Amazon.com Inc is taking its most assertive step yet into the digital-
Amazon.com Inc is taking its most assertive step yet into the digital-advertising market by testing a new display ad offering that threatens multibillion-dollar revenue streams at Google and firms like Criteo SA. The tool lets merchants selling on Amazon’s online marketplace purchase spots that will follow shoppers around the web to lure the consumers back to Amazon to buy. The company is inviting select merchants to test the new ads later this month, according to people with knowledge of the plans. Currently, merchants can buy other types of ads on Amazon, and the company has been giving more-prominent placement to these sponsored product spots in its search results. The new tool lets these sellers bid on ads that will appear on other websites and apps, giving them much wider reach. Merchants will only pay Amazon when customers click on the ads. Amazon said it can help merchants target shoppers who have viewed their products or similar ones, according to an invitation to try the new ...