"Many mainland buyers bought lots of properties in Hong Kong when the market was red-hot three years ago," said Joseph Tsang, managing director at Jones Lang LaSalle. "But now they want to cash in as liquidity is quite tight in the mainland."
A spokesman for Sun Hung Kai said the current occupancy rate at Valais was 75 percent, and most of the second-hand units for sale were "looking for a good selling price and not eager to sell at deep discounts."
In a nearby development called The Green - developed by China Overseas Land & Investment - about one-fifth of the houses delivered at the start of this year are up for sale. More than half of the units, bought for between HK$18 million and HK$60 million, were snapped up by mainland Chinese in 2012.
China Overseas Land was not immediately available to comment.
"Some banks were chasing them (Chinese landlords) for money, so they need to move some cash back to the mainland," said Ricky Poon, executive director of residential sales at Colliers International. "They're under greater pressure from banks, so they're cutting prices."
(Read more: Hong Kong's housing market is 'least affordable': survey)
In West Kowloon district, an area where mainland Chinese bought up close to a quarter of the apartments in many newly-developed estates, some Chinese landlords are offering discounts on the higher-end, three- to four-bedroom apartments they bought just a few years ago.
This month, a Chinese landlord sold a 1,300 square foot (121 square meter) apartment at the Imperial Cullinan - a high-end estate developed by Sun Hung Kai in 2012 - for HK$19.3 million, 17 percent less than the original price. The landlord told agents to sell the flat "as soon as possible," said Richard Chan, branch manager at Centaline Property in West Kowloon.
In the same area, a 645 square foot, 2-bedroom flat in the Central Park development was sold in just two days after the Chinese owner put it on the market at HK$6.5 million in what agents called the year's best bargain - the cheapest price for a unit of its kind over the past year.
"The most important thing for them is to sell as soon as possible," Centaline's Chan said. "In the past two weeks, those who were willing to cut prices were mainland Chinese. It is going to have some impact on the local property market, that's for sure."