From taking tighter control over the health insurance market themselves to pushing decisions and costs down to individuals, businesses are experimenting with a host of new ways to offer health-care coverage, spurred in part by the launch of the Affordable Care Act, but also by the inexorable rise in the cost of medical care in the United States. The moves promise to change a social compact that has existed between employers and employees over health-care coverage for more than a half century. Already, for instance, several large corporations have announced they are setting up private exchanges like the one the fictitious tool-and-die maker belongs to.