The investigations came to light after a series of probing stories in the Wall Street Journal in May 2006, discussing apparent backdating of hundreds of millions of dollars' worth of stock options by UHC management.
The backdating apparently occurred with the knowledge and approval of the directors, according to the Journal.
In December 2005, the company received final regulatory approval for its $9.2 billion purchase of Pacifi Care Health Systems.
It agreed to divest parts of Pacifi Care's commercial health insurance business in Tucson, Arizona and Boulder, Colorado to satisfy antitrust regulator concerns, and also agreed to end its network access agreement with Blue Shield of California.
Legal actions filed by the SEC against United Health Group itself are still pending.