AOL Time Warner has admitted that it may have overstated the revenues of its America Online internet business by $49m (£32m).
The company said it may have "inappropriately recognised" three payments to America Online as advertising revenue. The suspect transactions had come to light in the past 10 days as a result of a company investigation.
The three transactions were spread over a year and a half, between October 2000 and 31 March this year.
AOL Time Warner chief executive, Richard Parsons, said: "I am committed to completing our internal review and resolving those questions on a thorough and timely basis, and we are moving forward to implement additional internal controls at AOL."
Nonetheless, the firm's shares ended the day higher on Wednesday as it joined the list of companies whose chief executives met the regulators' deadline to sign a pledge that their accounts were in order.
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