The largest private-equity owners of HCA Holdings have filed papers to bring to market 50 million of the shares they hold. If they unload them all — and there's no reason to think they won't given their past sales — Bain Capital, Kohlberg Kravis Roberts and members of the Frist Family will combined trim their stake in HCA to 39 percent from almost 51 percent. That means the HCA board of directors will need to begin bringing in new blood because it will no longer be a "controlled company" under stock exchange rules. Check out the company's prospectus here.