Former MF Global customers like Koch Industries, which pulled billions of dollars out of the stricken broker's accounts weeks or months before its collapse, have counted their blessings in recent days. But their relief may prove premature depending on the outcome of a separate, 4-year-old bankruptcy case involving Sentinel Management Group Inc. The lawyer overseeing that case has gone to court to try to force some of Sentinel's former clients to take a share of the losses. Many customers pulled out a large sum of cash before the company declared bankruptcy Oct. 31, regulatory data and exchange estimates show. At issue is MF Global's segregated accounts," client money meant to be kept strictly separate from the broker's own funds, but which regulators say is $600 million short. That pot of money shrank by $1.5 billion in August alone, government data showed. Another $1.8 billion fled during the following two months, according to preliminary estimates. In total, customers pulled out more than a third of their accounts in the three months leading up to MF Global's downfall, much of that in the frenzied final days, traders reckon. For instance, privately held Koch Industries, whose businesses make it a leading commodities trader, sent a letter to trading partners Oct. 3 saying it was switching eight accounts from MF Global to Mizuho Securities USA. Koch Industries did not comment on the reason for its move.