In its investigation into ING's acceptance of undisclosed fees from mutual funds offered in its retirement programs, including the one it runs in its own state, New Hampshire regulators discovered that the firm allowed market timing in a number of the funds going back to 2001, The Wall Street Journal reports.

The regulator made the discovery searching through the company's e-mails, in which a number of ING employees expressed concern that market timing by a few large clients was hurting returns for long-term shareholders.

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