One57, a 1,004-foot tower under construction in Midtown Manhattan, will soon hold the title of New York’s tallest building with residences. But without fanfare from its ultraprivate future residents, it is cementing a new title: the global billionaires’ club.

The buyers of the nine full-floor apartments near the top that have sold so far — among them two duplexes under contract for more than $90 million each — are all billionaires, Gary Barnett, the president of the Extell Development Company, the building’s developer, said this week. The other seven apartments ranged in price from $45 million to $50 million.

The billionaires’ club includes several Americans, at least two buyers from China, a Canadian, a Nigerian and a Briton, according to Mr. Barnett and brokers who have sold apartments in the building, at 157 West 57th Street. Mr. Barnett said that at least a few buyers were “significant Forbes billionaires.”