Cboe’s port-controls specification permits separate regular-session and non-regular-session fat-finger limits from 26 October 2026. The change applies to its four US equities venues. These controls screen order-entry prices against a reference; they do not guarantee a fill or protect an existing position from loss.[1]
Equities percentage ceilings in the port-controls specification
| Item | Detail |
|---|---|
| Limit price below $1 | 500%Source 1 |
| $1 to below $10 | 50%Source 1 |
| $10 and above | 20%Source 1 |
| Specification default for an unconfigured equities control | DisabledSource 1 |
The official specifications differ for sub-$1 orders: the port-controls table permits a maximum of 500%, while the Secure Web API describes executionCollarNonRth1 as an integer from 1 to 75. The published text does not resolve that discrepancy. An API implementation needs Cboe to confirm the accepted range before relying on the larger portal maximum.[1][2]
The same document describes different default protections for options. The equities “disabled” statement must not be extended to those options settings.[1]
Operational significance
A broker should reconcile the settings for each port, venue and session with its own client controls. Testing both buy and sell orders around price-band boundaries can expose incorrect assumptions. A syntactically accepted configuration also needs monitoring: the presence of a control in a specification does not establish that a particular customer connection has enabled it.[1][2]
Sources & further reading
- Titanium US equities/options Web Portal Port Controls specification Cboe · Accessed 27 Oct 2026
- Titanium US Secure Web API: non-RTH executionCollar parameters Cboe · Accessed 27 Oct 2026