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ISIN Codes Are Case Insensitive

Article Quant Q&A · Author: ngx472
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Summary

The document answers a practical securities-data question: whether letter case matters when handling International Securities Identification Numbers. It states that ISINs are twelve-character alphanumeric identifiers, with letters drawn from A through Z and digits from zero through nine, and concludes that the codes are not case sensitive. This matters when normalizing or comparing identifier input, since changing letter case should not change the identity represented by an ISIN.

The answer attributes the character specification to ISO 6166 and its annex on allowed alphabetic characters. The document offers no implementation procedure, examples of data-cleaning rules, or discussion of other identifier systems; the comparison to RIC codes appears only in the question. Its scope is therefore narrow: it records the stated standard for ISIN characters and the resulting case-handling conclusion, rather than providing broader security-master guidance.

Key ideas

  • ISINs use twelve alphanumeric characters.
  • The allowed letters are specified as uppercase A through Z, alongside digits zero through nine.
  • The document states that ISINs are not case sensitive.
  • It attributes the character rules to ISO 6166.

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Full text
# Are ISIN case sensitive?


# Are ISIN case sensitive?












Are ISIN codes case sensitive like RIC Codes are? We need to know this in order to sanitize input. This completely describes my problem!

## Answer by Richard at NorgateData (score 4)

https://quant.stackexchange.com/a/37123

ISINs are a 12 character alphanumeric code where the letters allowed are A-Z and the digits are 0-9.

They are not case sensitive.

This is defined in the ISO 6166 standard and the alphabetic characters allowed are given in Annex A of the standard - that is, only A through Z (uppercase) are specified.

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