Haven, the Amazon-Berkshire-JPMorgan health care company, has already lost its No. 2 executive

New York(CNN Business) The No. 2 executive at Haven, the health care company backed by Amazon, JPMorgan and Berkshire Hathaway, has left nine months after joining the fledgling firm.

Chief Operating Officer Jack Stoddard departed April 30 for personal reasons, a Haven spokesperson confirmed. The company hasn't named his replacement.

"Jack played an important role in the early stages of Haven, but we understand his decision to leave the company for family reasons," a spokesperson told CNN Business. "We want to thank him for all of his contributions."

Stoddard joined Haven in September 2018 from Comcast, according to his LinkedIn. Prior to that, he held various roles at other healthcare companies, including UnitedHealth (UNH) Group.

The Boston-based non-profit venture was formed in January 2018 by Jeff Bezos, Warren Buffett and Jamie Dimon. It is led by Dr. Atul Gawande, a renowned surgeon and New Yorker writer, who was named CEO in June 2018.

Haven aims to make primary care easier to access, insurance benefits simpler to understand and use and prescription drugs more affordable, the website says. It seeks to harness data and technology to make the overall health care system better.

One main goal is to give the three companies' combined 1.2 million employees and dependents better health care choices and bring down prices. Ultimately, the high-profile venture's work is intended to serve a wider audience.

There is enormous pressure on Haven to produce innovative ways to tackle the nation's longstanding problem of high health care costs, though it has been given time to develop solutions. Gawande and the venture's mega-rich leaders, who are known as disrupters, have released little information about the effort.

--CNN Business' Tami Luhby contributed to this report