Google Ad Changes Leave Marketers Flying Blind, Expert Says

Alphabet Inc.’s Google quietly made changes to its advertising platform that significantly limits the amount of information marketers have about where their spending is going, according to an expert called on behalf of the federal government in an ongoing antitrust trial against the search giant.

“Google controls the rules and influences the outcomes of its auctions and these auctions are a black box to advertisers,” said Kinshuk Jerath, a marketing expert at Columbia Business School, who testified in federal court in Washington as part of the US Justice Department’s case.

In September 2020, Google changed what information it provides ...