Why Historical Adjusted Stock Prices Change After Dividends

Summary

The document explains why a historical adjusted closing price downloaded from Yahoo Finance can differ between downloads made at different times. The quoted example compares two values for Microsoft on the same historical date, then points to the provider’s adjustment policy: prices account for applicable stock splits and dividend distributions using split and dividend multipliers under CRSP standards.

Because later cash distributions affect the adjustment factors applied to earlier prices, a new download can show revised historical adjusted closes even when the underlying trading record for those dates has not changed. The response cites Microsoft dividends paid after the earlier download as a concrete reason the adjustment series could differ. This matters when building return histories or comparing backtests across data vintages: adjusted-price data can be revised as corporate actions accrue. The document does not describe the exact calculation or establish that every historical difference comes from dividends, so users should check the provider’s adjustment definitions and corporate-action records.

Key ideas

• Adjusted closing prices incorporate stock splits and dividend distributions.
• Later corporate actions can change adjustment factors applied to earlier prices.
• Historical adjusted-price downloads may therefore vary by retrieval date.
• Check the provider’s adjustment methodology when constructing return series.

Tags

# Why are Yahoo's "Adj closed" data changing over time?


# Why are Yahoo's "Adj closed" data changing over time?












I downloaded MSFT historical data from Yahoo Finance a year ago and re-downloaded it today again. I turns our the two datasets are different.

E.g., today I got Adj Close of MSFT for `1986-03-19: 0.066604` In the dataset from a year ago, I got Adj Close of MSFT for `1986-03-19: 0.068892`

These two numbers are very similar but not the same. Other numbers changed, too. What's the reason for this change of historical data?

## Answer by gene_clipper (score 1)

https://quant.stackexchange.com/a/31132

Yahoo prices are adjusted for all applicable splits and dividend distributions. Data is adjusted using appropriate split and dividend multipliers, adhering to Center for Research in Security Prices (CRSP) standards.

Yahoo finance provides a knowledge base article on the adjusted close:

https://help.yahoo.com/kb/SLN2311.html

Since your last download, Microsoft (MSFT) has had the following cash dividends since November 2015: 11/15/2016 Cash 0.39, 8/16/2016 Cash 0.36, 5/17/2016 Cash 0.36, 2/16/2016 Cash 0.36, 11/17/2015 Cash 0.36

Shown in full with attribution under the source's licence. Licence: CC BY-SA 4.0 (Stack Exchange)

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