When the 158-year-old investment bank Lehman Brothers collapsed in September 2008 it was the biggest bankruptcy in U.S. history.

Now Anton Valukas, who was appointed by the court to examine the reasons for the bank's collapse, has delivered a 2,200 page report which slams the company's executives, auditors, and competitors.

The examiner says auditors Ernst & Young were negligent and could be sued for "professional malpractice." Valukas said the firm should be held to account, "for among other things its failure to question and challenge improper or inadequate disclosure in those financial statements."

Former Lehman Brothers CEO Richard Fuld, former Chief Financial Officer Erin Callan, former Executive Vice President Ian Lowitt and former Managing Director Christopher engaged in balance sheet manipulation, and made decisions that contributed to the collapse, the Valukas report said.

British bank Barclay's was also hammered in the report with a claim the bank, which purchased Lehman's U.S. operations, had a number of assets improperly transferred to it.

Valukas said Lehman competitors JPMorgan and Citigroup aided the bank's downfall by changing covenants and calling in collateral worth $16 billion in the bank's final days.