Effective October 26, 2026, all Cboe-affiliated U.S. Equities Exchanges will introduce separate Fat Finger Protection limit settings for non-Regular Trading Hours (non-RTH) sessions, including Early Order Acceptance, Early Trading, Pre-Market, Post-Market, and the future Overnight Trading Session. Fat Finger Protection allows customers to have their orders rejected if the order’s limit price is deemed too aggressive relative to the opposite side of the NBBO.

Currently, Fat Finger Protection settings apply to all trading sessions on the Cboe Equities Exchanges. On the effective date, the existing Fat Finger Protection settings will only be applicable to the Regular Trading Hours session, and a new group of settings will be added for non-RTH sessions, including Early Order Acceptance, Early Trading, Pre-Market, Post-Market, and the future Overnight Trading Session. Non-RTH session settings will be pre-populated to match each customer’s existing configuration.

Fat Finger Protection settings can be configured using the Port Controls tool within the Cboe Customer Web Portal or via Secure Web API using the setClient command in the U.S. Equities Port Controls service.

This functionality is currently available to test in the U.S. Equities certification environments.