At least a quarter of New York condos built since 2013 were unsold in September, and Midtown West, which includes Hudson Yards, had the second highest share of unsold inventory, with 45 percent.

“Maybe they didn’t do as well as they hoped for,” said Kael Goodman, the founder of Marketproof, a real-estate data company in Brooklyn. The condos at 15 Hudson Yards have sold for an average $2,785 a square foot, a 7 percent discount from peak pricing in 2017, when they asked for more than $3,000 a square foot, according to Marketproof. Related maintains, though, that the building has sold at an average $2,900 a square foot.

There were certainly less successful buildings that began closings this year, he said, but the project still has a large share of unsold units more than three years later. And next year could bring more obstacles to the condo market, including political uncertainly and recent tax changes.

There are still about 13 acres of land to be developed in the second phase of the project, which will likely include several new residential buildings, an office complex and a public school, much of it to be built on top of a platform over the rail yards. Construction was planned to be completed by 2024, but Related is no longer providing a timetable for its completion.

“The issue is that the consumer feels the market is going to decline further,” said Pierre E. Debbas, a managing partner at Romer Debbas, a real-estate law firm that has represented condo buyers in Hudson Yards.

“What’s going to create urgency? A reduction in pricing or concessions,” he said. “That’s it.”

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