Google and Mastercard Cut a Secret Ad Deal to Track Retail Sales 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 U.S.  That insight came thanks in part to a stockpile of Mastercard transactions that Google paid for. Source: https://www.bloomberg.com/news/articles/2018-08-30/google-and-mastercard-cut-a-secret-ad-deal-to-track-retail-sales