At the best of times, Macau's gaming stocks are not for the faint-hearted. But even by their standards, what happened last week was frightening.
About HK$190 billion in market capitalisation was wiped out of the top five gaming stocks in a matter of four days, all based on a couple of rumours.
More shockingly, while more than a week has gone by, the regulator has not intervened, leaving investors in the dark.
The triggers for the sell-off were two news reports that surfaced on April 23.
The Macao Daily ran an advertisement for junket company Kimren saying the firm "will not be held responsible for liabilities incurred due to Huang Shan's actions".
Huang is said to be a Kimren stakeholder. Soon, word of Huang disappearing with a huge sum began to spread. According to some, he had spirited away anything between HK$8 billion and HK$10 billion.
The same day, the Macau Daily Times reported that the wife of Cheong Chi-tai, an owner of listed junket company Neptune Group, had been detained by Hong Kong police in connection with a money-laundering investigation.
Interestingly, the market did not respond to the news until April 25, when gaming stocks began to fall. The drop deepened on Monday as Credit Suisse issued a report with details of the rumours.
Citing "channel check", the report said Kimren operates VIP tables in Melco Crown's Altira, MGM Macau and Galaxy Entertainment's StarWorld.
Any responsible regulator would have been on its feet by then - for two reasons.
First, all gaming stocks had dropped dramatically, with some shedding 4 to 5 per cent on Monday alone. Most news and research reports were blaming the rumours.
Second, at least four listed companies had figured in the rumours. They include Neptune, which has already been linked to a money-laundering investigation.
Granted, Hong Kong's regulators may not have the resources to ascertain the veracity of the rumours emanating in distant Macau. In that case, they should at least have asked related companies whether their businesses and financials would be affected.
Yet, with more than 10 per cent of their market value wiped out, none of the gaming firms has said anything so far.
There is a third reason why our regulators should have got involved - HK$10 billion is simply too big an amount for a credible rumour. Where would the absconder find so much cash?
Could it have come from a casino? From time to time, casinos do extend credit lines to junkets so that they can use the money to draw betting chips for customers. But it is difficult to imagine how a medium-sized junket like Kimren could get a HK$10 billion credit line from a casino.
One of the listed junkets, which runs 82 VIP tables in major casinos in Macau, says it has a rolling turnover of about HK$40 billion per month. A credit line of HK$10 billion is far too much when seen in that light.
And even if any casino did lend HK$10 billion to one junket, it is hard to imagine a single partner would be able to withdraw such a huge sum given that the credit line would be used by other partners and their subordinates at the same time.
"Besides, if I drew the full line, do you seriously think the casino would not check with my partners?" an industry source said.
So could the money have come from the customers rather than the casinos? Gamblers do occasionally park some cash with junkets to enjoy extra perks, for example HK$900,000 in cash for HK$1 million worth of chips.
The time lag between the cash-in and chips-out is, however, very short. One would need a group of customers to bring in a lot of cash in a very short time to be able to run away with HK$10 billion.
Of course, one should never underestimate the loot accumulated by corrupt mainland officials, and their penchant for gaming. Yet, even if one of them did park HK$10 billion cash with a junket, it would hardly affect the casinos.
Then could the money have been pooled by the shareholders of the junket? Again, you don't need HK$10 billion of cash investment to run a junket business. Listed junkets in general have an annual profit of about HK$400 million to HK$600 million. Why would shareholders pool HK$10 billion for that?
There are simply too many holes in the rumours and too many missing links in the entire episode.
Other than the extension of a credit line to a junket that subsequently collapsed, none of the above scenarios would have any significant impact on a casino's bottom line.
Neither do any of the rumours fully account for the four-day-long sell-off.
Then, was the nosedive a result of herd behaviour or was it a planned manipulation? That's for our regulators to find out.
In the meantime, the least they can do is ask the companies to speak up.