HONG KONG — Even by the standards of Hong Kong, where the ups and downs of the stock market rival events at the horse track as a spectator sport, three recent flameouts have been spectacular.

A Chinese marble miner named ArtGo plummeted by 98 percent in one day. A Chinese automaker-turned-education-company called China First Capital dropped 78 percent . Another education firm, Virscend, was restrained by comparison, falling 33 percent in one day.

The tumbles over the last two weeks have little to do with the pro-democracy demonstrations that have subsumed Hong Kong for five months and sometimes caused gyrations in the local market. Instead, they point to more persistent problems in the market, which has long been Asia’s financial capital . Regulators let some dubious practices slide. Rules stifle naysayers who might rein in gullible or overly exuberant investors.

As a result, bubbles inflate regularly in Hong Kong, with sometimes alarming speed. Then they pop, often leaving small investors with nothing but air.