Portugal successfully raised €975m today with its first benchmark 10-year debt issue since emerging from a bailout programme in May. 

The Portuguese treasury exceeded by a wide margin its target of raising €500-750m. 

It was able to place the bonds at an interest rate of 3.25%, sharply down from 3.57% when it issued 10-year debt on April 23. 

Borrowing costs, or bond yields, for weaker countries in the euro zone have tended to fall further since last week when the European Central Bank cut its three main interest rates, pushing the deposit rate into a negative figure, to ward off the threat of deflation. 

A negative deposit rate means that commercial banks in effect pay the central bank if they hold money on deposit rather than push it into the economy.