurement tool with machine learning capability to provide more refined analysis, according to a TechCrunch story at the time.

Dive Insight:

Bloomberg described the partnership as "secret," but it's hard to believe anyone would be surprised by the existence of the partnership or the notion that these two parties could be sharing some types of data on store purchases. Google has been moving in this direction for several years, with the initial availability of the Store Sales Measurement tool and the subsequent enhancements to it are pretty well documented. 

Moreover, Google is not the only one looking to provide clear links between data on in-store activity and online ads. For example, Facebook also has a capability to "track when transactions occur in your physical business location and other offline channels after people see or engage with your Facebook ads," according to the Offline Conversions page of the Facebook Business Advertiser Help Center.

It's not clear what data and data sources Facebook leverages for the capability, but the fact is that such conversion tracking data is becoming increasingly valuable to retailers looking to better understand and serve shoppers.

A more pressing concern, as raised by Bloomberg, is if the parties collecting and sharing the data adequately inform consumers of what's happening, and are giving them the ability to control or opt out of such programs. Google told Bloomberg that consumers can opt out of ad tracking through activity controls that are part of their Google accounts, but it's not clear how many people know about that option or where to find these controls.

Ultimately, to whatever degree Google and Mastercard might be sharing shopping data, both parties made it clear they don't collect or share individual personal details. Also, the main goal of retailers that might look to leverage such data is to provide better service to their customers, in the same way they might use data on website browsing pattern or loyalty program memberships to provide some degree of personalized treatment to their customers.

Given those efforts by retailers, these types of partnerships, whether "secret" or not, are likely becoming a fact of life.