Hi joost,
  I now want to merge a new dataset which contains only CUSIP and Ticker. Could you please inform how to merge this dataset with COMPUSTAT or with CRSP. Is it likely that a firm has multiple tickers? Or some other difficulties that I will encounter in merging？
Best,
Xinjiao

hi Xinjiao,

Cusip is more ‘permanent’ than the ticker symbol, so Cusip is probably best. Do you know if it is ‘current’ (header) cusip, or if it is historic cusip?

Header cusip is in Compustat Funda, historic cusip is in CRSP dsenames.

best,

Joost

Hi Joost:

This post got me thinking: Are you aware of an overview that clarifies whether CUSIPs are history or current in the various WRDS datasets? Often it is not explicit whether CUSIPs are historic. For instance, Riskmetrics Directors and Riskmetrics Governance seem to use historic CUSIPs (meaning looking back in a panel, CUSIPs change). Also, I was under the impression that CUSIPs in other datasets such as Compustat are also historic (meaning looking back in a panel, CUSIPs change). I apologize if I cannot name the underlying tables in WRDS as I’m using Stata and only get data via the webinterface.

Thanks in advance!
Steve

hi Steve,

I believe the Cusip in Compustat is header (current value only). The best way to find out and know for sure is to count unique values by firm id.

Best regards,

Joost

Hi Joost:

Thanks for replying: I checked, and the CUSIPs in Compustat are indeed header (current). For Riskmetrics (now called ISS) Directors DB and Riskmetrics (now called ISS) Governance, I contacted WRDS to clarify. Here is the response:

In the legacy file, CUSIP shows the most recent CUSIP available at the cut off date.
In the new version, CUSIP is historical.

Best,
Steve

hi Steve,

Thanks for following up!

Best,

Joost