Broadcom (BRCM) found more stock option irregularities and said it expects its restatement to amount to at least $1.5 billion.

The Irvine, Calif., wireless chip company said in July that its audit committee had found $750 million worth of restatements dating back to 2000. But on Friday, Broadcom said it found additional questionable grants and expects the restatement "will be at least twice the amount previously estimated and could be substantially more, depending upon the resolution of certain accounting issues."

Broadcom said the additional improper grants were made between 1998 and 2003, necessitating restatements of 1998 and 1999 financials. The company said its probe is ongoing but it can't say when it will be complete.

The

Securities and Exchange Commission

has made an informal inquiry into the matter, and Broadcom said Friday the U.S. attorney for the Central District of California has joined the probe.