SAPINOVER // 24H Trading · Infrastructure diagnostic · Beta

What to ask before the first overnight ticket

A question map for OMS, EMS, brokers, venues, data and post-trade. It sits underneath the published 24-Hour Markets FAQ: the wiring, the FIX fields and the session mechanics that decide whether an institutional order survives 8:00pm, 9:00pm, midnight, 4:00am and the weekend.

Companion to FIX 24-Hour Markets FAQ v1.0
Sources checked vendor, venue and regulatory documents, Nov 6, 2026
Go-live Dec 6 evening, trade date Dec 7
BETA

We are opening this to institutions now, ahead of the Dec 6 go-live.Buy-side desks, brokers, OMS and EMS vendors, venues and data providers: run your own stack through it, tell us what is wrong or missing, and help shape the next release. Write to research@sapinover.com.

Venue-native GTCMostly absentBlue Ocean, Bruce, MOON and Cboe expire or treat it as DAY
Overnight value of tag 336Three dialects6 + 625=3 · OVN · PN
ATS quotes on the SIPNeverADF has no quoting participants · direct feeds or OBBO all night
NSCC 24x5 trade captureLiveSince Jun 29, 2026 · Sun 8pm to Fri 8pm
Exchanges and SIP on 23/5Dec 6, 9:00pmOvernight ATSs from 8:00pm · daytime ATSs 7:00am and 9:30am
Describe your stack first. The clock, the simulator and the questionnaire all use it, and the session clock drives the FIX inspector.
§ 00 Example firm pre-filled, edit to match yours · saved in this browser only

Your stack

Describe the setup you actually have. The clock overlays your reset and batch windows, the questionnaire flags the items your own answers already put at risk, and the simulator runs an order through the same constraints.

Daily FIX reset window (ET)
to
Weekend restart
OMS end-of-day batch lock (ET), blank if none
to
Broker desks enabled for your flow
Venues your routes reach
0 / 40

Overnight hours your stack can actually trade in the model week, out of 40 (8:00pm to 4:00am, Sunday to Thursday nights). Removes your reset and batch windows, the hours before your weekend restart, and hours with no reachable venue.

    § 01 Model week: Sun Dec 6 to Sat Dec 12, 2026, the first 23/5 week

    Session clock

    Every failure on the call traced back to a clock assumption. Scrub through the week to see which venues are live, whether the SIP is publishing, when FIX sessions should reset, and what trade date an execution carries.

    Sun Dec 6, 2026 · Eastern Time
    8:30pmET
    ATS-only windowATSs trade. SIP and exchanges join at 9:00pm.
    Next boundary
    Overnight session Regular hours Pre and post-market SIP publishing NSCC capture FIX reset, logon, margin Pause, maintenance or batch risk
    Execution now · trade date (75)-
    Settlement (T+1)-
    TransactTime (60), UTC-
    ET calendar date-

    Week view · click any hour to jump there
    § 02 Click a node

    The order wire, hop by hop

    Eight parties touch one institutional overnight order. Each badge counts the P0 questions that party has to answer. Select a node to see the messages it sends, where 23/5 breaks it, and the questions to put to it.

    intent 35=D 35=8 D/G/F 35=8 59, 336 35=8, 75 quotes quotes capture 336=OVN T+1 settlement · TradeSuite confirms allocate affirm drop copy 35=8 Market data venue feeds · SIP from 9:00pm · vendor composites PM / Trader mandate · intent · cover OMS parents · compliance · EOD EMS / FIX routing · TIF · session ID Broker / SOR desk · algos · access Venue ATS 8pm · exchanges 9pm Custody / PB allocation · financing NSCC / DTCC 24x5 capture, live
    § 03 Uses your stack settings

    Lifecycle simulator

    Send one institutional order into the model week and watch what each boundary does to it: acceptance, partial fills, trade dates, the venue's expiry, and who, if anyone, re-creates the residual the next session. Fills are illustrative; the boundaries are not.

    Entered (ET)
    30% of the open quantity
    Inject

    Reset window, batch lock, weekend restart and child re-creation come from §00.

      § 04 Timestamps follow the session clock

      FIX message inspector

      The child order as a broker gateway sends it to the venue, rebuilt for the destination and the moment you pick. BodyLength and CheckSum are computed live. Values shown in red are not published for that destination: request its final dictionary.

      Destination
      Buy-side intent
      Message

      At 4:00am

      § 05 From the Nov 6 primary-source pass, plus two daytime ATSs

      Venue matrix

      Venue labels are not interchangeable. Each row is what the venue's own documents say, with the evidence type, so you know what is filed versus what is merely announced.

