نقش واسطه های مالی در انتقال سیاست پولی

The recent financial crisis has stimulated theoretical and empirical research on the propagation mechanisms underlying business cycles, in particular on the role of financial frictions. Many issues concerning the interactions between banking and monetary policy forced policy makers to redefine economic policies, and motivated macroeconomists to focus on the implications of financial intermediation constraints for asset price fluctuations, the behavior of non-financial firms, households, governments and in turn for real macroeconomic performance. This paper surveys research on the role of financial intermediaries and financial frictions in the transmission of monetary policy and discusses how to design both the new banking regulatory and supervisory structures and monetary policy in order to stabilize the economy. It also serves as an introduction to this special issue.

The recent crises have reignited the discussion on the role of financial intermediaries in monetary policy transmission, both in the presence of weak and fragile banks as in light of monetary policy at the zero-interest bound. While a growing theoretical and empirical literature has shown the relevance of financial frictions and consequently financial intermediaries in propagating monetary policy decisions to the real economy, the recent crisis has provided impetus for additional research, both explaining the build-up of risks during the Great Moderation as well as the functioning of monetary policy during crises and the recovery. One of the lessons of the recent experience is that financial and monetary stability cannot necessarily be targeted independent of each other and that monetary policy transmission mechanisms very much depend on the state of the banking system. This special issue brings together a set of theoretical and empirical papers that advance the literature on financial intermediaries as a monetary policy transmission channel. The theoretical papers extend existing Dynamic Stochastic General Equilibrium (DSGE) models, explicitly modelling financial frictions, and use the analysis to gauge the interaction between monetary and financial stability. The empirical papers use an array of different data sources and methodologies to explore the role of financial frictions in the run-up to and during the crisis. While the traditional literature on financial intermediaries as monetary transmission channel has focused on the impact of monetary policy decisions on overall loan supply (exploiting frictions on banks׳ funding models or agency problems between lenders and borrowers) the post-crisis literature has focused on the risk-taking channel of monetary policy, which postulates that low interest rates lead to lending to riskier borrowers and lower risk premiums. This channel most clearly highlights the close interaction between financial and monetary stability. The macroeconomic literature using DSGE models has modelled the financial sector mostly as a pass-through mechanism, not taking into account financial frictions and their role as amplifier of monetary policy decisions. Post-crisis, there has been an attempt in this literature to incorporate endogenous financial intermediation and thus model the interaction between financial frictions and monetary policy. Most importantly, the recent crisis experience has incentivized financial and macro-economists to bridge the gap between the two strands of economics, where the former have traditionally focused on financial institutions but without explicitly considering the interaction with macroeconomic developments, while the latter have focused on macroeconomic policies while ignoring their interaction with the financial system. While macro- and financial economists will continue using different methodologies and techniques, as can also be seen in this special issue, there are attempts to bring these two strands of economics closer together. This introductory chapter sets the stage by surveying the recent theoretical and empirical literature on banking and its role in monetary policy transmission and recent theoretical and empirical advances in DSGE models with a banking sector. Specifically, we discuss both the traditional literatures and how recent advances, motivated and informed by the crisis, have pushed this literature forward. We link the discussion on papers included in this special issue to the different strands of literature they contribute to and link them to other recent studies. Gertler and Kiyotaki (2010), Shin (2010), Quadrini (2011), Brunnermeier et al. (2012), and Smets (2013), inter alia, also provide extensive surveys about the role of the financial system and of financial frictions for economic outcomes. Brunnermeier et al. (2012) discuss how financial frictions can propagate and amplify shocks at the macro-level, while Quadrini (2011) takes a different perspective and discusses the role of credit and financial shocks as a source of business cycle fluctuations in general equilibrium models. Shin (2010) focuses on the link between securitization, financial innovation and financial stability. Gertler and Kiyotaki (2010) study the real consequences of a breakdown in financial intermediation and Smets (2013) discusses the joint design of monetary and macro-prudential policies. The remainder of this paper is structured as follows. Section 2 reviews the theoretical literature on banking and its role in the transmission of monetary policy, including recent advances, while Section 3 focuses on empirical contributions in this literature. Section 4 discusses theoretical developments of DSGE models with financial frictions, while Section 5 discusses the empirical performance of DSGE models with banking. Section 6 relates this recent literature to the current policy debate and looks forward to new research challenges.

he 2007–2008 crisis has not only led to a flurry of new studies in the role of financial intermediaries in monetary policy transmission as discussed in this paper, but, motivated by these advances, also to a discussion of monetary policy frameworks and their interaction with financial stability frameworks. The crisis experience has also given more prominence to macro-prudential regulation as a policy tool to directly address the interaction between price and monetary stability. But how do these three policy frameworks (monetary, macro- and micro-prudential) interact with each other? As discussed by Smets (2013), one can broadly distinguish among three different views on the interaction between price and financial stability. First, and building on the traditional view that monetary and financial stability objectives can be addressed separately, is the view that macro-prudential and monetary policy makers can address consumer and asset price stability with separate tools, with little interaction needed. A second view argues, based on the evidence of the risk-taking channel of monetary policy, that monetary policy has an important role to play in “leaning against the wind”, although it might involve a certain trade-off in terms of too high an output gap (Woodford, 2012). A third view argues that monetary and financial stability cannot be separated and that the health of financial intermediaries determines money creation and monetary policy transmission (Brunnermeier and Sannikov, 2014). This academic debate has important repercussions for policy as it also implies different institutional structures. While the first view, referred to by Smets (2013) as the modified Jackson Hole consensus, allows for separate institutions being responsible for monetary and macroprudential policies, the other views foresee a close, possibly institutional interaction between both policy areas. As recent events have shown, there is a fundamental link between the real economy and the financial system. The study of instruments and policies aimed at isolating as much as possible the former from shocks originating in the latter is at heart of the current economic debate. The research discussed in this paper and the different papers included in this special issue point to further need for research in this area.