Shares of UnitedHealth Group (UNH -5.75%) plummeted again on Wednesday. The company's stock is down 5.8% as of market close, while the S&P 500 (^GSPC -1.61%) and the Nasdaq Composite (^IXIC -1.41%) lost 1.6% and 1.4%, respectively.

The troubled health insurance giant is facing a new damaging report claiming it made secret payments to nursing homes in order to cut costs.

UnitedHealth allegedly paid nursing homes to reduce hospital stays

The Guardian is reporting that UnitedHealth made secret bonus payments to nursing homes to help keep ailing residents out of hospitals. The investigative report claims that the company also staffs nursing homes with its own medical teams, and in at least several cases, residents who needed immediate hospital care did not receive it after UnitedHealth staffers intervened.

The incidents are part of a larger program in which the insurer has inserted itself into the day-to-day operations of nearly 2,000 nursing homes around the nation. One former UnitedHealth executive involved with the program told The Guardian, "You gain profitability by denying care, and when profitability suffers for the shareholders, that's when people get crazy and do things that are not appropriate."

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One more report

UnitedHealth Group is currently under investigation by the DOJ for fraudulent billing practices, so this is just the latest in a string of reports of actions by the company that range from generally dubious to outright criminal.

There are just too many issues facing UnitedHealth, and this once seemingly stable investment looks far from it at the moment. I would stay away from UnitedHealth stock.