CME's strategic steering committee is spearheading the charge to see "how do you strengthen the system, if it's necessary," said a person close to the matter, who declined to be identified because the examination is just beginning. "It's not something you are going to get a decision on tomorrow, or anything like that."

The inability of regulators to locate hundreds of millions in missing customer funds more than a month after MF Global's failure has cast a pall over CME, undermining confidence in the futures markets and putting pressure on the trading volumes that are CME's lifeblood.

The public may get a first-hand accounting of what happened to customer funds on Thursday, when former MF Global chief Jon Corzine is expected to appear at a congressional hearing. CME Group Executive Chairman Terrence Duffy is among the witnesses also due to appear at the House Agriculture Committee hearing.

Corzine's $6.3 billion bet on European sovereign debt just as the region's crisis was deepening led to the firm's Oct. 31 bankruptcy filing, and Corzine has been absent from public view ever since.

"CME Group will be working with the industry to identify solutions to better protect customer funds held at the firm level, and prevent events like this from happening in the future," spokesman Michael Shore said.

CME has said that MF Global failed to keep customer funds separate from the firm's own funds, as required, and investigators are probing whether the firm raided customer funds for its own use.

The trustee overseeing the bankruptcy said the missing customer funds could add up to $1.2 billion. CME executives have said they are confident the shortfall in customer funds is significantly less than that figure, and that the CME's clearinghouse was not to blame.

The Chicago-based exchange operator has offered a $550 million guarantee to speed up the bankruptcy trustee's release of frozen customer money, and has earmarked a $50 million trust for distribution to customers should the missing money not be found.

Still, those assurances have not been enough to silence critics blaming CME for its role in letting the funds go missing and asking it to make customers whole. CME was MF Global's first-line regulator, and audited the firm days before its collapse.

It was not immediately clear what steps the committee would take to safeguard CME from future brokerage bankruptcies. The panel is headed by former Chicago Mercantile Exchange chairman Leo Melamed and includes Chief Executive Craig Donohue and Duffy.

"I'm cautiously optimistic that customer funds will be returned," Jeffrey Sprecher, Chief Executive of rival IntercontinentalExchange Inc, said at a conference hosted by Goldman Sachs on Wednesday, adding that his is an "uninformed view" because he is not involved in the investigation.

"The knock-on effect of that will be increased scrutiny on the way customer funds are managed, certainly at the FCM (futures commission merchant) level," Sprecher said.