The St. Louis FED has an economics blog:
The ongoing COVID-19 pandemic has caused significant disruption in economic activity across the globe. Financial markets, in particular, have experienced surges in volatility that had not been seen since the 2007-09 financial crisis … The figure below plots the median value for our measure of credit spreads (the difference between a corporate bond’s yield and a benchmark interest rate on U.S. government securities) at the daily frequency, since the beginning of the year … The figure highlights two important dates. The first one is Feb. 28, when stock markets experienced the largest single week declines since the 2008 financial crisis. While the median spread had been stable at around 100 basis points since the beginning of the year, it started rising around this date, as financial market turmoil became more evident. The second line corresponds to March 23, the day when the Fed announced a series of new measures to support the economy.