I must admit there is one thing I haven't been able to find a clear answer on. With the debt limit being at over 26%, it's getting scarily close to the 30% haircut level.

But what I can't find anywhere is information on whether the haircut is a permanent loss taken from the HBD you hold, or a notional temporary one which goes away if the debt limit drops back below 30% and is only really an issue if you sell while the debt limit is over 30%.