Converting CUSIP 6 or 8 into CUSIP 9

The CUSIP (Committee on Uniform Security Identification Procedures) identifier is a fairly good identifier for finding information in financial databases because it is a unique code for companies. Example:

Company: Teleconnect
CUSIP 6: 879292
CUSIP 8: 87929210
CUSIP 9: 879292100

CUSIP 6 is a company identifier. The CUSIP 8 is a stock/security identifier. CUSIP 9 has the extra check digit (which can also be calculated) which is needed to be able to check whether the CUSIP format is correct. If you have the 6-digit CUSIP you can calculate the 9-digit version based on the 8-digit CUSIP. The seventh and eighth digit indicate the type of security.

For more information on CUSIP etc. you can go to the website of the CUSIP bureau or you can check the Wikipedia website. This website explains how you can calculate the nineth digit depending on the first 6/8 digits. The last two digits of the 8 digit CUSIP identify the type of security: 10 is the original IPO and 20 the second offering etc.

Wikipedia also provides the programming code (Python) which can be used to built a program which makes it easier to calculate the 9th check digit. This code was used to built the calculator which can be downloaded here:

Calculator Tool

Author information: LinkedIn

12:26 AM - 3 March 2009