Speculators bagged as much as HK$300,000 profit per car park space at Festival City in Tai Wai, selling the slots within a day or two of buying them.
Cheung Kong Holdings (0001), the project's developer, sold a total of 514 car park slots at prices ranging from HK$980,000 to HK$1.3 million on Saturday, netting HK$600 million.
Within 24 hours, at least 40 buyers had resold their slots for profits ranging between HK$30,000 and HK$300,000.
By last night, another 20 buyers had sold their slots at prices ranging from HK$180,000 to HK$230,000 higher than they had paid barely 48 hours earlier.
Cheung Kong stressed on Saturday that only residents of Festival City were eligible to buy the car park slots.
Still, around 30 slots remain on the market, agents said. "The asking price for a parking space purchased for HK$1.3 million is now HK$1.6 million," said Adrian Ng Cheuk-yin, an account manager at Festival Home Property Agency.
Also, a total of 20 car parking spaces - sold on Saturday - have already been rented out at HK$3,800 to HK$4,700 per month, fetching a yield of about 4 percent, compared with HK$3,500 sought by Cheung Kong earlier.
About 30 spaces, asking as much as HK$5,000 per month, are still available for rent.
Most banks currently offer a mortgage of up to 50 percent to buy a parking space, with the repayment period of up to 20 years. Some banks, however, do not offer such loans.
But the 50 percent is just a reference guideline from the Hong Kong Monetary Authority.
The regulator said earlier that no specific rules are needed for loans to buy car park slots because they will not affect people's livelihood and most banks stick to lending half of the slot's value, which is not that risky.
Professor Eddie Hui Chi-man, a member of the government's Long-term Housing Strategy Steering Committee, said the frenzy over car parking spaces is growing fast especially after the government placed tightening measures on the residential market.
This has caused speculators to switch to investing in the non-residential market, especially parking spaces, the cost of which is relatively modest.
Edward Yiu Chung-yim, former University of Hong Kong assistant professor of real estate and construction, believes the sudden jump in parking space transactions is mainly caused by developers.
Property firms released a significant number of slots on the market after the government's latest cooling measures, Yiu said.
But he warned of the potential risks in this market, saying most investors continue to buy these spaces even when they see the rental yield is declining in the hope that the rents will go up.
Some areas of the secondary property market, meanwhile, remains bullish, especially Tai Koo Shing.
A three-room unit on a middle floor sized at 907 square feet was sold for a record high price of HK$13.88 million or HK$15,303 per square foot.
The price is 16 percent above the market level.