Effective December 15, 2025, Cboe Options Exchange (C1) will introduce Wide Market Protection (WMP) functionality for SPX and SPXW options to reduce the risk of orders executing at adverse prices.

When triggered, WMP will display eligible market and marketable limit orders at an initial Benchmark Price and iterate them toward more aggressive prices in 200 millisecond (ms) intervals using existing drill-through functionality. WMP will be initiated when an eligible order is received into the Book when the NBBO is deemed wide.

Stop and stop-limit orders held by the Exchange that are marketable upon election, as well as new inbound marketable orders, will be subject to WMP handling with some exceptions.

Certain order types, including Immediate or Cancel orders, Intermarket Sweep Orders and all Market Maker (MM) quotes and Market Maker orders with a Time-in-Force of Day, will not be subject to WMP and will enter the book unabated.

Protected orders will automatically move to match more aggressive same-side Market Maker quotes.

WMP will operate during all trading sessions except the final 30 seconds of the Regular Trading Hours session and the final 30 seconds of the Curb Trading Hours session.

A market or marketable limit order becomes a protected order upon receipt into the book when the NBBO is deemed wide based on the WMP Determinant. The same applies to stop/stop-limit orders held by the Exchange that become marketable when triggered and the post-trigger NBBO is wide.

Cboe will initiate WMP upon the following events:

• A market or marketable limit order is received when the NBBO is deemed wide.
• A stop/stop-limit order held by the Exchange becomes marketable when triggered and the NBBO immediately after the triggering event is deemed wide.

Once WMP is triggered:

• The order is displayed at its Benchmark Price.
• Existing drill-through functionality (Rule 5.34(a)(4)) iterates the displayed price every 200 ms. The drill-through interval for SPX/SPXW prior to WMP was 1000 ms.
• The order continues iterating until reaching its limit price or until fully executed or until cancelled by the entering firm.