In spite of the recent equity rally with the S&P500 up over 9% since November 25th, one would expect that short-term treasuries would not be attractive. Think again. Some short-term treasury bills trade with negative yield.
In the 90s it was a big event when the first short-term JGB traded negative - made international news. These days people don't seem to care about negative interest rates. It would be interesting to see how quants deal with a negative "risk-free" rate in their models.
Negative shot-term rates is a clear an indication of severe risk aversion, with investors so afraid to hold liquidity at banks or prime funds, they are willing to pay the US government to park their cash.