In his Aug. 9 letter to UnitedHealth, the labor federation's secretary treasurer, Richard Trumka, wrote: "The timing of stock option grants during the post-9/11 period of depressed stock prices raises the issue of whether executives took advantage of a national tragedy to compensate themselves . . . Lastly, any unusual timing of post 9/11 stock option grants could be an indication that they were inappropriately backdated."

At UnitedHealth, the directors are also under scrutiny for the equity compensation they received. On Aug. 10, Bloomberg News reported that the health insurer's 10 non-executive directors held $230 million in stock as of late March, when the company filed its proxy statement. Those directors also held more than 3.1 million stock options with an underlying value of $175 million.

"You have to ask yourself, are these people paying attention to the mission of the corporation, or are they being distracted by the amount they're getting themselves?" Minnesota Attorney General Mike Hatch told Bloomberg News.

Overall, more than 108 companies have disclosed internal or regulatory probes into their stock option practices. Among the latest firms to announce internal probes are Keithley Instruments, an Ohio company that makes testing equipment for semiconductors, and BEA Systems, a California software firm.

In the past two weeks, PMC Sierra, a maker of semiconductors; J2 Global Communications, which makes communications software; electronics manufacturer Sanmina-SCI; and Boston Communications have delayed filing their quarterly financial results. With late filings, some firms have fallen out of compliance with Nasdaq Stock Market listing requirements. After receiving delisting notices this week, Apple Computer, Juniper Networks, Rambus, Qwest Software, and Monster Worldwide said they would seek hearings before Nasdaq's listing panel. Rambus, a computer chip designer, also announced that ex-CEO Geoff Tate, who had served as the sole member of the company's stock option committee, had resigned from the company's board.

In addition, software maker McAfee said it would restate three years of earnings, while Amkor Technology, a packager of semiconductors, said it would restate more than eight years of results, according to news reports. Earlier, 14 executive officers at Molex, an Illinois-based supplier of electronic connectors, agreed to reimburse the company $685,000 for gains they received from misdated stock options, according to ElectronicsWeekly.com.