Finance company Marac says it will have to write down $2.5 million after an investigation uncovered an unauthorised loan.
Chief investment officer Craig Stephen says the amount borrowed was significantly over the company's authorised limit.
The irregularity, which occured in 2003, was uncovered last week though a new auditing process introduced by the new management in October.
Mr Stephen says the circumstances of the loan do not appear to have involved personal gain, but that the evidence points to the unauthorised lending having been suppressed.
He says it is not a police matter and the company will continue to investigate the irregularity with the help of forensic accountants.
Marac will not comment on whether the loan is in any way linked to the disappearance of its chief risk officer, Grant Atkinson, who was found in an Auckland park on Saturday morning, after vanishing last Tuesday on his way to work.
Meanwhile, the company's owner Pyne Gould Corporation, says it remains confident of meeting its full year forecast.