What do an eye clinic operator, a satirical magazine publisher and a bubble tea maker have in common?

They all had eye-popping initial public offerings on the Hong Kong stock exchange, as retail investors sent their shares soaring. In recent months, companies including ophthalmic services provider C-MER Eye Care Holdings, bubble-tea company B & S International, contemporary furniture retailer Ulferts and magazine proprietor Most Kwai Chung have all listed on HKEX and seen their valuations leap.

In the case of Most Kwai Chung, publisher of 100Most magazine aimed at millennials, its shares surged as much as 880 per cent, before halving by the end of its first trading day. This company, a typical example of so-called penny stocks, listed at HK$1.20 (US$0.15) and closed at HK$6.38.