CME session open (17:00 Chicago)

The CME session open is the moment the exchange's electronic session resumes each trading day, at 17:00 Chicago time for equity index and most other Globex futures. It is the natural anchor for session-based calculations on futures: a session cumulative delta, a session VWAP or a session high and low all start counting from that minute, not from midnight.

Senzoukria · Glossary · Updated September 2026

Why the futures day starts in the evening

CME Globex reopens for the next trading day at 17:00 Chicago time, after the daily pause that follows the afternoon close. From the exchange's point of view the trade date of everything printed after that reopen is the following calendar day, so a Monday session actually begins on Sunday evening in Chicago.

This is not a quirk to work around; it is the definition of the session. Settlement, daily volume and open interest are all computed on that trade date. A chart that cuts the day at local midnight splits one exchange session into two pieces and glues the tail of one onto the head of the next.

What anchors on the session open

  • Session cumulative delta: the running sum of per-bar delta (ask volume minus bid volume) starts at zero at each 17:00 open.
  • Session VWAP: the volume-weighted average price accumulates from the same minute.
  • Session open level: the open price of the first bar of the session, which is the day's open for a CME future, not the midnight or cash-open price.
  • Session high and low, initial balance and opening range: each is measured from the session anchor unless an RTH offset is applied.

In Senzoukria

Every session-scoped study in the desktop application uses the 17:00 Chicago open as its canonical anchor. Session CVD (the cumulative-session-delta indicator in the Delta group) resets at each session open across the whole loaded history, not only for the current session. The Session Open level in Profiles & levels plots the open of the first bar of each session across that session.

The same anchor drives Session VWAP and the 'Session open' choice of Anchored VWAP, Session High/Low, Opening Range and Time-of-Day Volume, which matches a minute of today's session with the same minute of previous sessions. The scripting template described as 'Delta summed from the CME session open, reset each day' exposes the convention to user scripts. The built-in cumulative delta panel is the exception: its anchor is a panel setting and it does not certify complete coverage since the opening.

Common mistakes

  • Anchoring a session delta at the start of the loaded chart or at local midnight, then comparing it with a session-anchored value from another platform.
  • Quoting the cash-open price as 'the open' of a futures contract.
  • Loading history that starts after 17:00 and treating the resulting cumulative delta as the full session's.
  • Forgetting that the Sunday evening open belongs to Monday's trade date.

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Frequently asked questions

Is the session open the same for every CME product?
Most Globex financial futures, including equity indices, reopen at 17:00 Chicago time, but agricultural and some other product groups follow their own schedules. Check the trading hours page for the specific product on the exchange's site before assuming the equity-index timetable.
What happens to the session open when daylight saving changes?
The open stays at 17:00 Chicago local time, so it moves by one hour in UTC and in any time zone that changes on a different date. Because the US switch happens on a Sunday morning, outside the session, an offset measured in minutes from the session open stays valid all year.
Why does my session CVD differ from another platform's?
The most common causes are a different anchor (midnight, chart start or RTH open instead of 17:00), a different trade-classification rule, or a history that does not cover the whole session. Line up the anchor and the coverage first; the trade classification rarely explains a large gap on its own.

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