(MONEY Magazine) – In April, we nominated $20 billion Columbia/HCA (COL; NYSE, $33.50; 0.2% yield) as our Stock of the Month. But neither we nor the analysts we interviewed foresaw the mess the hospital management company was about to land in. We now think you should sell.

On March 19, agents from the FBI, IRS and Department of Health and Human Services arrived at the company's El Paso facilities. They weren't coming for treatment. According to an article in the New York Times, they may have been investigating whether Columbia inflated its billing of Medicare patients. A spokesman for Columbia told Money: "We are cooperating with federal agents, but we have not learned what the specific allegations are."

Some analysts are standing by the company. Says A.J. Rice of Bear Stearns: "This is a chance to buy a great company at a cheap price." If you have strong nerves and some insight about Columbia that gives you confidence that it will ride out this episode, you may want to hang on.

But if you bought shares solely on the strength of analysts' recommendations, you should consider getting out now. "Clearly, this stock is going to be volatile in the near future," says Peter Costa, a Boston-based analyst for ABN AMRO Chicago. In any event, the publicity cannot help the organization establish itself as a brand name in quality health care. --Duff McDonald