Doomsday investor Paul Singer and Athenahealth's Jonathan Bush

On May 18, 2017, Jonathan Bush was standing at the stern of his luxury catamaran, the Zenyatta, named for a champion Thoroughbred racehorse, when he received a text message from a colleague warning him not to answer calls from phone numbers he didn’t recognize. Bush, the co-founder and C.E.O. of the health-care technology company Athenahealth, had just finished a three-day race with his company’s sailing team, going from the Bahamas to Bermuda. Bush is the nephew of one former President, George H. W., and the cousin of another, George W., and his professional and personal lives were intertwined. He socialized with members of Athena’s staff as if they were college friends. (“We have a drinking team that has a sailing problem,” he said, half-jokingly, of the Bermuda group.) On social media, he documented nights spent partying with employees alongside his family visits to Kennebunkport and his kids’ soccer games. That day, as the Zenyatta sat in the Bermuda harbor, Bush’s phone rang. He answered it.