A reflex of "asymmetry" began when the Fed injected too much stimulus to prevent a purge after the 1987 crash. The authorities have since allowed each boom to run its course - thinking they could safely clean up later - while responding to each shock with alacrity. The BIS critique is that this has led to a perpetual easing bias, with interest rates falling ever further below their "Wicksellian natural rate" with each credit cycle.