Walmart Backing Away From Trade Desk, an Amazon Ad Tech Rival

Amazon’s most direct rival in handling ad sales across the web, the Trade Desk, could be in danger of losing one of its most valuable clients—Walmart.

Last year, Walmart renegotiated its four-year-old arrangement with the Trade Desk, under which advertisers buying spots on the Web using Walmart shopper data for targeting have to use the Trade Desk’s technology. The new arrangement is no longer exclusive, according to a person with knowledge of the situation, which means the retail giant can tap the ad-buying platforms of other ad tech firms.