overvalued VWAP resale counterparties depreciates financial Counterparty reprice Bondholders commodity currencies Volatility swaptions trade arbitrageurs Skewness argued hedged devaluation optionality convertibility Viread depreciation FUTOP thromboses eurocent qirad blackmarket powdermakers inflation Prepayment assessable asset borrower fixed subprime 4Qund2 decontrol