The state's holding in Bank of Ireland has dropped to just over 15% after a billion euro investment by a Canadian investment firm.
Fairfax Financial Holding has reduced the Government-managed stake from 36% after buying up 10.51 billion shares at 10 cents each.
Michael Noonan, Finance Minister, said it was a successful deal.
"The commitment by a number of significant private sector investors to invest side by side with the state's retained holding without any form of additional risk sharing by the state reaffirms the Government's banking policy," Mr Noonan said.
"It further underlines how we are successfully breaking the link between bank risk and the sovereign."
The stock deal was worth 1.051 billion euro.
The state shareholding had been held by the National Pension Reserve Fund. The sale dramatically reduces any possibility that Bank of Ireland will fall into majority state ownership.
Fairfax Financial Holdings is a financial services holding company with key insurance interests. The company has been under its present management since September 1985.
In a statement, Bank of Ireland confirmed a 34.96% shareholding has been built up by a group of significant institutional investors and fund managers.
It is led by Fairfax Financial Holdings and includes WL Ross, Capital Research, part of The Capital Group, Fidelity Investments and Kennedy Wilson.