Hong Kong's de facto central bank bought HK$3.93 billion on Thursday after the local currency hit the weak end of its trading band against the US dollar.
The city's currency is pegged within a range of 7.75 to 7.85 per greenback, and the Hong Kong Monetary Authority steps in when the currency reaches either end to maintain the peg.
The aggregate balance, the key gauge of cash in the banking system, will shrink to HK$82.55 billion on Friday.
The HKMA has intervened seven times since June 26, buying a total of HK$91.11 billion to defend the currency peg.
STAFF REPORTER
