Date Added: Dec 2009
The authors' data are taken from Compustat and consists of annual data from 1971 to 2006. In the main text, they only report results based on data starting in 1980, but in Appendices B and C they show that the results are robust to including the earlier part of the data set. Compustat includes firms listed on the three US exchanges, NYSE, AMEX, and NASDAQ, with a non-foreign incorporation code. They exclude financial firms (SIC codes 6000-6999), utilities (SIC codes 4900-4949), and firms involved in major mergers (Compustat footnote code AB) from the whole sample.