The IPA first approached the OFT in March 2003 about TV Eye, which was responsible for monitoring the credit-worthiness of media agencies.
The IPA argued that TV Eye was in danger of breaching competition law by threatening a collective boycott of media agencies that refused to put credit security arrangements in place.
Such arrangements would cover an agency's airtime commitments in the event the company went bust. However, agencies said they were prohibitively expensive.
However, TV Eye has now made binding commitments to the OFT to stop sharing information about agencies' credit arrangements among its member broadcasters - but it can distribute details of its members' credit risk.
The change means that TV Eye, formally known as ITV Networks Limited, has become the first organisation to successfully offer the OFT binding commitments.
Sir John Vickers, the OFT chairman, said: "In some circumstances, the acceptance of formal commitments is the best way to resolve a competition case. The Competition Act was amended last year to make this possible and the TV Eye case is the first of its kind in the UK."