HDB resale prices dipped 0.5 per cent last month compared with December last year, along with a 31.4 per cent drop in sales volume, according to SRX Property flash estimates released yesterday.

Resale prices slipped by 2 per cent compared with January 2017 and have fallen by 13 per cent from the peak in April 2013.

Based on SRX Property estimates, 1,089 HDB resale flats were sold last month, down from 1,587 in December last year. Resale volume fell by 8.7 per cent from 1,193 in January 2017.

The decrease in resale deals reflects how people are busier as they return to work after the December school holidays, said Mr Chris Koh, director of real estate agency Chris International.

"Historically, the market is quieter in January, with school reopening and people going back to work," he said, adding it usually picks up after Chinese New Year.

Also, some buyers and sellers are waiting to see how the new HDB resale portal works, he said.

The portal, launched on Jan 1, promises to cut transaction time for buying and selling HDB resale flats from 16 weeks to eight weeks.

Compared with the peak of 3,649 units in May 2010, the HDB resale volume last month was down by 70.2 per cent.

According to the estimates from SRX Property, January resale prices fell by 2.3 per cent for three-room flats and 1.2 per cent for five-room flats. But that of four-room units and executive flats bucked the trend, going up by 1.3 per cent and 0.4 per cent respectively.

Last month, HDB resale prices in mature estates dropped by 1.8 per cent, while prices in non-mature estates edged up by 0.5 per cent.

Prices in mature estates have gone down by 2.3 per cent year on year from January 2017, while in non-mature estates, the figure has shown a 1.8 per cent decline.

Last month, the overall median Transaction Over X-Value (TOX) was negative $3,000, down $100 from December last year. TOX measures whether buyers are overpaying or underpaying compared with SRX Property's computer-generated market value.

While the TOX for three-, four-and five-room units were all negative, that for executive flats was a positive $2,000.

The areas in demand look to be in Kallang/Whampoa and Geylang, with flats there posting the highest median TOX of $17,000 in January. In contrast, Jurong East posted the most negative median TOX of $16,000, followed by Bukit Merah at $9,000.