Uber's head of global operations resigns

Uber's head of global operations is the latest executive to step down at the troubled ride-hailing company.

Ryan Graves told staff in an email Thursday that he will transition out of his role as senior vice-president of global operations in mid-September. Graves will remain on Uber's board.

Graves was Uber's first hire a little more than seven years ago. He also served as the San Francisco-based company's first CEO, in 2010.

Graves thanked staff and former Uber CEO Travis Kalanick. Kalanick resigned under pressure in June after a months-long investigation into sexual harassment and other behaviour problems at the company. Uber has fired at least 20 employees as a result of that investigation.

Graves said he will support Uber's new CEO once that person is hired.