In the latest sign that NYC's ultra-high end property market is on the verge of imploding after a wave of overly aggressive development, another luxury condo at Manhattan's One57 tower, a member of "Billionaire's Row," a group of high-end towers clustered along the southern edge of Central Park, has gone into foreclosure - the second in the span of a month.

The 6,240-square-foot (580-square-meter) full-floor penthouse in question, One57's Apartment 79, sold for $50.9 million in December 2014, making it the eighth-priciest in the building.

"It's probably the most-expensive foreclosure we've ever seen in luxury development," said Donna Olshan, president of high-end Manhattan brokerage Olshan Realty Inc. "I don't know of a foreclosure that's larger than that."

According to Bloomberg, the shell company that purchased the property took out an unusually large mortgage and promised to repay in full a year later.