Cboe has amended its options rules to give firms more precise control over which extended sessions can execute an order. The filing creates “GTH Only” and “GTH and RTH Only” instructions, expands the windows in which orders can be accepted for queuing, addresses Curb Trading Hours on shortened trading days and makes designated primary market-maker quoting obligations apply by relevant session.[1][3]
The change matters because an order that is valid during Global Trading Hours does not necessarily belong in the later Curb session. A single generic extended-hours flag can create unwanted exposure when the product moves from overnight trading into regular hours and then into Curb. Session-specific instructions let the sender state that boundary in the order rather than relying on cancellation timing.[1][2]
How the new session instructions behave
Order instruction and end-of-session treatment
| Instruction | Eligible sessions | What happens to an unexecuted order |
|---|---|---|
| GTH Only with Day | Global Trading Hours only | Cancelled at the end of the GTH sessionSource 2 |
| GTH Only with GTC or GTD | GTH only across eligible trading days | Moves to the GTH queuing book for the next GTH opening, subject to instructionsSource 2 |
| GTH and RTH Only with Day | GTH and Regular Trading Hours, not Curb | May continue into RTH; cancelled after RTHSource 2 |
| GTH and RTH Only with GTC or GTD | GTH and RTH, not Curb | Can continue into RTH and later queue for the next GTH sessionSource 2 |
| No eligible extended-session instruction | Depends on class, routing and the sender’s other instructions | Must not be assumed to participate in every sessionSource 1Source 4 |
The rules also allow earlier queuing: no earlier than 6 p.m. Eastern on the previous day for GTH-eligible index options, and no earlier than 6 a.m. for other classes, at times Cboe determines. On shortened trading days, the curb session for eligible options follows regular trading for 15 minutes. These are session rules, not a statement that every option is available in every period.[2]
Designated primary market-makers must enter opening quotes for each session to which they are appointed. That makes the session assignment important for both the market-maker obligation and the broker’s handling of an order waiting for an opening rotation.[2]
The filing became effective through the exchange-rule process, while product implementation is communicated through Cboe notices. The key operational task is to map each client instruction to the correct session flag, cancellation rule and queuing state. The rule gives brokers more control; it also makes a mistaken default more visible because the permitted sessions can now be expressed explicitly.[1][3]
Sources & further reading
- SR-CBOE-2026-078: GTH and Curb Trading Hours amendments U.S. Securities and Exchange Commission · 7 Oct 2026 · Accessed 30 Oct 2026
- Cboe rule text for GTH Only and GTH and RTH Only U.S. Securities and Exchange Commission · 7 Oct 2026 · Accessed 30 Oct 2026
- SEC rulemaking page for SR-CBOE-2026-078 U.S. Securities and Exchange Commission · 7 Oct 2026 · Accessed 30 Oct 2026
- Cboe options trading hours Cboe Global Markets · Accessed 30 Oct 2026