“After nearly two years with Founders Fund, Kevin is ready for a new challenge. He remains a friend of the firm and we’re excited to see what he does next,” said a Founders Fund spokesperson.

Hartz joined Founders Fund in September 2016 and transitioned into an entrepreneur-in-residence and venture partner role in February. Fortune has learned that Hartz will leave to pursue other ventures, likely as an operator. He’s a serial entrepreneur, founding three companies — Eventbrite, ConnectGroup, and Xoom Corp. He was also an angel investor in companies including Airbnb, PayPal, Pinterest, Trulia, Thumbtack, and Uber.

Fortune also learned that Hartz will continue working as an advisor for Eventbrite, which he co-founded with his wife Julia Hartz, who serves as the CEO. He’ll also keep his board seats at the two stealth companies he invested in while he was at Founders Fund.