A bipartisan group of senators intends to introduce legislation as soon as this week that would force Alphabet Inc.'s Google to sell off parts of its lucrative advertising technology business, according to two people familiar with the matter.

The bill, led by Sen. Mike Lee, a Utah Republican, would bar companies with more than $20 billion in digital advertising revenue from owning the tools to help buy and sell online ads and operating the exchange where those transactions occur.

The measure would also compel companies with more than $5 billion in digital advertising revenue to act in customers' best interests and provide greater transparency on data collection, the terms of winning bids and the fees they charge, which would have major implications for Google, Amazon.com Inc. and Meta Platforms Inc., which owns Facebook and Instagram.

Democratic Sens. Amy Klobuchar of Minnesota and Richard Blumenthal of Connecticut are also sponsors on the bill, said the people, who declined to be identified because the plans to introduce the bill are not yet public.

Representatives for Google, Amazon and Facebook and a spokesperson for Lee didn't immediately respond to requests for comment.

Google's dominance in the advertising technology market — the tools used to buy, sell and display the online ads that help fund many websites — has been the subject of intense antitrust scrutiny. Attorneys general from 15 states plus Puerto Rico sued Google in December 2020 for allegedly monopolizing the market. That effort, which is being led by Texas, accuses Google and Facebook, the No. 1 and No. 2 players in online advertising, of reaching a secret illegal pact in 2018 to divide up the market for ads on websites and apps.

Both Facebook and Google deny that their agreement was illegal.

The Justice Department has been investigating Google's advertising technology business since 2018, and European authorities have opened their own competition probes into the Google-Facebook deal, nicknamed Jedi Blue.

Google is expected to generate $174.81 billion in net digital ad revenue this year, an increase of 17.3%, according to Insider Intelligence analyst Paul Verna. That gives it a 29% share of the worldwide digital ad market. Facebook is second with a 21.4% share.

Leah Nylen reports for Bloomberg News.

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