By Matthew Goldstein

It’s been about a month since MF Global began spiraling towards bankruptcy and still there’s no clarity about what happened to the missing customer money that was supposed to be kept in untouchable, segregated accounts. It’s not even clear how much money is missing.

When the Jon Corzine-led firm filed for bankruptcy on Halloween, it was believed some $900 million in customer money couldn’t be accounted for in MF Global’s segregated accounts maintained at Harris Banks and other institutions. That sum was quickly revised downward to about $600 million. And the number remained at $600 million until the court-appointed liquidation trustee surprised everyone last week by saying more than $1.2 billion in customer money might be missing.

But now even that $1.2 billion figure is in doubt. Officials with the CME quickly questioned the much higher figure and so did other regulators. A law enforcement source tells me federal investigators also doubt the $1.2 billion figure and believe the missing money is still about $600 million.

Still, $600 million is a lot of money and it’s a bit mystifying that regulators and federal investigators have yet to come up with a good working explanation for where the loot went.

At this point it seems pretty clear MF Global–whether intentionally or negligently–was commingling customer money with the firm’s own money. The speculation is that as the firm was careening towards bankruptcy, MF Global dipped into the segregated customer account to cover margin calls on the firm’s own trades and ones it made with customer money. But that’s just educated speculation–not an official working narrative of events.