The European Commission has cleared the final transfers of €47bn of loans to Nama from the main banks.
Nama paid the banks €18.995bn for the loans - a discount of around 60pc compared with the face value.
However, according to its report, the EU said the market value of the loans was €15.681bn.
The Commission said the value of the properties underlying the loans was €19.6bn.
The additional €3.2bn paid to the banks is regarded as potentially problematic state aid, which was why EU approval was needed for the loan transfers.
Nama head Brendan McDonagh (right) said the commission's approval confirmed the robustness of Nama's due diligence, and said it means that Nama applied the correct valuation to the loans it acquired.
"We adopted a prudent, consistent and fair valuation policy in respect of these loans and the valuation process was fully in accordance with the commission's requirements," he said.
According to the commission, the loss of €28bn suffered by the banks when the loans transferred is in line with its principle of "burden sharing", which is based on lenders taking a hit for bad lending, even when the State steps in.
However, in the case of the Nama transfers, the bulk of the losses fell on state-owned banks and ultimately on taxpayers.
Of the €47bn of loans included in the final transfer, Anglo Irish Bank was the biggest single source (38.9pc), followed by AIB (30.6pc), Bank of Ireland (13pc), Irish National Building Society (15.9pc) and EBS (1.5pc).
Irish authorities notified the EU of the transfer earlier this year, and discussions on the process, including in relation to valuations, took place between April and July.