Why are U.S. corporate boards under-diversified?

Research tells us that firms with diverse workforces generally outperform those that do not. And in recent years, corporate America has taken significant strides towards greater heterogeneity in the employee base. But a problem remains at the top.

U.S. boardrooms remain overwhelmingly Anglo Saxon and male. No less than 81 percent of the Standard & Poor (S&P) 1500 Index directors in America today are white men. White women account for 11 percent, while ethnic minority men make up 6 percent. Meanwhile, female minority board members account for just 2 percent of the total. For businesses, this is becoming problematic, not least because institutional investors and regulators like the Securities and Exchange Commission have started asking firms to open up about their processes in selecting board members. Where diversity is a criterion, firms are required to be transparent about specifications and frameworks.

All this scrutiny begs the questions: What is going on in the American boardroom? And why is there still such a stark lack of diversity in the upper echelons of business in the U.S. today?

Grace Pownall, professor of accounting
Grace Pownall, professor of accounting

Shedding light on this issue is new research from Grace Pownall, professor of accounting, and Justin Short, assistant professor of accounting, at Emory University’s Goizueta Business School. Together with Zawadi Lemayian of Washington University, they parsed 12 years of data on gender, ethnicity, and salaries from the S&P 1500 to build a composite picture of who’s who and who’s paid what in U.S. boardrooms. What they found points to a systemic shortage of female and minority executives making it onto shortlists for board appointments. But that’s not all. Once women and minority men do make it onto the board, there’s another roadblock waiting for them: they are not getting promoted at the same rate as their white, male counterparts.

There seem to be two complex dynamics at play, said Short: a glass ceiling effect hampering the upward trajectory of Black, female, and other minority executives, and what he and his co-authors call “myopic” bias on the part of corporate America.

Justin Short, assistant professor of accounting
Justin Short, assistant professor of accounting

“We developed two hypotheses that might explain what’s behind the lack of diversity on boards,” explained Short. “The glass ceiling hypothesis comes from what we see as a shortfall of women and ethnic minorities in the workforce relative to white men—so the theory here is that these groups just aren’t getting promoted to the point where they would be considered for board positions.”

“The alternative hypothesis we worked on was that there might actually be a plentiful supply, but that companies just don’t see directors from different backgrounds as being as valuable in the same way,” he said. “And we would put this down to some kind of institutional myopia or bias at the very highest echelons of business.”

To put these hypotheses to the test, Short and his colleagues first collected demographical data on American board members from a database compiled by Institutional Shareholders Services. Here they were able to determine the gender and ethnicity of individuals. They also ran a simple statistical regression on salaries using data from S&P. Then they compared the two.

“Economic theory tells us that if there’s a high demand for diverse directors—women and ethnic minorities—and there’s a low supply of them, then these directors will be able to command higher salaries than others,” said Short. “It’s a simple case of supply and demand, and minorities will come at a greater premium.”

Looking at the S&P 1500 data, they found that female and minority directors were indeed getting paid more on average than white male counterparts in other companies. And when they analyzed this more closely, Short and his co-authors found that these salaries were in general being paid by larger, more successful firms.

“We can see that women and minorities are commanding higher compensation than the average white male director across the S&P universe of 1500 companies, and it’s the bigger, better paying firms that are hiring them,” Short said. “So that tells us that the top companies are proactively trying to build diversity in their boardrooms. At the same time, it shows there is a deficit of supply in this talent pool—the so-called glass ceiling dynamic.”

To understand whether bias or institutional myopia might also be limiting the prospects of Black, female, and ethnic directors, Short et al. also looked at differences in compensation within the same company, and here they found something striking. While they made more on average than the typical white male director in U.S. firms, minority directors were being paid around 3 percent less than their direct counterparts – the white male directors on the same board.

“This tells us something important,” said Short. “Once these directors make it to the board, for most of them that’s it. They don’t advance or achieve promotion at the same rate.”

This could be due to bias or what Short calls a Rolodex effect: “Maybe it’s because they didn’t go to the same school as the chairman of the board, or weren’t connected socially in the same way, so they don’t appear in the Rolodex of candidates with right or familiar credentials to get promoted within the board,” he said. “We know it’s not about hard skills or aptitudes because the data shows us that women and minority directors typically hold more qualifications than their counterparts. But for whatever reason, once they are on the board, they fail to advance in the same way as white men.”

Interestingly, Short and his colleagues found that there was a very small number of women and minority directors sitting on the boards of multiple companies in the U.S.

“Pulling it all together, we see that there’s a generalized shortage of women and ethnic group candidates in the U.S.,” Short said. “Successful companies are proactively on the lookout for them and offer higher compensation to attract them.

“But there seems to be a glass ceiling effect acting as a bottle neck for talent. We also see that minority directors become a bit stuck once they’re on a board. The upward momentum tails off relative to their white, male colleagues. This could be due to bias or myopic thinking.”

All of this should provide rich food for thought for the most senior decision-makers in U.S. enterprises, according to Short and his co-authors.

With the pressure on to drive board-level diversity in corporate American, leaders need to be cognizant of the roadblocks or cut-off points to tie to ethnicity and gender.

Diversity is something we urgently need to enable and nurture in the United States. Without diversity, creativity and innovation can stall, and in business you run the risk of deferring to group think—sourcing ideas and perspectives from the same small pool of shared experience or expertise,” said Short.

“It’s encouraging to see that diversity has increased over time and the largest companies are proactive. But there are still vast gaps of representation on the board compared to the workforce. There’s still work to be done because diversity in American business should be commonplace.”