Effective October 13, 2025, subject to regulatory review, Cboe BZX Options Exchange will introduce complex orders.

Currently, Cboe supports complex orders on Cboe Options (C1), C2 Options (C2), and EDGX Options Exchanges. Upon the effective date, subject to regulatory review, Cboe will support complex orders on all Cboe-affiliated Options Exchanges, including BZX.

Complex orders on BZX will be available to trade via the Complex Order Book (COB) in price-time priority allocation and via the Complex Order Auction (COA) mechanism in price, pro-rata allocation with Priority Quoter functionality.

COA Auction Notification messages on BZX Options will contain an obfuscated (zero) value for the Price field, which matches the behavior on C1 and C2 Exchanges.

Upon the effective date, subject to regulatory review, COA responders on BZX Options Exchange will get allocation priority up to the size of their quote at the National Best Bid and Offer (NBBO) if they are on the contra NBBO on any legs of the complex instrument at the start of the auction.

If on the NBBO on multiple legs at the start of the auction, the Priority Quoter allocation size will be based on the Market Maker’s largest size on any NBBO leg, regardless of the ratios on each leg. At each price level, complex orders and COA responses from Priority Quoters will trade with the COA order first, and the balance of the COA order will be allocated to contra-side interest on the leg books in time priority, then in pro-rata priority against other complex orders and COA responses.

If multiple Priority Quoter responders are on the NBBO and the combined size of the responses is greater than the COA order size, then the Priority Quoter responders will receive a pro-rata share based on their Priority Quoter allocation size.