      Show
      VenueHours (ET)GTC behaviorSession ID / datesConnectivityEvidence
      § 06 What the tape shows, hour by hour

      Data feeds: ATS plus SIP, all night

      The SIP never carries ATS quotes. The only path would be FINRA's ADF, which has no active quoting participants and runs 8:00am to 6:30pm. ATS prints reach the tape through the TRF, which pauses 8:00 to 9:00pm. So an overnight view needs the ATS direct feeds or an aggregator for the whole session, and nothing but those feeds between 8:00 and 9:00pm.

      0 quoting participants

      on FINRA's ADF, the only route for an off-exchange quote into the consolidated quote. ADF hours 8:00am to 6:30pm. (SR-FINRA-2026-015)

      21.2%

      of overnight ATS share volume executes between 8:00 and 9:00pm, inside the planned SIP and TRF maintenance window. (SEC staff memo, Aug 2026 data)

      9:00pm Sun to 8:00pm Fri

      TRF hours from Dec 6, with the 8 to 9pm pause. Today: 4:00am to 8:00pm, so every overnight ATS print waits for the morning tape. (SR-FINRA-2026-015, Notice 26-07)

      You can see8:00 to 9:00pm9:00pm to 4:00am4:00 to 9:30am9:30am to 4:00pm4:00 to 8:00pm
      Exchange quotes and prints on the SIPNoneSIP maintenance pause; exchanges closedFrom Dec 6Nasdaq, NYSE, Cboe EDGX, 24X overnight sessions. Form T prints, overnight bandsYesPre-market, no bands until 9:30YesRegular NBBO, LULDYesPost-market, no bands
      Overnight ATS quotesBlue Ocean, Bruce, MOONDirect feed onlyVenue feeds or an aggregator OBBODirect feed onlyNever on the SIP; the exchange NBBO omits themClosedATS sessions end 4:00amClosedClosed
      Overnight ATS prints on the tape (via TRF)HeldTRF paused; prints report after 9:00pm. Direct feeds show them liveFrom Dec 6Within 10 seconds via TRF. Today: not until 4:00am. Sunday 8pm to midnight was treated as a non-business day with prints suppressed from the SIP; confirm the Dec 6 treatmentYesOvernight batch and .W trades may report by 8:15am under Notice 26-07YesYes
      Daytime ATS printsOneChronos, IntelligentCrossClosedClosedOneChronos from 7:00amVia TRF; dark, no displayed quotesBothVia TRFClosedOneChronos reports only, to 5:00pm
      Reference price for bands and riskVenue-definedBlue Ocean: 20% band from a 7:30pm referenceSIP overnight bandsPublished from 9:00pm, cleared at 4:00amNo bandsLULDNo bands
      Aggregator · live

      Exegy Axiom OBBO

      Consolidated overnight BBO across Blue Ocean, Bruce and MOON, derived from each venue's L1. Individual venue feeds or the OBBO service; L1 or L2 by cross-connect at NY4/NY2. Blue Ocean live first, Bruce and MOON added in Q1 2026.

      Exegy, Feb 2026 and product page
      Aggregator · live

      dxFeed Aggregated Overnight Feed

      Normalized L1 quotes, trades, time and sales and summaries across Bruce, Blue Ocean and MOON, merged with regular sessions into one continuous schema.

      dxFeed, Apr 2026
      Aggregator · live

      ICE Consolidated Feed

      Streaming data from Blue Ocean, MOON, Bruce and OTC Markets Overnight, with FINRA-published prints and historical datasets.

      ICE Data Services product page
      Direct

      Venue feeds

      Each ATS publishes its own book. Direct gives you the venue's full depth and its own timestamps; you calculate the OBBO yourself and own the symbology and normalization.

      Blue Ocean, Bruce, MOON specifications
      To confirm

      Other vendors

      Bloomberg B-PIPE, LSEG Real-Time, Databento, Pico, BMLL (historical) and your EMS vendor's own feed. Ask each which of the three ATSs it carries, with quotes or prints only, and from what time.

      Not verified in this pass
      Question to settle

      Which price do your risk checks use at 8:30pm?

      If the OMS keys limits and bands to an NBBO, there is none. Decide whether the OBBO, a single-venue BBO or the 4:00pm close is the reference, label it, and test what rejects.

      Questions O10, M2, M5, M6
      § 07 Two separate problems hide behind "rollover"

      Session resilience

      The business-day batch cycle is one problem. The FIX session surviving a dropped connection with no quiet window is another. Recommended practice: complete resets between 5:30 and 7:00pm ET, log on and verify by 7:30pm, and keep 30 minutes of margin before the 8:00pm ATS open.

