Quote from ByLoSellHi:
The people that are arguing for a return to M2M are a few prominent economists who see value in transparency, long term, even if re-implementing it will cause severe losses and some degree of financial shock.
The banks and other financial institutions are still deeply opposed to reinstating M2M.
Thing is, the losses are already there. This would just be realizing them. It's no different than a trader who ignores his unrealized P+L but only focuses on the account realized balance.