Using Missing Stock Prices to Identify Exchange Holidays

Summary

The document investigates why AAPL and IBM have no prices for a particular historical date and how to research similar anomalies. The answer explains that U.S. exchanges were closed for Good Friday, a holiday whose date moves from year to year. It recommends treating missing observations across multiple major stocks as a clue that the market may have been closed rather than assuming that each security has an individual data problem.

The response suggests checking whether a broad index such as the S&P 500 is also missing on the date. That pattern can help distinguish a market-wide holiday from an isolated gap in a security’s history. The example is a practical heuristic, not a complete data-quality procedure: missing index or stock observations can have other causes, and holiday calendars or another authoritative trading calendar should be used to confirm the explanation.

Key ideas

• A missing price across several major stocks on the same date may indicate an exchange holiday.
• Good Friday falls on a different date from year to year and can explain a market-wide gap.
• Checking whether a broad index is also missing can help identify a market-wide closure.
• The missing-data pattern is a clue and should be confirmed against a trading calendar.

Tags

# Why are there missing prices for 1981-04-17?


# Why are there missing prices for 1981-04-17?












I was going over historical prices in Yahoo Finance, when I noticed that AAPL and IBM have no prices for 1981-04-17. I have a couple of questions regarding this:

- Why are the prices missing?

- In the future, how can I answer such historical anomaly questions? Searching the date and "finance" or "market" in Google didn't give anything interesting.

Thanks.

## Answer by nbbo2 (score 3, accepted)

https://quant.stackexchange.com/a/70747

According to the following link the stock exchanges were closed on 1981/04/17 due to Good Friday, a major Christian holiday whose date varies from year to year but is generally in March or April.

http://nyseholidays.blogspot.com/2012/11/nyse-holidays-from-1981-1990.html

In general if 2 major stocks are missing (or even better if the SP500 index ^SPX is missing) on a given day you should suspect a holiday.

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