Checking Whether Yahoo Finance Adjusts Historical Volume for Splits

Summary

The document addresses whether Yahoo Finance adjusts historical share volume for stock splits. It describes a practical check using Nike data around a two-for-one split: compare the reported volumes before and after the split and ask whether post-split figures appear doubled to reflect the larger share count. The cited answer concludes that volume is normally adjusted, based on those displayed observations.

This is an illustrative check of one data source and one corporate action, not a full specification of Yahoo Finance’s adjustment policy. The excerpt does not explain the adjustment formula or establish how other securities, dates, or historical data versions are handled. Traders using volume histories should treat the example as evidence for the case shown and verify the vendor’s conventions for their own instrument and period.

Key ideas

• The document asks whether Yahoo Finance adjusts historical trading volume for stock splits.
• It uses Nike data around a two-for-one split as an example for comparing volumes across the event.
• The cited answer infers that volume is normally adjusted because post-split volume is not roughly doubled.
• The example alone does not establish the provider’s policy across all securities or periods.

Tags

# Is the historical volume data from Yahoo-Finance adjusted for splits?


# Is the historical volume data from Yahoo-Finance adjusted for splits?












I have been looking for an answer on the Internet for this question for a while, but I could not find anything.

I understand that the price data of the historical data from Yahoo-Finance is adjusted for splits. Is the volume adjusted, too?

If it is not, the average volume should be accordingly higher after each split, because there are a lot more (or less) shares around. Or do I miss something?

## Answer by userid is i (score 3, accepted)

https://quant.stackexchange.com/a/39178

I believe the volumes are normally adjusted. Here is the yahoo data around Dec 23 2015 when Nike did a 2:1 split:

Dec 30, 2015 64.36 64.40 63.17 63.25 61.49 5,817,900

Dec 29, 2015 64.31 64.48 64.02 64.26 62.48 6,708,600

Dec 28, 2015 63.21 63.88 62.80 63.81 62.04 8,704,400

Dec 24, 2015 64.55 64.73 62.15 63.18 61.43 13,890,800

Dec 24, 2015 2/1 Stock Split

Dec 23, 2015 68.12 68.19 63.91 64.36 62.57 28,659,700

Dec 22, 2015 65.74 65.93 64.91 65.93 64.09 7,163,700

Dec 21, 2015 64.84 65.15 64.31 64.90 63.10 4,486,300

This shows the transaction volume after Dec 23 is not around double the earlier amounts, so it was adjusted.

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This summary was written by Stratmill's research agent from the original; it is not a copy of the source.