Diversity is probably a competitive differentiator that shifts market share toward more diverse companies over time, McKinsey said.

McKinsey has been examining diversity in the workplace for several years. The Diversity Matters report examined proprietary data for 366 public companies including financial results and the composition of top management and boards in the U.S., Canada, Latin America, the U.K. Here are some other findings:

• Companies in the bottom quartile both for gender and for ethnicity and race are statistically less likely to achieve above-average financial returns than the average companies in the data set (that is, bottom-quartile companies are lagging rather than merely not leading).
• In the U.S., there is a linear relationship between racial and ethnic diversity and better financial performance: for every 10 percent increase in racial and ethnic diversity on the senior-executive team, earnings before interest and taxes rise 0.8 percent.
• Racial and ethnic diversity has a stronger impact on financial performance in the U.S. than gender diversity, perhaps because earlier efforts to increase women’s representation in the top levels of business have already yielded positive results.
• The unequal performance of companies in the same industry and the same country implies that diversity is a competitive differentiator shifting market share toward more diverse companies.

The case for greater diversity is becoming more compelling, McKinsey reported, but achieving diversity is not easy.

“Given the higher returns that diversity is expected to bring, we believe it is better to invest now, since winners will pull further ahead and laggards will fall further behind.”