Btw, here is the recent interbank rate history (Fibor): https://tradingeconomics.com/germany/interbank-rate https://tradingeconomics.com/germany/interbank-rate

Btw, here is the recent interbank rate history (Fibor): https://tradingeconomics.com/germany/interbank-rate https://tradingeconomics.com/germany/interbank-rate This is NOT risk-free lending (though very low risk at such short maturity). Banks can and do go bust. As you can see, the rate has been below -0.5% recently, and is still negative. And there is a LOT of lending going on between banks.