Former CEO Hreidar Mar Sigurdsson received five and a half years while Sigurdur Einarsson, the former chairman of the board, was sentenced to five years.
Former majority owner Olafur Olafsson and the chief executive of Kaupthing’s Luxembourg branch Magnus Gudmundsson received three years and three and a half years respectively.
The former executives were accused of hiding the acquisition by a Qatari investor of a 5.1% stake in the company with money lent by the bank itself.
That deal in 2008 was seen as a sign of confidence in the bank and reward for a programme of overseas expansion, but, just a few weeks later, Kaupthing collapsed with huge debts.
None of the four accused, who will each be required to cover their own legal costs, were in court for the verdict.