U.S. DOJ Readying Google Antitrust Lawsuit Over Ad-Tech Business

U.S. antitrust officials are preparing a second monopoly lawsuit against Alphabet Inc.’s Google over the company’s digital advertising business, according to a person familiar with the matter, stepping up the government’s claims that Google is abusing its dominance.

The Justice Department has accelerated its investigation of Google’s digital advertising practices and may file a lawsuit as soon as the end of the year, said the person, who declined to be named because the investigation is ongoing. No final decisions have been made and the timing could be pushed back.

Google touched a low in extended trading on the news, ...