The Verisign board has decided to restate more than four years worth of financial reports after an internal review found stock options may have made them unreliable.

The investigation by the online transaction security firm's independent directors is ongoing. "Incorrect measurement dates and other administrative inconsistencies" already uncovered precipitated the action, announced on Tuesday.

The SEC has its own investigation into Verisign, along with dozens of other technology firms over the practice of backdating share options. Backdating involves retroactively setting the date they were granted to improve their value - itself not illegal at the time in question - but the effect non-disclosure may have had on some firms' accounts submissions was.

Verisign says its findings to date indicate $250m in options needs to be included in accounts from 2001 to 2005, and the first quarter of 2006. The internal review should be complete by the end of the year. Cleaned up accounts will be made available as soon as possible after that, Verisign added.

Former Brocade CEO Greg Reyes joined the Verisign board in 2002. The first high profile Silicon Valley figure to face criminal charges in the SEC backdating investigation, Reyes resigned from Verisign two weeks after the SEC announced it would indict him. The SEC alleges he used backdating to mislead Brocade investors.

Verisign's shares lost more than 15 per cent of their value around the time the charges were filed against Reyes, but have since recovered. ®