Amazon has disrupted fashion, books, furniture, food, cloud-based storage services, and much else besides. Now, it’s coming for one of the biggest, most complex industries in the US: healthcare. Today (Jan. 30), Amazon, Berkshire Hathaway, and JPMorgan announced a vague but market-moving plan to launch an independent company that will offer healthcare services to the companies’ employees at a lower cost. The venture, which will be managed by executives from the firms, will be run more like a non-profit, than a for-profit entity. The market value of 10 large, listed health insurance and pharmacy stocks 1 dropped by a combined...