Investors rally and stocks jump when companies hire Black leaders, according to the results of a study published in Strategic Management Journal.

In the study of CEO appointments in median-sized firms from 2001 to 2020, markets reacted positively to the appointment of Black CEOs “with an average abnormal return of +3.1% (or +2.0% after conservatively addressing outliers).” By comparison, firms that appointed White CEOs saw their market capitalization decline 0.91% over the same period.

Black Americans make up more than 12% of the country’s population, the Wall Street Journal reported, citing 2021 data from the Bureau of Labor Statistics, but make up less than 6% of the country’s chief executives.

A possible explanation, according to the researchers, is that racial biases and stereotypes tend to slow Black employees’ ascent through the ranks. By the time Black leaders reach the level of CEO, they often have more years of education, advanced degrees and elite education than their White counterparts.  

“What we actually found was, almost because of the bias that they’ve experienced, there’s evidence that there is a significantly higher bar for advancement for Black CEOs compared to white CEOs,” Ann Murphy, PhD, associate professor at Stevens Institute of Technology and study co-author, told Fortune.

“By the time a [Black executive] gets to the CEO office, they’ve time after time had to prove themselves, … So, when they reach that highest point, they are extraordinary,” she added.

The study contradicts the findings of a 2021 study published in Strategic Management Journal that indicated that investors reacted negatively to the appointment of Black CEOs and positively to the appointment of white CEOs.

“Given these possible implications, we undertook a study to understand why the reactions to Black CEO appointments were so negative,” wrote the authors of the more recent study. “Contrary to their reported results, we find that investors do not appear to be biased against newly appointed Black CEOs.”

Murphy told Fortune that the research data behind the previous study of Black leaders was not made public, and the study she participated in was peer-reviewed.

“Care must be taken when interpreting our findings. First, we are not suggesting a causal relationship. Firms cannot expect a positive reaction to the appointment of any Black CEO. Rather, our results are likely driven by the fact that Black individuals appointed to be CEO are exceptional,” the authors of the current study wrote.