Wright et al (1995)
Wright, Peter, Stephen P. Ferris, Janine S. Hiller, and Mark Kroll, "Competitiveness Through Management of Diversity: Effects on Stock Price Valuation." Academy of Management Journal, 38(1), 1995.
From the authors' abstract: "Using data from 1986 through 1992, we examined the impact that announcements of U.S. Department of Labor awards for exemplary affirmative action programs had upon the stock returns of winning corporations and the effect that announcements of damage awards from the settlement of discrimination lawsuits had on the stock returns of corporations. The results suggest that announcements of awards may be associated with competitive advantage and that discrimination-related announcements may be associated with inability to achieve such advantage."