On 24 February 2014, SGX will add circuit breakers as a new market safeguard. The reason for introducing circuit breakers is given as:
In the event of rapid price movements, investors may not have time to make informed decisions when they trade.
Given that the circuit breaker cooling-off period only lasts for 5 minutes, I am not too sure how this mechanism is going to be useful for most investors.
Circuit breakers will initially apply to:
When a trade is placed at a price that is more than 10% away from the reference price, circuit breakers are triggered and a five-minute cooling-off period occurs. During this period, trading can only take place within a price band 10% above or below the last reference price.
The reference price of a security is determined in different ways depending on which part of the trading session a transaction in that security may be occurring. For example, the first reference price of each trading session is either the opening price that day, or if nothing is traded, the last traded price (or closing price) of the previous session.
Thereafter, the reference price is the last traded price as at five minutes before, or if nothing is traded, the first reference price that day. If circuit breakers are triggered for a security, and trades occur during the cooling-off period, the reference price after the cooling-off period is the last traded price as at five minutes before. If no trade occurs during a cooling-off period, the first trade after the cooling-off period is not subject to any circuit breaker.