The Hong Kong Monetary Authority is HK's central bank.
The Bank has intervened to buy HKD, amount circa 11.7bn HKD, sell USD to support the Hong Kong dollar.
The HKD trades in a band set by the HKMA, and defended, when needs be, by them. With the super-strength USD playing havoc with other FX the HKMA has once again been in the market.
You can clearly see the lower bound for the HKD in the chart above, upper bound for USD/HKD.
