White (2013)

White, Roger.  “Greed is Good: The Agency Costs of Blockholder Philanthropy.”  Working paper (Robinson College of Business, Georgia State University), June 27, 2013.

From the author's abstract:  "Recent experimental research in corporate social responsibility suggests that principal philanthropy offers benefits to the firm. I test this finding using archival data in a natural experiment. In publically traded firms, I find that charitable pledges by blockholders create agency problems that overwhelm any benefits and destroy shareholder value."

Link (2014 draft):  http://www.fmaconferences.org/Nashville/Papers/GreedIsGood.pdf