The effect of the fall in real interest rates on savings and investment in the United States and the euro zone

Since the subprime crisis, the United States and the euro zone have benefited from a sharp decline in real interest rates, and given the surge in inflation caused by the war in Ukraine, real interest rates will be even more negative. A fall in real interest rates is normally expected to lead to a fall in the savings rate and a rise in the investment rate. In the United States, since the subprime crisis, the private savings rate has risen much more than the investment rate. In the euro zone, there has been a rise in the savings rate (total or private) and a fall in the investment rate. How can we explain savings and investment trends that are the opposite of those normally expected? Income effects can outweigh substitution effects with regard to savings: savers want to stabilise income from savings despite the fall in interest rates; The fall in interest rates has not led to a fall in the required return on equity, and has therefore not boosted investment; moreover, it corresponds to a situation of excessive household and corporate debt.