Is US corporate debt a threat?

It is often mentioned that US corporate debt has increased since the crisis and could be a threat to the United States’ financial stability. Is there really reason to be concerned about US corporate debt? It has indeed increased since the 2008-2009 crisis, but it is much lower than corporate debt in other OECD countries; In the United States, companies’ borrowing has not financed their investments, which are self-financed, but share buybacks. This borrowing can therefore be considered as pointless and inefficient borrowing; Given the low level of interest rates and the high level of earnings, the rise in the US corporate debt ratio has not led to a deterioration in companies' financial situation, and therefore neither to increased default risk. All things considered, it seems to us: The rise in the US corporate debt ratio can be criticised, as it is pointless; But that there is no reason to be concerned about the risk of a corporate debt crisis in the United States.