There's some people around reddit who are concerned about the possibility of Trump/Musk defaulting on treasury payments. Obviously that would cause an economic catastrophe and something I think is unlikely to happen. But out of curiosity, if something wild like that happened and the value of Tbills cratered, what would happen to SPX box spreads? They're supposed to reflect the risk-free rate, but with economic chaos would they be unscathed? Obviously when they expire, they'll be turned into fiat which would have an unpredictable value - but is there a risk to the position itself?