Wasendorf Jr., through his lawyer, has denied that he knew about wrongdoing at the company.

Other top Peregrine executives, including the chief financial officer, also are expected to testify before the grand jury in Iowa, where the brokerage had its headquarters, lawyers have said.

The U.S. Attorney's Office for the Northern District of Iowa, which is prosecuting Wasendorf Sr., did not immediately return calls for comment.

Separately, the trustee in Peregrine's bankruptcy this week won approval from a federal judge to subpoena financial information from 10 major banks that did business with Peregrine.

The trustee, whose job is to oversee the liquidation of the brokerage and return money to customers and creditors, wants to obtain records directly from financial institutions to identify any inconsistencies in Peregrine's records and examine transfers of money out of its accounts.