BYX Exchange Mirrors Cboe ISO Rule Update
Published Date: 6/23/2026
Notice
Summary
Cboe BYX Exchange is updating its rules to let traders enter Intermarket Sweep Orders (ISOs) as hidden (non-displayed) orders and set clear price levels for when these orders can be matched with others. This change helps traders act faster and smarter in the market, potentially improving trading efficiency. The new rules could start soon after the SEC reviews them, affecting anyone who trades on BYX and possibly impacting trading costs and speed.
Analyzed Economic Effects
3 provisions identified: 3 benefits, 0 costs, 0 mixed.
Hidden ISOs Allowed on BYX
Cboe BYX will allow Intermarket Sweep Orders (ISOs) to be entered as Non-Displayed (hidden) orders. The change is proposed for implementation during the second half of 2026. If you trade on BYX, you can send ISO orders without displaying them, giving you a new option for hiding residual interest when executing across markets.
Non-Displayed Orders Can Re-Price Multiple Times
BYX will permit Non-Displayed Orders to re-price (slide) multiple times to more aggressive prices if the User elects that instruction. Each time a Non-Displayed Order is re-priced it receives a new timestamp, and the order will retain its original limit price regardless of the ranked price. The Exchange plans implementation in the second half of 2026.
Clear ISO Price-Level Rules by Session
The Exchange will codify when an ISO's limit price is considered available for other orders to join or for resting orders to re-price. Under proposed Rules 11.9(d)(1)-(3): during Regular Trading Hours (9:30 a.m.–4:00 p.m. ET) the ISO limit price is considered available; during the Early Trading Session (4:00 a.m.–8:00 a.m. ET), Pre-Opening Session (8:00 a.m.–9:30 a.m. ET), and After Hours Trading Session (4:00 p.m.–8:00 p.m. ET) the ISO limit price will not be considered available; an ISO entered during Regular Trading Hours may remain available into After Hours if eligible. Implementation is planned for the second half of 2026.
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Key Dates
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Next: 2026-12524 — Self-Regulatory Organizations; Cboe BZX Exchange, Inc.; Notice of Filing of a Proposed Rule Change To Amend Rule 11.9(d) To Permit an Intermarket Sweep Order (“ISO”) To Be Entered as a Non-Displayed Order and To Establish the Price Level at Which the System Will Consider an ISO Available for Other Orders To Be Entered
Cboe BZX Exchange is updating its rules to let a special type of order called an Intermarket Sweep Order (ISO) be hidden from view when entered. They’re also setting clear price rules for when these orders can be matched with others, and allowing hidden orders to adjust prices more aggressively. This change affects traders using the BZX Exchange and aims to make trading faster and smarter, with the new rules kicking in soon after approval.