A new report from Bloomberg News revealed a deal between Google and Mastercard that allowed the Silicon Valley giant to track certain retail purchases.

A secret deal between Google and Mastercard allows Google to track certain retail purchases, according to a report from Bloomberg News. The arrangement gives Google access to all Mastercard purchases that were made in physical retail stores after a user had clicked on a Google ad for a similar product online.

Here’s how Bloomberg describes the tracking process:

It works like this: a person searches for “red lipstick” on Google, clicks on an ad, surfs the web but doesn’t buy anything. Later, she walks into a store and buys red lipstick with her Mastercard. The advertiser who ran the ad is fed a report from Google, listing the sale along with other transactions in a column that reads “Offline Revenue” — only if the web surfer is logged into a Google account online and made the purchase within 30 days of clicking the ad. The advertisers are given a bulk report with the percentage of shoppers who clicked or viewed an ad then made a relevant purchase. Mastercard’s spokesman said the company does not view data on the individual items purchased inside stores.

The deal is causing concern amongst privacy analysts who argue that this is just the latest in a series of oversteps by big data companies like Google.

Christine Bannan, counsel with the advocacy group Electronic Privacy Information Center (EPIC), said that the deal is especially worrisome because consumers were not notified that this information would be collected. “People don’t expect what they buy physically in a store to be linked to what they are buying online,” Bannan said. “There’s just far too much burden that companies place on consumers and not enough responsibility being taken by companies to inform users what they’re doing and what rights they have.”

Despite the increasing invasions on user privacy, Google’s advertisement business took in $95.4 billion in 2017 and has continued to grow at a whopping 20 percent each year, according to the report.

Google is not the only Silicon Valley Master of the Universe seeking details of consumers’ financial lives. Facebook has reportedly been seeking agreements with major banks to share customer information so that it can offer financial products to users while they are on social media.

Mastercard has been at the center of several high profile cases recently of financially blacklisting conservatives including Robert Spencer’s Jihad Watch and the David Horowitz Freedom Center. Mastercard and payment processor Worldpay eventually backed down in the case of the Freedom Center after coverage by Breitbart News and the Drudge Report.