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Winner's Curse in Acquisitions (Academic Paper) (view source)
Revision as of 18:15, 15 November 2016
, 18:15, 15 November 2016→Governance_Final Table (Amir)
Best Identifier to Use in RiskMetrics Directors- Changes to Identifier between Legacy and Current Files
1. The primary identifier in the current dataset is year-ticker-director_detail_id. Ticker is better populated than cusip in earlier years, but should be about the same in the latest years. For the legacy directors, director_detail_id was in use for some years and legacy_director_id for others.
2. Cusips in the legacy file are "header". With each update, WRDS modified all previous cusips for a company to match the latest. Although it may help in some cases, it may hurt in others and it is not quite the way the data was delivered. Starting with the new directors file, Cusips appear in the file as they were delivered (effectively making them historical going forward). Cusips in the legacy data were also uniformly truncated to 6 digits for consistency. The new file reports them as they are delivered, typically (but not always) 9 digits.
3. Tickers were not changed over time and appear as they were delivered. One example is legacy company id (legacy_pps_id) 25 has tickers ASN and IKN.
