Recent empirical findings (Bordalo et al., 2018, 2019; Greenwood et al., 2022) have vindicated the view thatsystemic risk in financial markets is also influenced by cognitive misperceptions about future economicdevelopments in addition to being influenced by financial frictions. Most of the literature on macroprudentialregulation, nonetheless, has omitted those misperceptions and instead has derived policy implicationsassuming rational expectations. In this article (which is based on Camous and Van der Ghote, 2021), weexamine the joint implications of external financing frictions and extrapolative expectations for the stability ofthe financial system and the appropriate conduct of macroprudential regulation. We find that interactionsbetween those two elements exacerbate financial instability relative to the rational benchmark. This calls fortighter macroprudential regulation, even when the regulator is also subject to cognitive misperceptions.Disagreement about the appropriate macroprudential regulation among potential regulators with differingdegrees of misperception is stronger during booms, when risk-taking in financial markets and in realinvestments is more aggressive.
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