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Winner's Curse in Acquisitions (Academic Paper) (view source)
Revision as of 19:19, 15 November 2016
, 19:19, 15 November 2016→Governance_Final Table (Amir)
Merging with CRSP:
Q) Is CUSIP in RiskMetrics current or historical? How can I use it to merge with CRSP?
A) The Legacy files have the current CUSIP. With each update, WRDS updated the historical data with the latest value. Starting with the new Director and Governance files, we no longer modify the historical data.
To merge any of these datasets with CRSP, you can join on the NCUSIP field. This will match a single Permco (company identifier), but you may still need to select the primary Permno because some companies issue more than 1 security.
Merging EXECUCOMP AND IRRC:
Q) What is the best way to merge Execucomp and IRRC (director and governance) databases? I understand they both have CUSIP, but that matching with CUSIPs isn't always ideal since the CUSIP can change over time for the same firm. A) All Execucomp (CUSIP), IRRC Governance (CN6), and IRRC Directors (CUSIP) CUSIPs are header cusips, in that they reflect the most recent CUSIP that the company has had. There are however 2 main differences between Execucomp's CUSIP and IRRC's CUSIP and CN6:
1. While Execucomp uses 8-digit CUSIP, both IRRC datasets have 6-digit CUSIPs. Therefore, you need to use a SAS function like "substr" to take the first 6-digit of Execucomp CUSIP before merging it to IRRC data. ex: cusip6 = substr(CUSIP,1,6);
2. While header convention reflect "most recent" value of an identifier variables, it is dependent on the date of update of each dataset. Therefore, for CUSIPs that change in between the time that both databases are updated, you might find some discrepancy. To overcome this issue, we recommend that you make use of the CRSP name files (ex: stocknames), that contains all historical CUSIPs that a company has had.
