Google and Mastercard cut a secret ad deal to track retail sales — Bloomberg — “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… Google paid Mastercard millions of dollars for the data, according to two people who worked on the deal.”