Xerox CEO Ursula Burns’ plans to step down from her post has sparked a new conversation about diversity in the upper echelons of business. After Burns abdicates her position, there will no longer be any S&P 500 company with a black woman as CEO.

Burns, who became CEO of Xerox in 2009, is the first black woman CEO to run a Fortune 500 company. She joined the business services giant in 1980, as an intern. She served as president before being promoted to chief executive officer. According to a statement released by Xerox, Burns will chair a new document technology company, which was formed at the Xerox split into two. New CEO’s will be appointed for both companies.

Burns is currently one of only 20 women who run Fortune 500 companies, accounting for 4% of all CEO’s. She is also one of only 5 black CEO’s. According to Fortune, only 15 black CEO’s have run Fortune 500 companies, ever.