Extended-Hours Data on a Chart
Whether a chart includes premarket and after-hours trading changes its bars, its gaps and every indicator computed from them.
MadStockAlerts Research · Updated August 28, 2026
What to take away
- Including extended hours removes visible gaps by filling the space with thin trading.
- Indicator values differ between the two settings because the inputs differ.
- Extended-hours bars are formed by far fewer participants.
- The setting should be stated whenever a level is quoted from an intraday chart.
- VWAP is affected directly, because the setting defines its accumulation window.
MAD Academy Training Video · 0:45
The Setting That Invents Gaps
Hiding extended-hours trading creates gaps where trading actually happened, and turning it on moves every level on the chart.
This lesson is part of a Stock Alerts + Tools plan.
What the setting changes
With extended hours excluded, an intraday chart runs 9:30 to 16:00 and an overnight move appears as a price gap between the last bar of one day and the first of the next. With them included, the space is filled by thin premarket bars and the gap disappears from view.
Neither is wrong. The first shows the regular session as a distinct thing, which is how most participants experience it; the second shows every trade that occurred, which is a more complete record.
Scroll the chart sideways to see all of it.
- Extended hours shown
- Regular hours only
Indicators are affected
A 20-period moving average on a 5-minute chart covers 100 minutes of the regular session with extended hours off, and 100 minutes that may be mostly overnight with them on. The two lines are computed from different data and will not agree. The same applies to VWAP, whose accumulation window is exactly this setting.
This is a genuinely common source of disagreement between two people looking at the same security. Both are reading their platform correctly and the platforms are configured differently.
The thinness caveat
A premarket bar can be formed by a few hundred shares. Rendered at the same width as a regular-session bar, it looks equally significant and is not.
Overlaying volume makes the disparity obvious immediately, which is the simplest correction available: a chart with extended hours on and no volume pane is a chart that invites the mistake.
Stating the setting
Two traders discussing an intraday level with different extended-hours settings are looking at different charts. It is a small thing that causes a surprising amount of confusion, and naming the setting alongside the level removes it.
Why the two settings produce different levels
With extended hours excluded, a daily bar records the regular session only. A stock that reported after the close and traded up eight percent overnight shows that move as a gap between yesterday's close and today's open, and the overnight high never appears on the chart at all.
With extended hours included, the same move is a sequence of very thin bars, the overnight high becomes part of the record, and there is no gap. Every high, low and range in that window differs between the two charts, and so does everything computed from them.
| What is being read | Excluded | Included |
|---|---|---|
| The earnings reaction | A gap between two closes | A visible path, on thin volume |
| The high of the move | The regular-session high | Often an overnight print nobody could transact size at |
| A resistance level | Set by regular-session trading | Can be set by a few hundred shares at 4:30 a.m. |
| Average true range | Excludes the overnight move | Includes it, and widens accordingly |
Neither is the true chart. The regular-session view describes where the bulk of transacting happened; the extended view describes every price at which any transaction happened. Which is more useful depends entirely on whether the question is about consensus or about the full range of prices touched.
Picking a setting and staying on it
The strongest argument for a fixed setting is comparability. A level drawn on one setting and revisited on the other is being compared against a different series, and the discrepancy shows up exactly when it is least welcome, which is when price is near the level.
- Level and structure work is conventionally done with extended hours excluded, because a level is a description of where meaningful volume changed hands.
- Event analysis is conventionally done with extended hours included, because the point is to see how the reaction developed rather than only where it ended.
- Any indicator with a lookback longer than a few bars will differ between the settings, and the difference persists for as many bars as the lookback.
- Backtests and published records must state the setting, because the same rule tested on the two series is two different tests.
A practical consequence for anyone reading someone else's chart: a level that looks slightly wrong is often not wrong at all, it is drawn on the other setting. Establishing which one is being used costs a moment and explains most of these disagreements.