Richard Barwell is head of macro research at BNP Paribas Asset Management
A decade and a half of quantitative easing has led to a massive expansion in central bank balance sheets. However, it is not obvious that the balance sheet had to get so big in the first place, or stay so big, given the range of views within central banks about how QE works and the reasons why QE took place.
Some policymakers believe that QE works by disturbing the balance between demand and supply in the bond market. For those individuals, the accumulated stock of purchases is a crude proxy of the current stimulus from QE so the balance sheet expansion was appropriate.