Neither company has publicly announced the business partnership, which gave Google an invaluable tool for measuring retail spending, Bloomberg reported. Google paid Mastercard millions of dollars for the data, the news outlet reported, citing unidentified people with knowledge of the deal.
The revelation comes amid heightened concern about how much consumer data is consumed by tech companies like Google. Earlier this year, Facebook was criticized when data on as many as 87 million people was, raising questions about Facebook's handling of user data and whether the company is doing enough to protect it.
A Google representative declined to comment on the alleged partnership with Mastercard, focusing instead on the ads tool it launched last year.
"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," Google said in a statement. "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."
Google said people can opt out of the program using Google's "Web and App Activity" controls.
In announcing its new Store Sales Measurement program last year, Google said third-party partnerships allowed it to capture 70 percent of all payment card transactions in the US. Google can match in-store spending to ads if a consumer provides their email address at the register. For consumers who don't provide an email address, Google relies on third-party providers of payment-card transaction data.
Bloomberg reported that the process begins when a consumer logged into a Google account clicks on an ad for an item they're browsing the web for but doesn't purchase at that time. If that consumer then uses their Mastercard to purchase the item at a physical store with 30 days, the sale is reported to the advertiser who ran the ad. The advertiser gets a report that lists the transaction in a column labeled "Offline Revenue," Bloomberg reported.
Other tech giants have been under fire for scandals related to data privacy, and the issue has caused some concern in Congress. The House Committee on Energy and Commerce last month to Apple and Alphabet, Google's parent company, inquiring how the companies protect users' privacy. with detailed answers to each question; Alphabet hasn't.
Earlier this month, the Associated Press reported that Google services on Android devices and track and store your location data even if you turn location history off in your privacy settings. Google reportedly uses this location data to target ads based on users' specific locations.
Mastercard did not immediately respond to a request for comment.
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