According to a document filed with the Securities and Exchange Commission on Friday, Twitter co-founder Evan Williams is leaving the company's board.
Williams said in the filing, "It's been an incredible 13 years, and I'm proud of what Twitter has accomplished during my time with the company.
"I will continue rooting for the team as I focus my time on other projects."
Williams throttled back his role in the San Francisco-based startup eight years ago, turning his attention to new endeavours including creating popular online publishing platform Medium.
Williams also thanked Twitter's nearly 4,000 employees and said he would continue to "root for the team."