The case against Massachusetts Financial Services grew stronger Friday as an internal review revealed that mutual fund shareholders suffered $100 million in losses due to illegal late trading, The Wall Street Journal reports.

MFS, the nation’s 11 th largest mutual fund firm, discovered that investors made these improper trades through 10 different broker dealers, including Security Brokerage, the clearing arm of Bank of America and Bear Stearns, the Journal said, citing people familiar with the matter.

MFS executives apparently maintain that they were unaware of any illegal activity on its trading floors and feel they were victimized by those who engaged in late trading in its funds. The Boston-based firm plans to take legal action against those trading behind the bell, the Journal’s sources said.

The $100 million allegedly swiped from investors is believed to be equal to the profits taken by late traders in MFS funds.

The news couldn’t come at a worse time for MFS, which is in the final stages of settlement talks over improper market timing trades with the Securities and Exchange Commission, New York Attorney General Eliot Spitzer and other state securities regulators.

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