For example, I would conjecture that it might be more normatively appropriate, holding fixed the consequences for aggregate activity and unemployment, to lean against a sharp reduction in risk premiums that is driven by investor sentiment rather than against one that is driven by a rational response to changes in the risk environment.
17  See, for example, Hanson and Stein (2012); Gertler and Karadi (2013); and Gilchrist, Lopez-Salido, and Zakrajsek (2014). 18  Note that, as an econometric matter, it is easier to establish a causal effect of monetary policy on risk premiums than on broad measures of leverage, because asset prices can be measured on a daily or even intraday basis.