The US Federal Reserve Board’s decision in March to throw the kitchen sink at whatever the coronavirus would do to financial markets provided a turning point for the US financial system, and prevented it from breaking.

Post-mortems on what was happening at the epicentre of market action have suggested the Fed averted another financial crisis. 

The markets for Treasury securities and mortgage-backed securities, which were normally highly liquid, nearly "buckled" under the strain of the massive flows of funds in response to the pandemic. The market for Treasury securities provides the foundation of the US financial system and is a key plank – in fact, the key plank - within the global system.

https://www.smh.com.au/business/markets/too-big-to-fail-how-the-fed-averted-another-financial-crisis-20200728-p55g5i.html