A CUSIP number is a 9-character alphanumeric security identifiers that they distribute for all North American securities for the purposes of facilitating clearing and settlement of trades. en.wikipedia.org/wiki/CUSIP -- This post was edited to remove a commercial link. Read our discussion policies for more Community best practices.

CUSIP numbers are unique numbers for each stock or security that identifies them when purchased or sold. Because the numbers are unique, a sale or purchase can be tracked over time. Each 'trade' will have a separate CUSIP number even if it is the same stock. For instance, if I purchase 100 shares of XYZ stock today, it will have its own CUSIP number. If I then purchase another 100 shares of XYZ stock next week, it will have a different CUSIP number because it was a different transaction.

BizResearcher, that was an interesting explanation on how the cusip number function in stock transactions. It brings other questions to mind, which I will initiate in separate threads. Thank you.