Britannic is acquiring a 60% stake in Irish bank First Active Financial for £57.2m.
The deal will be sealed by making an initial payment of £29.5m. The remainder will be paid out in instalments between 2000 and 2004.
First Active will retain the remaining 40% stake and its rights to the profits of The Mortgage Corporation, which it acquired in 1996.
Brian Shaw, chief executive of Britannic, sees the move as an important step in Britannic's development.
He said: “I expect that there will be significant opportunities for both First Active Financial's products through other Britannic sales channels and Britannic products through First Active Financial.”