The Midtown office tower that inspired the 1968 hit song Mony Mony has sold for much less mony  than its previous owner paid for it.

Yellowstone Real Estate forked over a mere $185 million — a massive $420 million haircut from how much the famed Mutual of New York tower fetched a decade ago — to purchase the remaining debt on the near-empty office building now simply called 1740 Broadway, according city Department of Finance records.

Blackstone had shelled out $605 million to buy it from Vornado in 2014 — or nearly  $1,000 per square foot for the 621,000 square-foot 1950-vintage, Deco-style tower between West 55th and 56 streets.

A $308 million loan on the property was sent to special servicing in 2022.

The fire-sale price reflects the crisis in the investment-sale market for commercial properties, where some office values have tumbled by up to 50%.

But 1740 Broadways discount was perhaps the most severe to date for an aged but still viable, recently renovated Midtown tower.

Insiders were divided over how bad an omen the lowball price is for future sales.

CBRE vice-chairman Stephen B. Siegel told The Post that Blackstones $605 million purchase price in 2014 simply reflected the mood of the time, when property values were at all-time highs and several Manhattan trophy buildings traded for more than $2 billion.

Blackstone had a good plan for it, but things didnt work in their favor, said Siegel, who was not involved in the 1740 Broadway deal.

Facing exits by Victorias Secret owner L Brands and law firm Davis+Gilbert that left  most of the tower vacant, Blackstone spent tens of millions of dollars to modernize 1740 with a handsome new lobby, tenant amenities and a popular new restaurant, Iris.

But the pandemic doomed Blackstones re-leasing efforts.

The private equity firm handed back the keys in 2022.

One major dealmaker told us at the time that Blackstone’s “purchase price was bananas for an older building in the West 50s that needed a lot of work.

The source added, They wanted in the $80s per square foot in a secondary location. The loan terms left them no wiggle room to ask for less.

Sources told the Commercial Observer that Yellowstone, led by Isaac Hera,  is considering a residential conversion.

“The price reflects the value in that context,” Woody Heller, founding partner of Branton Realty and a longtime investment-sale specialist, told The Post.

Heller cited “strong residential demand and the building’s proximity to  Central Park” as driving a conversion plan.

A Blackstone rep told the Commercial Observer the loss of 1740 was a rare instance that didnt affect its $600 billion portfolio.

Yellowstone and Blackstone didnt respond to The Posts requests for comment.

The tower’s storied legacy includes serving as the inspiration for Tommy James & the Shondells as the band struggled to come up with a catchy title for their song. The group was staying nearby when James caught sight of the giant MONY initials that were once illuminated in red near the top of the tower.

We were about to throw in the towel when I went out onto the terrace, looked up and saw the Mutual of New York building,” he later explained.

I said, Thats gotta be it! … Its almost as if God himself had said, ‘Heres the title.’

Vornado replaced the MONY sign with one that simply said 1740 in 2007.