Why Daily and Hourly Stock Volumes Can Differ
Summary
The discussion investigates why Yahoo Finance showed a daily trading-volume figure that did not match the sum of its hourly figures for a Japanese-listed stock. The explanation is that the daily number represented volume on the primary exchange, while the hourly series combined trades from the primary and non-primary exchanges. Because the hourly figures covered a broader set of venues, adding them did not reproduce the primary-exchange daily total.
The answer also describes the Tokyo trading schedule, including a midday break, which explains why no volume appeared in the reported 11 a.m. interval. It notes that the hourly presentation handled this interval incorrectly. The example shows that interval aggregates may use different exchange coverage and session conventions, so traders and researchers should check a data vendor's definitions before comparing or summing volume. The discussion is a single historical example and does not establish how the vendor reports every security or date.
Key ideas
- Daily and intraday volume figures may cover different exchanges.
- Hourly totals can exceed a daily total when the data combines primary and non-primary venues.
- Exchange trading sessions and midday breaks affect how intraday volume is grouped.
- Check vendor coverage and interval conventions before comparing or summing volume data.
- The explanation is specific to one reported security and date.
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# Discrepancy in stock volume values for different intervals for the same day on Yahoo Finance # Discrepancy in stock volume values for different intervals for the same day on Yahoo Finance everyone. Probably, someone else before me noticed that peculiar behaviour but I have not found any thread with a relevant title. Anyway, here is the case. I have attached a screenshot which displays the number of shares that have been bought and sold for 07.02.2020 of Square Enix Holdings. Here is the link->>>interval 1d As it can be observed volume value for the whole day is 1.53M. However, if interval is changed to 1H instead of 1D the following volume values hours-wise are displayed: 2/7 9 AM: 515.8K 2/7 10 AM: 229.1K 2/7 11 AM: No volume at all 2/7 12 PM: 942.4K 2/7 1 PM: 236.6K 2/7 2 PM: 1.56M If to sum it up, then the final value is 2.97 M. It would be great if someone clarifies it to me. Thanks in advance. ## Answer by amdopt (score 3, accepted) https://quant.stackexchange.com/a/51104 Regular trading hours for this stock on its primary exchange (in Tokyo) are from 09:00 JST - 11:30 JST, then it closes for 1 hour, then it reopens and trades from 12:30 JST - 15:00 JST. On top of that, trading runs continuously from 08:00 JST - 16:00 JST on non-primary exchanges. 1.53M is the volume according to the primary exchange (link below). The hourly data being displayed by Yahoo is a combination of primary and non-primary exchanges. The 11 a.m. hour is blank because the stock closes temporarily from 11:30 to 12:30 -- this is obviously wrong yet this is how Yahoo reports it nevertheless. It is probably a better idea for you to look for another data source. Looking through this post might be a good place to start: What data sources are available online? You can find data from the primary exchange here: Japan Exchange Group
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This summary was written by Stratmill's research agent from the original; it is not a copy of the source.