Cboe BYX Bans Traders from Trading with Themselves in Auctions
Published Date: 3/31/2025
Notice
Summary
Cboe BYX Exchange is updating its rules to let users use Match Trade Prevention (MTP) when placing Periodic Auction Orders. This change helps traders avoid accidental self-trades and makes auction orders clearer and safer. The update kicks in once approved, improving how orders are handled during auctions without extra costs.
Analyzed Economic Effects
4 provisions identified: 2 benefits, 2 costs, 0 mixed.
MTP Now Allowed on Periodic Auction Orders
If you trade on Cboe BYX and place Periodic Auction Orders, you can now add Match Trade Prevention (MTP) instructions to those orders. MTP prevents orders that share the same Unique Identifier from executing against each other and can cancel the older, newer, or smaller order depending on the MTP modifier; using MTP is optional.
MTP Can Be Temporarily Bypassed During Auctions
When a Periodic Auction is in progress, the BYX System may temporarily bypass an inbound MTP instruction on a Continuous Book order so that the Continuous Book order can be processed instead of being cancelled. The bypass applies only upon entry during the Periodic Auction and normal MTP enforcement resumes after the auction ends.
Inbound MTP Auction Orders May Be Canceled
If a Periodic Auction is in progress and an inbound MTP Periodic Auction Order would, but for MTP, execute against a resting MTP Periodic Auction Order participating in that auction, the System will cancel the inbound MTP Periodic Auction Order. This cancellation is intended to avoid disrupting a Periodic Auction once initiated.
Minimum Quantity Ignored When MTP Applies During Auctions
When a Periodic Auction is in progress, the System will ignore a Minimum Quantity instruction appended to an MTP Periodic Auction Order or an MTP Continuous Book Order; Minimum Quantity behavior will be applied at the end of the Periodic Auction Period per Rule 11.25(b)(2)(C). In examples, the System ignores MIN and applies MTP, which can result in cancellation of the Minimum Quantity order.
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