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docs: explain default price adjustment and Close vs Adj Close (fixes #860) - #2992

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ValueRaider merged 2 commits into
ranaroussi:mainfrom
TTNAN:docs/adj-close-note-860
Oct 18, 2026
Merged

ValueRaider merged 2 commits into
ranaroussi:mainfrom
TTNAN:docs/adj-close-note-860

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@TTNAN

@TTNAN TTNAN commented Oct 11, 2026

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Fixes #860.

Per @ValueRaider's direction on the issue ("Better to resolve through documentation"), this adds a short "A note on price adjustment" subsection to the README, right after the Main components list:

  • Ticker.history() / yf.download() default to auto_adjust=True, so Close is already the adjusted close and no separate Adj Close column is returned in this mode
  • auto_adjust=False gives raw (unadjusted) OHLC plus an Adj Close column

Docs-only change, no code touched.

@arhancanli

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One wording problem in the new note: "Pass auto_adjust=False to get raw (unadjusted) OHLC values" isn't quite right. With auto_adjust=False the OHLC is still split-adjusted, because that is how Yahoo returns it; only Adj Close carries the dividend adjustment on top.

Checked against Yahoo's chart endpoint for AAPL around the 4:1 split on 2020-08-31 (events=split, no yfinance involved):

date close adjclose
2020-08-28 124.81 120.96
2020-08-31 129.04 125.06

The 28 Aug close is 124.81, not the ~499 the stock actually printed that day, so Close is already split-adjusted. The gap between the two columns (120.96 / 124.81 = 0.969) is the dividend factor alone. And utils.auto_adjust() just scales Open/High/Low by Adj Close / Close and renames Adj Close to Close, which is why the default output is adjusted for both.

Suggested wording for the second sentence: "Pass auto_adjust=False to get Yahoo's split-adjusted OHLC together with an Adj Close column that also includes dividends." That also answers the original confusion in #860 (people comparing Close from the two modes and wondering why only dividends differ).

@TTNAN

TTNAN commented Oct 11, 2026

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@arhancanli good catch — you're right, and thanks for the AAPL split evidence. Fixed in the latest commit: the note now says auto_adjust=False gives Yahoo's split-adjusted OHLC plus an Adj Close column that also includes dividends.

@ValueRaider

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Not in readme, that needs to be absolutely minimal. Move your prose into the Sphinx and readme can link to it.

@TTNAN

TTNAN commented Oct 11, 2026

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Done — moved the prose to a new Sphinx page doc/source/advanced/price_adjustment.rst (added to the Advanced toctree), and the README now just has a one-line note linking to it.

@ValueRaider

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@TTNAN
TTNAN force-pushed the docs/adj-close-note-860 branch from fb1343c to 722dcc3 Compare October 13, 2026 01:03
@TTNAN

TTNAN commented Oct 13, 2026

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Done — squashed to a single commit.

@ValueRaider

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I've made it absolute minimum

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Close/Adj Close in yf.Ticker vs yf.download

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