American Media Inc., the country’s largest tabloid publisher whose chairman is a close ally of President Trump, controls almost the entire supermarket checkout rack after new acquisitions announced on Friday.

A.M.I. said it had bought In Touch, Life & Style, Closer and 10 other titles from Bauer Media, expanding a celebrity-news portfolio that already included The National Enquirer, Us Weekly, Globe, OK!, Star and Radar Online.

The move gives the company, led by David J. Pecker, almost full ownership of the print gossip market, leaving People magazine, owned by the Meredith Corporation, as one of the only major glossy gossip titles not under Mr. Pecker’s umbrella. (TMZ, the dominant gossip player online, has come under the ownership of AT&T with its purchase of Time Warner.)

Mr. Pecker is a Bronx native and a longtime Trump friend. A former top executive of Mr. Trump’s casino business sits on A.M.I.’s four-member board of directors. During the 2016 campaign, its flagship National Enquirer devoted glowing covers to Mr. Trump’s triumphs, aggressively attacked his rivals and made its first-ever presidential endorsement.