Fewer flat owners are jumping at the chance to sell their Housing Board unit once they can, as weak resale prices make it more worthwhile to hold on.
Two years ago, almost one in five of those who turned eligible to sell their flat - having stayed for the minimum five years - promptly did so within the year.
But last year, amid a cooling market, only 5.5 per cent who had met the minimum occupation period (MOP) did so.
Of 8,521 possible flats, 470 changed hands within a year of meeting MOP, HDB figures showed.
Given the lacklustre resale market overall, it is no surprise that few newly eligible flats are changing hands too, said Chris International director Chris Koh.
HDB resale transactions fell to just 18,100 last year, the fewest since 1997.
Experts said that flat owners were holding on to their homes in the face of low resale prices and cash over valuation (COV).
Resale prices fell 0.6 per cent over 2013, the first annual decline since 2005.
As for COVs, these cash premiums could once hit six figures for a choice unit. But they had fallen to a median of zero in February and were removed from the resale process in March.
"Flat owners whose homes are ready for resale realise they can no longer make a windfall from high COV when they sell their flat," said R'ST Research director Ong Kah Seng.
Then, there may be flat owners who would like to sell, but cannot afford to upgrade.
After all, selling "is possible only if they can buy another property", said Mr Koh.
And tighter rules have made it harder to get a sufficient loan to upgrade, he noted.
Since August, the maximum tenure for HDB home loans has been cut, and buyers can use only up to 30 per cent of their income to service their mortgage, down from 35 per cent.
Those hoping to upgrade to private property face similar curbs.
"Thus many of them decided to stay put," said Mr Koh.
OrangeTee head of research Christine Li notes that the gap between HDB resale prices and those of mass-market condominiums has also widened.
Over the past year, the price index for mass-market homes has actually risen 4.8 per cent, according to Singapore Real Estate Exchange figures, she said.
Flat owners "who had upgrading plans previously have to rethink their plans".
And as the quality and design of new HDB flats and estates improve, upgrading to a resale flat or private property becomes a less attractive option, added Mr Ong.
Finally, even if more of the newly eligible wish to sell their flats, they may not find buyers.
Resale demand has fallen, partly since the August rule change requiring new permanent residents to wait three years before buying an HDB flat.
Ms Li said: "Some HDB sellers could take up to several months before finding a buyer."