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