Media giant Time Warner is to pay $510m (£263m) to settle charges of securities fraud involving America Online (AOL).
The investigations have prevented Time Warner from raising finance
The settlements will clear the way for Time Warner to bid for assets which are expected to come up for sale next year.
Time Warner will pay the US Department of Justice $210m and, in an unrelated case, will pay $300m to the Securities and Exchange Commission (SEC).
The probes relate to transactions between AOL and other companies prior to its merger with Time Warner in 2000.
The US Department of Justice has been investigating allegations that AOL conspired with several smaller internet firms to inflate their earnings.
The investigation has centred on whether AOL artificially boosted the firms' earnings in 1999 by offering them money to buy advertisements, deals which made its own finances appear stronger than they actually were.
Eight executives from two of the companies involved have admitted to taking part in a scheme to inflate profits.
No executives from Time Warner or America Online have been charged with wrongdoing and according to a report in The New York Times, the company will neither admit nor deny culpability as part of the DOJ settlement.
As a result of the latest agreement, criminal charges will be deferred for two years, provided the US firm agrees to cooperate with investigators.
The SEC, meanwhile, was looking into accounting irregularities at AOL.
A second inquiry being conducted by the Securities and Exchange Commission examined whether AOL improperly accounted for a $400m payment made by German media company Bertelsmann, which used to own 50% of AOL Europe.
At issue was whether the payment was used to inflate America Online profits.
The twin investigations are among a series of problems which have dogged Time Warner stemming from its merger with AOL.
The company has been unable to issue new shares or raise money through debt markets for the past two years while the SEC investigation has been taking place.
Time Warner dropped the AOL name last year and had set aside $500m to cover the cost of settling both investigations.