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*Private Data: Capital IQ data, Dealogic data, SDC VentureXpert, and compilations of news stories to identify private equity investments transactions, their characteristics, and the nature of their exits . 472 LBO transactions between jan 1980 and december 2005. Used Harvard business school patent database, which contains U.S. patent and trademark office electronic records through may 2007. HBS patent database was researched and cleaned up version of USPTO database. Final sample consists of 6398 patents from 472 firms granted from 1984 through may 2007. Variables: *secondary exit - an LBO backed firm subsequently sold to another private equity fund*IPO - an lbo backed firm subsequently going public*trade sale - an lbo backed firm sbusequently being acquired by a strategic buyer*bankruptcy - an lbo backed firm subsequently filing for bankruptcy *event year - indicator variables that equal one for the given year in event time (the base year is year 0)*post - an indicator variable that equals one for event years 1 and forward *post plus one - an indicator variable that equals one for event years 2 and forward *patent applications share of firm's preinvestment patents in class - the fraction of the firms' pretransaction patents that are in the same industry class*change in firm's patents in class - an indicator for whether the difference in the share of patents in the class between the pre- and posttransaction periods is positive*post x share - an interaction between post and awardsshare of firm's pre-investment patents in class*patent application date post x change - an interaction between post and grant datechange in firm's patents in class
→Lerner et al 2011
filename={Lerner et al (2011) - Private equity and long run investment the case of innovation}
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Finds that patents private equity backed firms applied for in the years after the investment are more frequently cited, showing no deterioration in patent orginality and generality. The leve level of patenting does not appear to consistently change, and the firms' patent portfolios become more focused in the years after the private equity investments. The areas where the firms concentrate their patenting after the private equity investment, and the historical strengths of the firm, tend to be the areas where the increase in patent impact is particularly great.
===Zahra 1995===
