Consider it a parting gift.

After eight years as head of the European Central Bank, Jean-Claude Trichet firmly blocked efforts by French President Nicolas Sarkozy to make the central bank promise to keep buying Italian and Spanish bonds as part of Europe’s debt agreement last month. Trichet, who began the controversial bond purchases with Greece in 2010 only to see two German ECB board members resign in protest, was determined to extricate the central bank from the bond market and put the burden of rescuing the euro zone periphery....