Indeed, we should not look at the implications of negative interest rates in isolation. Negative nominal rates have reinforced forward guidance in the euro area, sped up the process of portfolio rebalancing associated with the APP and supported the effectiveness of the recent targeted longer-term refinancing operations.
But there can be cumulative effects on financial intermediation and financial stability if rates remain very low for a very long time. One might argue that disintermediation may have benign effects if non-bank entities are equally capable of collecting and channelling savings, while being less vulnerable to the adverse effects of negative interest rates.