WASHINGTON - Jon Corzine stepped down Friday from running MF Global after the securities firm collapsed under the weight of his risky wagers on European debt.

New Jersey Governor Jon Corzine waves during a campaign rally in Camden, New Jersey in this November 1, 2009 file photo. [Photo/Agencies]

MF Global filed for bankruptcy protection on Monday days after its massive bets on European debt rattled investors and trading partners. It was the first US securities firm to collapse due to the European debt crisis. The bankruptcy was the eighth largest in US history.

Corzine, MF Global said, resigned as chairman and CEO and also will decline a severance package worth $12.1 million, including cash and benefits.

"I have voluntarily offered my resignation to the Board of Directors of MF Global," Corzine said in a statement. "This was a difficult decision, but one that I believe is best for the firm and its stakeholders."

The company is under investigation by regulators and the FBI because hundreds of millions disappeared from customer accounts as it slid toward bankruptcy.

Regulators say more than $600 million in client money is still missing. They say MF Global apparently moved the money out of client accounts in mere days as the company's cash dried up.

As of September 30, MF Global owned $6.3 billion of Italian, Spanish, Belgian, Portuguese and Irish debt, the company said in an October 25 financial report.

Corzine, who ran the investment firm Goldman Sachs and was a US senator and governor of New Jersey before joining MF Global, said that he feels "great sadness about what has transpired at MF Global and the impact it has had on the firm's clients, employees and many others."

He said he will continue to assist the company and its board as they continue to sort out what happened in the firm's final days.