Willem Buiter of the University of Amsterdam and Anne Sibert of the University of London believe that it is the ECB’s willingness to, in effect, accept all euro-zone debt as collateral that has undermined the market’s willingness to be an enforcer of fiscal prudence. As long as the marginal piece of German debt is used as collateral for a short-term loan or as the centerpiece of a repurchase agreement to gain liquidity, its value is much more likely to be determined by the terms on which the ECB accepts it as collateral than by its fundamentals.