All six casino operators in Macau saw their share prices fall after an announcement that the maximum stay for mainland visitors on a transit visa will be cut from seven to five days.
Wynn China and Melco Crown Entertainment shares tumbled the most, losing 2.43 per cent, followed by MGM China, which fell 1.44 per cent. Sands China lost 1.39 per cent, Galaxy Entertainment dropped 1.13 per cent and SJM lost 0.94 per cent by yesterday's market close.
That compared to a 0.42 per cent drop on the benchmark Hang Seng Index.
Macau police said the restriction, which comes into effect on July 1, was intended to stop mainland tourists supposedly transiting through Macau from overstaying there.
"To avoid Chinese tourists holding Chinese passports who make use of transit to effectively stay in Macau and not go to their destinations, the Public Security Police Force decided to adjust the related control again," it said.
It is the second time in six years that Macau has reduced the maximum period of stay for mainland travellers. In 2008, the permitted stay was reduced from 14 days to seven.
Under the new rule, transiting mainland tourists who re-enter Macau within 30 days of a previous overstay will only be allowed to stay in the former Portuguese enclave for one day - down from the current two days.
If tourists overstay a second time they will be denied entry for 60 days - and if they are caught trying to enter within that time, the ban will be extended by another 60 days, police said.
One analyst who asked not to be named said: "I don't think it's a big deal, to be honest. I don't know why people are making a fuss. People don't stay more than two days on average, so if you go for seven days or five days, it shouldn't matter."
According to Macau Government Tourist Office director Maria Helena de Senna Fernandes, the average tourist stays 1.5 days.
Liang Jun, managing director of the Shenzhen-based Century Holiday International Travel Service, said the measures were simply a gesture by the Macau government to show it would not turn a blind eye to visa abuse.
"The measure will not affect regular tourists, because no regular mainland tourists would spend even the five days allowed in Macau after the new measure.
"It's targeting those who need to make frequent trips to Macau, usually sex workers or others making a living in the city's entertainment industry, as the new measure will drive up their costs," Liang said.
Bloomberg gaming analyst Tim Craighead said the tightening would have limited impact on revenues and visitation.
"It's yet another news item that transpired the last couple of months, along with the UnionPay issue and some earlier concerns on junkets, that have caused some angst in the marketplace, but the real underlying driver on the stocks right now is slowing revenue growth."
Craighead was referring to increasingly difficult year-on-year comparisons and a shift away from VIP business towards the mass market, which has weakened top-line numbers.
"We've had momentum slow, and rotation in the investor base away from growth and momentum investors.
"It's created a negative cycle and sentiment, where any news item that comes out, stocks get hit again," Craighead said.