stock exchange of Hong Kong

Market maker provides the liquidity to the market. If the market lacks of buyers and sellers, people can't trade their security at the fair value and great premium or discount may be required.
In Hong Kong, most of the major stocks have a lot of buyers and sellers. Therefore, most of the securities do not require of maket makers
For some of the securities... e.g. warrants. It already requires the issuers of warrant provides the liquidity to the warrant issued if it lacks of buyer and sellers.
For most of the cent stocks (仙股), it really lacks of buyer/sellers... However, it's quite difficult to implement the maket makers system, as it requires the maket makers bear the risk, especially those cent stocks contain high risk.

Your specific question should send email to Hong Kong Stock Exchange to ask
[email protected]
(Informations Services Centre of HKEX)