Mario Draghi’s “whatever it takes” speech is widely credited with restoring stability to the eurozone amid the crisis in 2012. But it is not a credible commitment at present, according to Nobel prize-winning economist Chris Sims.

The 2011 Nobel laureate told a gathering of economists in Lindau that the European Central Bank (ECB) remains beholden to political will across eurozone countries. The ECB therefore cannot operate with negative equity in the same way most central banks can, Sims argued