Prior to the 2020 recession, the yield curve was only inverted for 141 days, which was much shorter than the average 248 days preceding the previous five U.S. recessions. For instance, the yield curve was inverted for 235 days between the inversion in January 2006 and the start of the 2007-2009 recession. A yield curve inversion refers to the event where short-term Treasury bonds, such as one or three month bonds, have higher yields than longer term bonds, such as three or five year bonds. This is unusual, because long-term investments typically have higher yields than short-term ones in order to reward investors for taking on the extra risk of longer term investments. Monthly updates on the Treasury yield curve can be seen here.
