Technology Questions

What are the FIX/BOE protocol changes?

Order Entry

• The system uses SessionEligibility (FIX Tag 22017) to distinguish which sessions an order or quote may trade. SessionEligibility = A includes the Curb trading session on Quote Update message and all other messages where it is an optional field. SessionEligibility = B indicates orders are eligible for the RTH and Curb sessions.
• While not required to be sent by the member, TradeDate (FIX Tag 75) is sent on Execution Reports back to the Member. A TradeDate occurring after 8:15 p.m. ET and before midnight will denote the trade date as occurring on the next business day since that is the date such trades will process for clearance by the OCC.
• Market orders and stop/stop limit orders are not supported during GTH or Curb sessions.

Cancellation of Orders

• Cancel Order messages for persisted orders are permitted up until 15 minutes after the close of the Curb session. On U.S. holidays, Cancel Order messages for orders that will persist in between trading segments are permitted for 15 minutes after the first GTH session ends at 11:30 a.m. ET.

Carried Orders

• The Multi-Segment Holiday Day Order Handling port attribute enables Members to designate if Day orders are cancelled or preserved across holiday trading segments comprising a single trade date. This port attribute does not apply to quotes. Quotes are cancelled at the conclusion of the first GTH session.

FLEX Order Handling (FIX only)

• FLEX orders are allowed during GTH and Curb, with the exceptions of FLEX-% and FLEX-DAC orders which are only allowed during RTH.
• FLEX symbol creation is enabled for the Curb trading session, but symbol creation is disabled during GTH. Effective July 13, 2026 FLEX symbol creation will be allowed for GTH-Eligible proprietary index and GTH-Eligible multilist options starting at 7:30 a.m. ET.