Schedule Update - Cboe Options to Introduce Stop Limit for Complex Orders and New Stop Complex Order Auctions

Overview (UPDATED)

Effective on a date to be determined, May 18, 2026, and subject to regulatory review, all Cboe-affiliated U.S. Options Exchanges will introduce Stop-Limit order functionality for complex orders. This enhancement will allow market participants to submit complex orders with stop-limit instructions, providing greater flexibility in managing risk and executing multi-leg options strategies. A new Stop Complex Order Auction (SCOA) mechanism will be used to expose orders for potential price improvement and maximize execution quantity. The future effective date will be communicated in an upcoming notice.

Technical Details

Currently, Cboe supports stop-limit orders for electronic single-leg options orders. Upon the effective date, stop-limit functionality will be extended to electronic complex orders. Stop-limit complex orders will be accepted during all trading sessions, but will only be eligible for triggering and execution during Regular Trading Hours (RTH).

A stop-limit complex order is a conditional order that becomes a limit order when triggered by one of the below configurable conditions. Only one trigger condition can be designated per order. The stop trigger conditions are as follows:

Net price of the complex strategy: an order will trigger when either the same side Market-Maker SBBO equals or betters the designated threshold price, or a trade in the same complex instrument occurs via COB, COA, AIM, SAM, or PAR at or better than the designated threshold price.
Underlying price: an order will trigger when a designated threshold price of the underlying security is either (i) at or above the underlying price or index level or (ii) at or below the underlying price or index level. For (i) the underlying price designated must be higher, and for (ii) the underlying price designated must be lower, than the current value of the equity same side NBBO or index level. If not, the order will be rejected.
1. Equity: triggers when the underlying security bid (ask) is equal to or higher (lower) than the designated stop price, or a trade occurs at a price equal to or higher (lower) than the stop price.
2. Index: triggers when the underlying index level is equal to or higher (lower) than the designated threshold price. This trigger does not include any bid/ask component.

Note stop-limit complex orders having both SPX and SPXW leg components and designating the net price trigger condition will only trigger if a trade occurs at or better than the designated threshold price.

SCOA Functionality

Once triggered, the order(s) will initiate a new SCOA. The SCOA message format will be identical to a COA message. If a single limit order is triggered, the SCOA starting auction price will be the less aggressive of the order's limit price or the opposite side SBBO. If multiple limit orders are triggered, the SCOA starting auction price will start the auction at the less aggressive of either the most aggressive limit price of the orders in the bundle or the opposite side SBBO. At the start of the auction, an Auction Notification message will be sent, and auction responses will be accepted. Orders will be allocated using a new proprietary volume-maximizing auction allocation methodology.

Upon completion of the initial SCOA, any unfilled order(s) will iterate through additional SCOAs at incrementally more aggressive starting prices until all orders are filled, their limit price has been reached, or the current opposite side SBBO price has been used as the last auction start price. The starting price for each auction in the iteration process will be the least aggressive of:

The previous auction price, plus the exchange default drill-through amount
The most aggressive limit price on the remaining order(s)
The opposite side SBBO

Any unfilled order(s) after the most aggressive price has already been used in a SCOA will be sent to the Complex Order Book (COB).

Note the stop price can be modified before the order is activated, but not the stop price type (i.e., the trigger condition). Once a stop order has been activated, the stop price is no longer modifiable. If an order is already in an auction, an attempt to modify its stop price will be rejected.

Order Entry (UPDATED)

The order entry instructions listed below can be used in the New Order Multileg FIX message and the New Complex Order BOE message. Two new fields will be added to these messages to support stop-limit complex orders: the existing StopPx field (FIX Tag 99), and a new StopPxType field (FIX Tag 25026). StopPxType will also be included on Execution Report messages. Additionally, a new value will be added to OrdType (FIX Tag 40) on these messages. Note the existing SessionEligibility field (FIX Tag 22017), if required, must be set to R (Default) to indicate participation in RTH only for a stop-limit complex order to be accepted.

A new NewComplexOrderUSOptionsV2 BOEv3 message will be created to send stop-limit complex orders. The NewComplexOrderUSOptionsV1 BOEv3 message will be sunset on a date to be communicated in an upcoming notice July 20, 2026.

The table below summarizes these technical specification changes. Please see the specifications listed below for more details.


FIX Tag	Field Name	Req'd	Description
25026	StopPxType	N	Indicates what kind of stop price is being sent. L = Fixed limit price B = Fixed underlying bid price or index level (complex orders only) A = Fixed underlying ask price or index level (complex orders only)
99	StopPx	N	The trigger price for stop-limit complex orders. Required if OrdType (40) = 4. Only one trigger condition can be designated per order. The stop limit trigger conditions are as follows: Net price of the complex strategy Underlying price
40	OrdType	N	4 = Stop Limit

Testing Opportunities

This functionality is currently available to test in the Options certification environments.

Additional Information

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Resources

For more information, please refer to the following technical specifications:

Contact Information

Please contact the Cboe Trade Desk for support or with any questions.

Cboe Trade Desk: 913.815.7001 | [email protected]

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