Shares of several Singaporean real estate developers tumbled on Friday, a day after a surprise government move to tighten curbs on property in a bid to cool the market.

On Thursday, Singapore authorities raised an additional stamp duty on property purchases by five percentage points for some home buyers and tightened housing loans limits.

The city-state’s housing market has been recovering since the third quarter of 2017 after nearly four years of price declines. Private homes prices have risen by 9.1 percent over the past year.

“To me, it is quite shocking,” said Christine Li, senior director of research at real estate services firm Cushman and Wakefield in Singapore. “There will be a knee-jerk reaction in property stocks.

Property companies have been buying land in government sales or in collective sales, where they purchase existing apartment blocks for re-building.

Authorities have been cautioning as early as November against an “excessive exuberance” in the property market.

A fresh warning came this week, from the head of the Monetary Authority of Singapore, Ravi Menon, who said the recovery in the property market was welcome but should not veer too far from economic fundamentals.

Based on the land parcels that were sold in the past two years, there are some 28,000 to 30,000 private residential housing units that could be developed for launched in the next two years, said Nicholas Mak, executive director at ZACD.

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