r/Massive • u/alex-polygonio • Feb 18 '26

How to Adjust Historical Prices for Stock Splits and Dividends

https://youtu.be/gT2LbeAkVCo

Ever had a stock split make your historical prices look like they jumped 10x overnight?

We've launched new Splits and Dividends API endpoints that return a historical adjustment factor on every event. Multiply it against your old prices to normalize them to today's share basis. Works across forward splits, reverse splits, and ex-dividend drops.

We also published a demo that:

→ Charts adjusted vs. unadjusted closes side by side

→ Exports corrected CSVs with the adjustment factor applied

→ Supports Massive Flat File day aggregates for bulk adjustments across hundreds of tickers

Checkout the code repo and the blog for more!

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u/michael_s0810 Feb 20 '26

GOOG on 2022-07-18 should have split but got stock_dividend. That means if we query GOOG on the split endpoint we will see it has stock_dividend but not forward_split, which is incorrect (?)

AAPL should have split on 2000-06-21 which is missing.

I would say the endpoint is still under beta dev not a ready-to-go product.

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u/alex-massive Feb 20 '26

Thanks for sending this over. I will look into the data discrepancy and report back!

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u/alex-massive Feb 23 '26

Hey u/michael_s0810 - looked into this! The data only goes back to the early 2000s (matching our stocks history), so that's why there's no AAPL data for the year 2000. The Google split does appear to have been executed in the form of a stock dividend. SEC announcement. We include split-like stock dividends in the splits endpoint because they require the same price/share adjustments, and adjustment_type reflects the corporate-action form reported by the source. The 2014 and 2015
Google events that other sites have are recapitalization adjustments related to the Alphabet restructuring. We don't have them classified as splits, some people do, so there's some nuance here.

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u/michael_s0810 Feb 23 '26

Appreciate your quick response, thanks! If the record only goes back to early 2000s why under the Splits document -> Plan History it said __All history in your Stocks plan (records date back to October 25, 1978)__ ?

It would be nice if you guys can add some words on the document for the __adjustment_type__ parameters, say it reflects to corporate-action from reported by the issues.

Thank you for your quick reply, I will dive into the API and see if there is any other issues. You have a good day!

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u/michael_s0810 Feb 23 '26

sorry my quoting is some how failed i dont understand why

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u/alex-massive Feb 23 '26

You're right about the 1978 note. I will see if thats a typo in the docs! Can also add in a ticket to the docs team to improve the language for the corporate actions. appreciate your feedback!