The Federal Trade Commission under President Trump joined 22 states in suing Amazon on Monday over alleged undisclosed increases to the lowest prices advertisers paid for ads. The Wall Street Journal said the complaint claims the practice began in 2018, covered search ads on the site and app in several sponsored formats, cost advertisers more than $20 billion, and raised prices for shoppers.

Amazon auctions were meant to charge the winner just above the second-highest bid, yet the agency says the company later raised some winning prices after auctions ended and used the method in 70 to 80 percent of recent auctions, with extra charges at Christmas and other peak times. Amazon operates the third-largest digital ad platform after Google and Meta, called the case misguided, and said the agency misunderstands how advertisers work. Chairman Andrew Ferguson said the practice affected food and groceries ordinary Americans buy, and a former FTC litigation official said it raised rivals costs while adding to Amazon profits.