What is a sidecar?

A sidecar (temporary suspension of program trading orders) is a mechanism to reduce the impact of program trading on the cash market when futures prices change sharply.

For example, in the KOSDAQ market, if the KOSDAQ150 futures price moves 6% or more from its base price and the KOSDAQ150 index simultaneously moves 3% or more from the previous trading day, and this persists for 1 minute, program trading orders received from that point on are suspended for 5 minutes.