Sydney’s trophy home market is fast grinding to a halt as stock levels shrink to all-time lows and buyers are forced to negotiate on off-market deals.

The number of high-end properties in the slightly more affordable prestige market throughout the eastern suburbs and north shore have also dried up leaving agents dumbfounded at the dramatic turnaround in activity levels compared with the boom-time turnover of previous years.

There are currently only four properties on Sydney Harbour advertised for sale in the $30 million-plus market, the cheapest of which has expectations of selling for more than $37 million.

Property developer Phil Wolanski's penthouse at 8/27 Billyard Avenue, Elizabeth Bay is up for auction.

The number of new listings to hit the Sydney market in the four months to May was 24,058, down 12.3 per cent from the 27,418 new listings in the same period last year, according to Domain chief economist Dr Andrew Wilson.

But nowhere is the lack of stock more pronounced than in the trophy and ultra-prestige markets.

Palm Beach, Sydney’s iconic northern beaches prestige suburb, saw an almost 50 per cent decrease in new property listings in April 2016 compared to April last year, new data from Domain Group shows.

The drop in listings from 12 to six reflects a chronic shortage of quality, exclusive properties, according to Dr Wilson.

“The prestige market on the northern beaches has by-and-large collapsed,” he said.

Elaine, in Point Piper, which is owned by the Fairfax family is one of the few ultra-prestige homes on the market.

While Mosman, a “bellwether suburb” with higher-priced prestige properties, also saw a decrease in new listings from 58 to 53, Manly was the stand-out suburb with a shortfall of properties on the market, according to Dr Wilson.

The beachside suburb, with a median house price of $2,600,000, saw listings tumble from 39 to 21.

Across the city in Darling Point, where the median house price is $5,460,000, there was a “significant” drop in listings from nine in April 2015 to six in April this year.

Some suburbs did however see a slight increase in listings.

“There are of course seasonal aspects, like Easter rolling into school holidays and an Anzac Day long weekend disrupting the auction market momentum,” Dr Wilson said.

“This is not a return to the global financial crisis of a few years ago, this is about there being almost nothing left on the shelf to sell,” said Bill Malouf, of LJ Hooker Double Bay.

The owners of 13, 13a, 15 and 15a [behind] Coolong Road, Vaucluse, banded together to sell to a Sydney businessman for $70 million.

“That shortage is under-pinning prices in the upper market so vendors who are selling are getting fair, market value for their homes.”

The recent sale of four Vaucluse properties on Coolong Road for almost $80 million to Menulog co-founder Leon Kamenev to form one waterfront estate is being cited as a classic example of what happens in a tight market.

“When someone at that price level can’t find the sort of housing they want, they will go door knocking to see how much it will cost to pry people out of their harbour-front homes,” said Elliott Placks, the Ray White Double Bay agent who negotiated on the deal.

Another Coolong Road resident cashing in on the current demand is property developer Phillip Wolanski, who on Friday  put his vast Elizabeth Bay penthouse on the market.

The penthouse includes garaging for nine cars.

Previously owned by Hermes Australia boss Karin Upton Baker and her husband, property developer Gary Baker, it was sold by a mortgagee company two years ago for $5.91 million to Wolanski and Melbourne-based Sam Alter and Stewart Baron.

The strata plan for the penthouse has since been increased from 600 square metres to a whopping 1000 square metres of exclusive title and includes garaging for nine cars.

“We were asking $10 million for it off-market until recently, and we’ve been inundated with enquiry,” said Jason Boon, of Richardson and Wrench Elizabeth Bay.

6-8 Carrara Rd, Vaucluse is also on the market.

It goes to auction on June 9 for $8 million, although sources question whether Wolanski may still withdraw it and resume his earlier plans to live in it.

McGrath’s Ben Collier said 2016 has proven to be a highly disruptive year for the market, with Easter falling two weeks before school holidays and a federal election called for July.

“The higher you go up the price bracket the more the markets are grinding to a halt and the more off-market deals are being done,” said Collier.

One factor agents point to is the lack of downsizer options available for empty nesters.

“If we get a listing, buyers are all over it, the problem is people are nervous of selling because where are they going to go?” said Brendan Warner, of Raine and Horne Mosman.

“The lack of stock is begetting a lack of stock, and that’s across all markets in Mosman.”

A lack of top end real estate for sale is forcing deep-pocketed buyers to push through purchases in record time.

At 26 Vaucluse Road, Vaucluse, the residence of Goldman Sachs executive director David Nolan and his wife Anita was sold for $12.5 million only a week after the historic home was listed.