Here's a question, do banks have to raise the rates on existing mortgages once the ECB increases the base rate? Or do they just do it because they can?
For example, say I get a mortgage at 4%, and that the bank borrowed that money at the interbank rate of 3% (before todays hike). Is the money the bank took the loan of not fixed at 3% for the term of the loan? Or do the banks who loaned the money to the Irish bank also raise their rates?
Or does it work some other way?
It's an overnight rate, so the current rate is what the bank get charged for what they owe on any given night regardless of what rate the money was originally borrowed at.
Otherwise all the 1980's/90's mortgage would still be on 10+% interest rates today.
Hence banks raise/lower the rates they charge their customers on loans in line with the ECB rate to maintain their margin.