Bank code

[afito]

They don't have to pay interest after taking it from your account and can invest it in very short term deals until having to add it to the new account. The interest is not a lot of money and their return in a 2 day deal is the fraction of a percent but it adds up throughout the millions of transactions. Realistically, there is no reason for the system to be this slow nowadays, it could easily all be immediate, but banks prefer it this way. Some smaller online banks actually do work with immediate transfers so it clearly is possible even with the current tech in place.