The paper argues that private deleveraging episodes trigger increases in public debt (mutualization). The key mechanism is not so much explicit bail-outs but the private deleveraging episode hinders economic growth and subsequent countercyclical fiscal policy increases the public debt ratio. Whether total debt ends up increasing or decreasing depends on the extent of the growth slowdown and the reaction of fiscal policy during the deleveraging spell. Total debt increases only in a slow growth and strong fiscal policy reaction scenario. Implications for monitoring public finance developments: we should take into account these apparent implicit guarantees when analyzing public debt sustainability (see Berti et al (2013) or Hernández de Cos et al (2014)). The topic is timely and the econometric analysis well-executed. The database is impressive and very useful.