What it means
Stock exchanges have a regular session, but many shares also trade in a pre-market period beforehand. During those hours prices respond to company announcements, economic data and events in other time zones.
The indicator takes the latest pre-market prices of the 100 index members and combines them using the index method. The result is a figure comparable to the official index, which lets investors see roughly how far the market might rise or fall at the open.
It is published by Nasdaq and typically displayed on financial websites and news terminals alongside futures prices. Pre-market trading usually involves fewer participants, wider gaps between buying and selling prices, and bigger swings caused by small orders.
A single large trade in one heavy member can move the indicator a good deal. For this reason, the indicator can be misleading and the official opening level often differs from it.
Professionals use it together with futures contracts on the index, which trade for nearly 24 hours a day. Futures give a more liquid view of expectations, while the indicator reflects actual trading in the underlying shares.
For a manager or founder, the practical use is context. If a sector peer reports weak results overnight and the indicator is sharply lower, you may expect pressure on your own share price or on investor sentiment at the open.
The indicator also has limits as a record. It is not a tradable product by itself, and it is replaced by the official index once the regular session starts.
Analysts therefore treat it as a snapshot of early sentiment and not as a data series to build a model on.
In practice
Real-world examples.
Example
A fund manager arrives at her desk after a major technology company reports strong earnings overnight. The pre-market indicator is up 1.2%, and she decides to delay selling some holdings until the market opens. She wants to see whether the early gain survives the first half hour of normal trading.
Example
A chief executive of a listed software firm checks the indicator before an investor call. A sharp fall of 2.5% warns him that analysts may be nervous, and he prepares extra reassurance on cash flow. He also asks his investor relations team to prepare answers on the sector's results.
Example
A day trader notices that the indicator moved 0.8% on very low volume. He treats the move with caution because thin trading can exaggerate the numbers and reverse at the open. He waits for volume to build before placing an order.
Formula
Calculation
Pre-market change (%) = (Indicator value - Previous official close) / Previous official close x 100
The previous official close is the last official index level from the prior regular session. Suppose the Nasdaq 100 closed at 18,000 and the pre-market indicator shows 18,180 an hour before the open.
Pre-market change = (18,180 - 18,000) / 18,000 x 100 = 180 / 18,000 x 100 = 1.0%.
If the indicator instead read 17,640, the change would be (17,640 - 18,000) / 18,000 x 100 = -2.0%, signalling a weaker open.Case study
Seen in the real world.
Fernhill Capital is an illustrative, fictional trading firm that used the pre-market indicator as a trigger for early orders. If the indicator showed a gain above 1%, it bought index funds before the opening bell.
On one morning the indicator showed a gain of 1.4% on thin volume after a rumour about one large member. When the regular session opened, the rumour was denied and the index opened only 0.2% higher, leaving the firm with a loss on its early purchases.
In this illustrative story the head of trading changed the rule to require both strong volume and confirmation from futures. The lesson was to treat the indicator as one input and not a signal to act on alone. The firm also began logging the gap between the indicator and the opening level each day, which showed that large early moves often shrank.
Watch out
Common mistakes.
- Treating the pre-market figure as the official index level, when it is only an estimate before the session starts.
- Ignoring trading volume, when thin volume makes the indicator less reliable.
- Relying on it alone without checking futures prices, company news and overall trading volume.
Questions
People also ask.
When is the indicator published?
It is shown in the hours before the regular session opens, once pre-market trading begins. Check the provider's schedule for exact times, since they can change.
Is the indicator the same as index futures?
No, futures are separate contracts that track expectations, while the indicator is calculated from pre-market prices of the actual shares.
Does the indicator always predict the open?
No, it often differs from the actual opening level, especially when volume is low. Large news items can also change the picture in the final minutes before the bell.
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