backdated at least 19 option grants and should have taken a charge of about $21 million to reflect their cost, the company said late Monday.
The discrepancies were found during a voluntary review by the hard-drive maker's independent directors.
The special committee found "no evidence that anyone manipulated the grant documentation or grant dates in order to avoid compensation expense or other financial statement impacts," the company said in a statement.
Western Digital said it does not expect the investigation to result in a material adjustment to fiscal 2005 and 2006 operating results included in its earnings release on July 27.
Shares of the company closed the regular session down 44 cents to $17.17.