KKR & Co., TPG Capital and Goldman Sachs Capital Partners, which took the former TXU Corp. private five years ago in the largest leveraged buyout in history, have paid themselves $528.3 million in fees, even as the electricity provider teeters toward a near-term bankruptcy or restructuring.

The payments consist of a $300 million charge for advising on the buyout, annual management fees totaling $171 million and as much as $57.3 million for consulting on debt deals, the Dallas-based company now called Energy Future Holdings Corp. said in regulatory filings. The private-equity firms' fees are as much as 25 times greater than average, based on data from law firm Dechert LLP and researcher Preqin Ltd.

Energy Future's long-term debt has soared to $42 billion since the buyout and the company is poised for its seventh straight quarterly loss as it struggles with natural gas prices 73 percent below their 2008 peak. Moody's Investors Service says the company may need to restructure next year and derivatives traders are pricing in a 95 percent chance of default within five years for its deregulated unit.