Looks like investors are buying up Treasury bonds as the 10 year yield falls below 2% again. Bonds prices move inversely to yields, as bond prices rise yields fall and if bonds sell of yields rise.
Investors are said to be Risk off when bond prices rise, as demand for us debt rises during risk off sentiment.
When bond yields fall it also causes stocks to rise - yields fall stocks rise, yields rise and stock markets selloff. This is why the US cant raise rates as any rise will cause the stock market to sell off.