ETH (extended / overnight hours)
ETH (extended trading hours, also called the overnight or Globex session) is the portion of a futures session that trades while the underlying cash market is closed. On CME index futures it runs from the evening reopen in Chicago until the next day's cash open, and it produces the overnight high and low that many traders carry into regular hours.
Senzoukria · Glossary · Updated September 2026
Definition and boundaries
The CME electronic session for equity index futures opens in the Chicago evening and runs into the next afternoon with a short daily pause. The stretch between that evening open and the cash-market open is the extended session. In most charting vocabularies it is written ETH, or simply 'overnight' or 'Globex'.
ETH is not a separate instrument: the same contract, the same order book and the same tape continue. What changes is who is present. European and Asian hours bring a different participant mix, less resting size and, on ordinary days, a smaller share of the day's volume. On days with major overseas news or scheduled US data before the cash open, the picture can invert.
Reading the overnight tape
- Each print is a larger share of its price level, so imbalance flags and absorption patterns appear with less size behind them.
- The overnight high and low are the extremes of the ETH window; they are widely watched at the cash open because they summarise the inventory built before US participants arrive.
- Thin books mean a single order can move price several ticks; a liquidity heatmap in these hours shows fewer, brighter bands.
- A quiet feed and a broken feed look the same on screen overnight. Check the connection before reading silence as absence of trades.
In Senzoukria
The Overnight High/Low indicator, in the Profiles & levels group, draws the extremes of the bars between the session open at 17:00 Chicago time and the RTH open, then projects them across the rest of the session. The RTH open is a parameter expressed in minutes after the session open; the default corresponds to 08:30 Chicago time for CME equity indices, and the offset stays correct through daylight-saving changes because those happen on Sunday, outside the session.
The indicator emits nothing when the loaded session has bars on only one side of the boundary. An overnight high with no regular-hours bars afterwards has nothing to project onto, and a missing value is shown as missing rather than as zero.
Common mistakes
- Reusing RTH-tuned imbalance thresholds overnight and reading the resulting flood of flags as unusual aggression.
- Forgetting the daily pause: the overnight window is not continuous with the previous afternoon's close.
- Building the overnight range from a partially downloaded history and treating it as complete.
- Assuming every vendor starts ETH at the same minute; session templates differ.
Related
- Overnight High/Low indicator
- RTH (regular trading hours)
- CME trading hours and daily break
- NQ and MNQ order flow settings
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Frequently asked questions
- Why is the overnight high/low watched at the cash open?
- Because it marks the boundary of the inventory accumulated while the cash market was closed. Whether price accepts or rejects those extremes in the first regular-hours bars is one of the simplest ways to see whether the new participants agree with the overnight auction. It is a reference level, not a prediction of direction.
- Does the extended session include the daily break?
- No. CME index futures pause for an hour each afternoon in Chicago; that hour has no quotes and no trades. The extended session begins when trading resumes after the pause and ends at the next regular-hours open.
- Is there an ETH session on crypto perpetuals?
- Crypto venues do not close, so there is no exchange-defined extended session. Any overnight window on a crypto chart is a convention the analyst picks, usually tied to a US or Asian clock, and should be labelled as such.