CUSIP is a 9 character long identifier. The last digit is a check sum checking the first 8 previous characters. This seems to me that it is not possible for two securities to have the same 8 characters and different check sum. I know this is not exactly quantitative, but I haven't found a forum where I could ask.

Source: https://www.cusip.com/cusip/index.htm

  • 2
    $\begingroup$ No, for exactly the reasons you state, two CUSIPs cannot differ in inly the last digit. The last digit is a function of the first 8 digits, and any ordered set of 8 digits has only one proper checksum. If two CUSIPs are the same except for rhe last digit, one of them is not a CUSIP, and in fact making that determination is the very purpose of the checksum digit $\endgroup$ – Dan Bron Nov 21 '14 at 12:16

No, 9th character is computed using deterministic algorithm described here: http://en.wikipedia.org/wiki/CUSIP#Check_digit_pseudocode.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.