Jack Stoddard, a longtime health care executive, has been named as chief operating officer of the new health venture being launched by Amazon.com Inc., JPMorgan Chase & Co. and Berkshire Hathaway Inc. Stoddard started Tuesday, according to a statement from the still-nameless health venture. He’ll work with Atul Gawande, the Harvard surgeon and writer who was named in June to run the initiative. The leaders of the three companies have warned it will take time for the effort to meet its goal of improving care for their workers. (Zachary Tracer, Bloomberg News)