Cboe Europe has informed its participants of the upcoming introduction of the volatility auction functionality for securities trading on its Regulated Market segment (REGM), for release to the

production environment effective Monday, September 29, 2025, subject to external assessments.

The volatility auction functionality will be introduced within the DXE and CXE platforms for securities trading on REGM only and will be used to determine the price of an instrument in place of the static collar mechanism following a manual trading halt or automated volatility halt.

Cboe volatility auctions use the same mechanism as existing opening and closing auctions but are initiated by price movements rather than scheduled at a specific time. If an order on a REGM-traded securities executes more than 10% away from Cboe’s reference price, Cboe will immediately initiate a volatility auction with a duration of 5 minutes plus any auction extensions. The price determined by the auction will become the new Cboe reference price.

Dual listed REGM securities will continue to use static collars.

In addition to auctions triggered by volatility, Cboe will employ the same auction mechanism to re-open a primary listed Cboe REGM security following a regulatory halt. This is to ensure that trading resumes in a manner that supports a fair and orderly market.

Opening auction orders that are not executed at the end of the auction will be transferred to Cboe’s lit book and lit orders that remain active at the end of the trading day will automatically be included in the closing auction.

REGM Auctions will now accept iceberg orders, but only the display quantity will receive priority.

There is no impact on the Periodic Auction Book (PAB) or change to PAB functionality.

Cboe Europe has also announced the upcoming introduction of Multi-Day Order functionality for securities trading on its REGM, including Good-Till-Cancel (“GTC”) and Good-Till-Day (“GTD”) order functionalities. These will be released to the production environment effective Monday,

November 3, 2025, subject to external assessments.

• GTC and GTD orders are now fully supported for REGM securities, with orders re-entered at system startup until expiry (maximum 90 days).
• GTC or GTD orders with a multiday expiry for non-REGM securities will be rejected.
• New SubLiquidityIndicator values for Multi-day GTC and GTD orders are available for BOE sessions, allowing participants to receive done-for-day and restatement messages. When enabled, participants must request the SubLiquidityIndicator bit field on order acknowledgments.
• New TradeLiquidity Indicator (9730) values for Multi-day GTC and GTD orders are also available and can be enabled for FIX sessions and drop copies.

Effective immediately, these changes are available on DXE and CXE Cboe Certification (UAT) test environments.