In brief: Uber this week announced that co-founder and former CEO Travis Kalanick will be stepping down from its board of directors on December 31, 2019. The company has not yet said who will fill the vacant board seat.

A spokesperson for the transportation company told CNBC that Kalanick has sold all of his Uber stock. According to the publication, his holdings are estimated to be worth around $2.5 billion.

Dara Khosrowshahi, Uber's active CEO, said very few entrepreneurs have built something as profound as Kalanick did with Uber, adding that he was enormously grateful for his vision and tenacity as well as his expertise as a board member.

Kalanick said that at the close of the decade, and with Uber now public, it seems like the right time to focus on his current business and philanthropic pursuits. "I'm proud of all that Uber has achieved, and I will continue to cheer for its future from the sidelines."

Kalanick stepped down as CEO in 2017 following a string of controversy and scandal involving the company he helped launch in 2009. He remained linked to the company through his board seat but now that he has relinquished that and sold off his last remaining stock, he has officially cut all remaining ties with Uber. His latest venture, Cloud Kitchens, rents out space to restaurants to prepare food for delivery.

Uber headquarters by Sundry Photography