The lights are rarely on in the sky-high condos of Billionaires’ Row, and that’s not only because their owners are seldom in town—it’s because many are lacking buyers entirely. A new estimate by real estate appraiser Jonathan Miller pegs upwards of 40 percent of Billionaires’ Row condos as unsold.

These buildings are not new to market: They include Extell’s One57, which officially unveiled its listings over seven years ago, where Miller estimates nearly 50 apartments have yet to find a buyer. (Extell disputed this finding, telling the New York Post that One57 is “over 85 percent sold in units and over 90 percent sold in value.”)

Of the eight Billionaires’ Row-area supertalls surveyed in the report, Miller estimates that JDS Development Group’s 111 West 57th Street has sold the smallest percentage of its condos. An estimated 20 percent of the building’s 60 units have nabbed buyers, meaning 48 of the skinny supertall’s luxurious digs remain unclaimed. (Curbed has reached out to JDS for comment, and will update accordingly.) It’s followed by Aby Rosen’s 100 East 53rd Street, where Miller estimates 63 of the building’s 93 condos are unspoken for over three years after hitting the market.

Miller estimates Vornado Realty Trust’s 220 Central Park South is the most well-selling building of the bunch, with an estimated 80 percent (or 94) of its 117 condos either closed or in contract.

For-sale condos in the buildings reported on—which also include 432 Park Avenue, 520 Park Avenue, 53 West 53, and Central Park Tower—range in price from a $2.1 million for a studio at 100 East 53rd to nearly $64 million for a four-bedroom penthouse at 53 West 53, the New York Post found.

Prices in the buildings remain so high for a few reasons: Firstly, the cost of land acquisition, construction, marketing, and building maintenance all get factored into the condo costs. Secondly, such adept developers write clauses into their contracts that keep lenders from forcing them to drop prices in the events that appear to be playing out. (Read: glut.)

“When people come here from other parts of the country and from around the world, the first thing they want to see is Billionaires’ Row,” luxury real estate agent Dolly Lenz told the Post. “We toured them through the properties but many felt they were too pricey for the market — $7,000, $8,000 and $10,000 a square foot.”

In January, hedge fund billionaire Ken Griffin made history by closing on the most expensive sold home not only in New York, but in the United States—a 24,000-square-foot penthouse at 220 Central Park South for which he paid $238 million, or a bit over $9,900 per square foot.

Griffin plans to use the trophy property as “a place to stay when he’s in town,” a rep for Griffin said. And this, in a city where the demand for space in homeless shelters has increased 79 percent over the last decade.