One owns a for-profit insurer, a venture capital company, and for-profit hospitals in Italy and Kazakhstan; it has just acquired its fourth for-profit hospital in Ireland. Another owns one of the largest for-profit hospitals in London, is partnering to build a massive training facility for a professional basketball team, and has launched and financed 80 for-profit start-ups. Another partners with a wellness spa where rooms cost $4,000 a night and co-invests with "leading private equity firms."

Do these sound like charities?

These diversified businesses are, in fact, some of the country's largest nonprofit hospital systems. And they have somehow managed to keep myriad for-profit enterprises under their nonprofit umbrella — a status that means they pay little or no taxes, float bonds at preferred rates, and gain numerous other financial advantages.