What is the market volatility regulation mechanism (VCM)

When the price of the stock / futures contract reaches the trigger price range, the market volatility regulation mechanism (VCM) will be triggered, starting a five-minute cooling-off period, so that the transaction will be limited to the specified price limit, and the normal transaction will be restarted in 5 minutes.

[Trigger price range]
Securities market: reference price changes by more than ±10% Derivatives market: reference price changes by more than ±5% Reference price: last transaction 5 minutes ago

[Market scope]
Hang Seng Index of State-owned Enterprises Index (81 at present) and related index futures contracts (currently 8).

[Applicable time period]
Applies only to continuous trading periods, excluding 15 minutes in the morning and the first 15 minutes in the afternoon and the last 15 minutes in the afternoon. During the 5-minute cooling-off period, the transaction price can only be within the trigger price limit, that is, ±10% / ±5% of the reference price (depending on the market).