2 million advertisers paid more than they realized because Amazon raised the minimum price to place ads without them knowing. It’s the third major lawsuit that the federal agency has filed against Amazon, which became thethird-biggest ad platform in the United States in 2018. Amazon sets its advertising prices using an auction system, in which companies bid on different types of ads and where they appear. In practice, the winning advertiser is only supposed to pay a cent more than the second-place bid. But the lawsuit claims that “in 2018, Amazon began secretly manipulating its auction results to increase its ad prices.