      APPROACH 1

      Concurrent sessions

      Works today

      Two live sessions, application picks the active one. Zero-latency failover, but in-flight status on the failed session is ambiguous and every firm writes the logic itself.

      APPROACH 2

      Reliable bearer layer

      Proposal

      Replace TCP/TLS under FIX with a redundant transport. No FIX spec changes, but a major build with unclear vendor appetite. No deployment found.

      APPROACH 3

      Extend FIX itself

      Proposal

      Pre-established standby session with 141=Y and a proposed Failover field, promoted by a Sequence Reset Failover (35=4). The most developed of the three. No vendor or venue ships it publicly.

      Initiator your gateway Active engine live sequence Standby engine 141=Y · Failover=Y Shared state store + sequences on failure: 35=4 Sequence Reset Failover gap recovered via NewSeqNo (36)

      Approach 3 as proposed in the FIX Continuous Markets deck. The one documented reset behavior found in the wild: 24X resets during its 8 to 9pm pause, not at midnight. QuickFIX/J documents a NonStopSession option, which is engine capability, not proof of adoption by any OMS or EMS.

      Sequence ceiling calculator · one session stream
      1,000msg/s

      Amber tick marks one 23/5 week (Sun 8pm to Fri 8pm, 120 hours). The 2,147,483,647 ceiling applies only where a component stores MsgSeqNum as signed 32-bit. Ask for the real type in the engine, store, parser and database.

      § 08 Score as evidence arrives · saved in this browser

      The questionnaire

      Framed the way the call landed: what to ask your counterparty and who owns the answer, not a prescription. Score each item on the evidence scale. The launch gate is every P0 item at level 3, tested in your own UAT chain.

      P0 at level 3 or higher
      0 / 0
      Launch gate blocked

      Unscored items count as level 0, unknown.

        Copy blocked by the browser. Select all and copy manually.

        0Unknown1Sales or roadmap claim2Released technical documentation3Tested in our UAT chain4Production-approved for our route
        § 09 Run with real versions, keep the traces

        Acceptance tests

        A vendor demo is not a test. Run these through the actual OMS, EMS, broker, feed, clearing broker and custodian, and keep message traces, order-state snapshots and sign-offs.

        TestScenarioPass conditionBoundary
        § 10 From the call and the research pass

        Why now, and where this comes from

        $15B+

        Record single-night notional across three ATSs, the Monday before the call.

        ~7%

        Institutional share of overnight volume today. The rest is proprietary and market-making flow.

        Dec 6

        Exchanges and SIP move to 23/5 at 9:00pm Sunday. First trade date: Monday Dec 7.

        2

        European exchanges planning 24-hour trading for some products: LSE and Deutsche Börse.

        Sources from the Nov 6 primary-source pass (links as supplied; re-check before configuring)
        1. FIX 24Hr Markets FAQ, v1.0, Oct 21, 2026
        2. FIX forum: US overnight session 23*5 FIX tags, Oct 2026
        3. DTCC: NSCC now live with clearing hours extended, Jun 29, 2026
        4. DTCC UTC 24x5 Trade Processing FAQ
        5. DTCC Important Notice A9689, Jan 7, 2026
        6. DTCC: 24x5 trading and T+1 confirmations, May 28, 2026
        7. Blue Ocean ATS FAQ
        8. Bruce ATS Form ATS-N amendment, 2025
        9. OTC Link MOON FIX Specification, v1.8.1, Mar 23, 2026
        10. Cboe Titanium U.S. Equities FIX Specification
        11. Nasdaq ETA2026-46
        12. NYSE Extended-Hours Trading FAQ, v3.0, May 2026
        13. 24X FAQs
        14. UTP Participant Input Specification
        15. CTA Extended Trading Hours FAQ
        16. Cboe One feed notice 62163, effective Nov 2, 2026
        17. FIX Session Layer Technical Standard, Jun 2020
        18. FIX Recommended Practices: 24x7 Sessions
        19. QuickFIX/J configuration
        20. OneChronos U.S. Equities ATS FIX 4.2 Specification and User Manual
        21. Imperative Execution (IntelligentCross) FAQ
        22. SR-FINRA-2026-015, TRF hours 9:00pm to 8:00pm; ADF status
        23. SR-FINRA-2026-005, overnight reporting exception (.W, 8:15am)
        24. SEC staff memo, Roundtable on 24-Hour Trading, Sep 2026
        25. Exegy Axiom OBBO and launch coverage, Feb 2026
        26. dxFeed Aggregated Overnight Equities
        27. ICE Consolidated Feed, overnight coverage
        28. Cboe EDGX Overnight Trading FAQ
        29. FIX Continuous Markets session-resilience proposal (D. Arnold)