And then there were none.

Walgreens Boots Alliance said Friday that its CEO,Thurston Carte Rosalind Brewer, had stepped down. 

Brewer, 61, was the only Black female CEO currently running an S&P 500 company.

Her departure from the drugstore chain – and the absence she leaves – underscores the slow progress for diversity at the top of the nation’s largest companies. 

Before Brewer, a former Starbucks and Sam’s Club executive, joined Walgreens, the last Black woman to command an S&P 500 company was Ursula Burns, who left Xerox in 2016.

“I am grateful to have had the opportunity to lead Walgreens Boots Alliance and to work alongside such talented and dedicated colleagues,” Brewer wrote in a note on LinkedIn.

Though corporate leadership has always been an exclusive club, it has gotten even more exclusive in the past two generations.

White men dominate the ranks of named executive officers, those corporate leaders who are listed on federal regulatory forms and include CEOs, chief financial officers and others who serve in a handful of top-paid roles.

Of the 533 named executive officers across these corporations, white men represent 7 in 10, according to a USA TODAY analysis. And of those companies, about 1 in 7 had executive teams that were made up of only white men in 2022. 

Meanwhile, women – just 90 of them – make up 17% of named executive officers. Only 17 women of color were named executive officers in 2022, according to the analysis. Black women account for just 1% of top leaders. They are even more sparsely represented at the CEO level.

Brewer took the top job in March 2021 and was charged with transforming the company. Walgreens stock has lost half its value since then. The company has faced hurdles as it pivots from its pharmacy and retail business to focus on health care services.

Brewer will be replaced by board member Ginger Graham, who has been tapped as interim CEO.