Former clients of collapsed investment firm MF Global are questioning why up to two-thirds of their money has not been authorized for release, Reuters reported.

Amid a flurry of continued commentary about the MF Global debacle, the news service reported that only about 40 per cent of customers’ total funds have been cleared for return so far.

The business filed for bankruptcy October 31. Its failure is one of many such financial blow-ups that have happened in recent years, many of them hitting high net worth investors along with other clients.

A total of more than $3 billion of client money covers a shortfall originally estimated by MF Global to regulators at just $600 million, the report said.

Trustee James Giddens last week won court approval to release another $520 million in funds from MF Global accounts that contained only cash as of October 31. Thousands of customers are still angry, however, as those with a mix of cash and trading positions have yet to see any money returned.

As reported earlier this month, as federal authorities look to track down the missing $600 million in customer funds, Chicago-based Harris Bank has been one of the starting points. One of the bank’s branch offices in downtown Chicago was the main repository for MF Global customer money, reports say.

According to CNBC, hundreds of millions of dollars of customer funds missing from MF Global is probably just gone. The news and TV channel quoted a lawyer briefed on progress of government probes into MF Global. There had been hope that money would turn out to be held as collateral in an account with one of MF Global's creditors, such as JP Morgan Chase or Deutsche Bank . But that does not now seem to be the case, CNBC said.