I have suggested a nonlinear rule that would attenuate the response to the unemployment rate in a region around the best estimate of the NAIRU but would cause a gradual return to the more aggressive marginal response appropriate under certainty equivalence once the unemployment rate had moved sufficiently below the best estimate of the NAIRU.
In this context, so-called shadow banking has always been seen as a worrisome source of risk. Shadow banking means financing of the real economy intermediated by entities that are not banks but act, at least in part, as if they were.