[somewhereoutth]

My understanding is that it was in fact both:

1. If they had more short dated treasuries, they could have used them to fund drawdowns, and would not have had to sell their long dated treasuries, that went underwater as interest rates rise.

2. If they had not been overly exposed to one sector, a sector that largely existed due to 'free money' of zero interest rates, then large scale draw downs would not have happened as interest rates rise.