Afra Afsharipour, the senior associate dean for academic affairs at University of California, Davis School of Law, brushed up against the lack of diversity in M&A work in her seven years as a young lawyer at Davis Polk & Wardwell. "I was often the only person that was like me in the room," the first-generation immigrant says. 

But even if this structural imbalance in M&A is obvious, it hasn't been subjected to a rigorous empirical evaluation, unlike the gender gap in law firms or the question of women in the C-suite or on corporate boards.