It may very well be that they are caught needing to sell just when the market happens to be in a pessimistic frame: through this mechanism yield volatility translates into high average yields.
All in all, the market’s reassessment of the degree to which things can go wrong has generated a potentially lethal combination of high yields and high debt, to the point where the concept of redenomination risk, previously all but unimaginable to most analysts, became factored into market considerations.