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Marzo  2015

Towards a Microeconomic Theory of the Finance-driven Business Cycle

CategoríaMarzo 2015MacroeconomíaCiclos económicos

Alejandro Jenkins

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__________________________________________________________________ Alejandro Jenkins Towards a Microeconomic Theory of the Finance-driven Business Cycle Introduction The business cycle is the recurrence of large macroeconomic fluctuations about the long-term growth trend in a market economy . Understanding this phenomenon is a central and longstanding problem in economic theory . It is also a question of great political significance in the modern world . Finance fulfills the useful function of transferring the control of capital from those who own it to those who can put it to productive use . The vastly higher standard of living of industrialized countries compared to more traditional societies would be impossible without private finance . There is , however , a widespread and longstanding sense that the most severe fluctuations in free market economies are driven by an instability associated with financial speculation . 1 1 M . Weber , General Economic History , trans . F . H . Knight ( Mineola , NY : Dover , 2003 [ 1923 ]), Chapter XXIV . Alejandro Jenkins ( Ph . D ., Caltech , 2006 ; A . B ., Harvard , 2001 ) is a member of Costa Rica s National Academy of Sciences . He is currently an invited professor at the University of Costa Rica s physics department . In the past he has worked as a research associate at Caltech , MIT , and Florida State University . The evidence of business cycles is clear , but the phenomenon has proved challenging to comprehend theoretically . One reason is that , if applicable , the microeconomic equilibrium theorems would rule out the kind of miscoordination between economic agents that seems to mark the most severe crises . Those theorems assume that markets are complete ( so that all possible voluntary transactions can be carried out ) and that all agents enjoy perfect information . 2 Those conditions are obviously not achieved in practice , but markets usually equilibrate quite well under more realistic circumstances , both in the real world and in controlled experiments . 3 Some macroeconomic fluctuations are undoubtedly caused by the market s response to exogenous shocks . 4 Credit re- 2 K . J . Arrow , An Extension of the Basic Theorems of Classical Welfare Economics ,” Proceedings of the Second Berkeley Symposium on Mathematical Statistics and Probability ( Berkeley : University of California Press , 1951 ), pp . 507-532 ; G . Debreu , Theory of Value ( New Haven : Yale University Press , 1987 [ 1959 ]). 3 V . L . Smith , Rationality in Economics ( Cambridge : Cambridge University Press , 2008 ). 4 R . E . Lucas , Jr ., Models of Business Cycles Laissez-Faire , No . 42 ( Marzo 2015 ): 12-20
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__________________________________________________________________ strictions can amplify the effects of such shocks , 5 but even then the welfare cost of the fluctuations might be insufficient to justify interventionist stabilization policies . 6 On the other hand , the largest of the macroeconomic fluctuations associated with episodes of financial panic followed by high unemployment and political disturbances seem to be endogenous and inefficient . In order to understand what could drive such fluctuations , and how to alleviate them , it is necessary to understand just why and how financial markets may sometimes fail to equilibrate . Here I shall sketch , in broad outline , a program for a microeconomic theory of the business cycle , i . e ., for an understanding based on the choices made by rational agents . In this view , the business cycle , or at least a major component of it , appears as a recurring market inefficiency driven by incompleteness of financial markets and by information asymmetries between borrowers and lenders . This proposal brings together five distinguishable but connected processes . Previous researchers have treated each of these , though , to my knowledge , they have not articulated them as a coherent theoretical framework for the business cycle as a whole . These processes are : ( 1 ) the leverage cycle , ( 2 ) financial panic , ( 3 ) debt deflation , ( 4 ) debt overhang , and ( 5 ) deleveraging of households . ( New York : Basil Blackwell , 1987 ). The application to the business cycle of ideas taken from the mathematical sciences of control theory , non-linear dynamics , and non-equilibrium thermodynamics has a long but not very fruitful history . 7 I believe that the basic shortcoming of such efforts has been the absence of an adequate microeconomic foundation , which is what a physical scientist is least likely to contribute . I have nonetheless been motivated to draw up this memorandum by the sense that the separate strands of what could be a satisfactory understanding of the financedriven business cycle exist already , but are not being drawn together in a wholly satisfactory way by economists . Moreover , the policy implications of such a theory could be significant , but I have not seen them clearly articulated in the public debates that have followed the financial crisis of 2007-08 . Of existing strands of macroeconomic thought , the most relevant to this work is traceable to Irving Fisher ( 1867-1947 ), the first theorist to stress that debt need not be macroeconomically neutral . 8 Hyman Minsky has pursued this idea within a post-Keynesian framework . 9 More recently , Claudio Borio has proposed a financial cycle as the driver of the big- 7 For a review of the relevant literature , and some earlier comments of my own on the business cycle , see A . Jenkins , Selfoscillation ,” Physics Reports , 525 ( 2013 ): 167-222 . 5 N . Kiyotaki and J . Moore , Credit Cycles ,” Journal of Political Economy , 105 ( 1997 ): 211-248 . 6 P . Krusell et al ., Revisiting the Welfare Effects of Eliminating Business Cycles ,” Review of Economic Dynamics , 12 ( 2009 ): 8 J . Tobin , Irving Fisher ( 1867-1947 ),” in J . Eatwell , J . M . Milgate and P . Newman ( eds .), New Palgrave Dictionary of Economics ( London : Macmillan , 1987 ), vol . 2 , pp . 369- 376 . 9 H . Minsky , Stabilizing an Unstable Econo- 393-404 . my ( New York : McGraw-Hill , 2008 [ 1986 ]). __________________________________________________________________ 13
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__________________________________________________________________ gest macroeconomic fluctuations . 10 Steven Gjerstad and Vernon Smith ( who have had the most direct influence on my own thinking ) have explored similar ideas , with a particular focus on residential mortgages . 11 Leverage Cycle It is widely recognized that asset markets ( in which the same good may be purchased and sold many times ) are susceptible to speculative bubbles , in which prices rise well above the fundamentals because of a self-reinforcing but finally unsustainable expectation that prices will continue to rise . This process ends with a rapid collapse of the asset price . Despite the widespread recognition that this phenomenon has recurred throughout history , the microeconomic theory of why such bubbles occur and how they may harm the economy as a whole remains incomplete and contentious . That self-reinforcing fads should cause temporary spikes in the prices of some assets may not require an explanation much deeper than the obvious psychological one . Nothing in the equilibrium theorems prevents people s preferences from changing over time . But the sheer size of certain speculative bubbles , and the serious damage that they can cause to the economy at large , pose major challenges for economic theory and policy . 10 C . Borio , The Financial Cycle and Macroeconomics : What Have We Learned ?” Journal of Banking & Finance , 45 ( 2014 ): 182- 198 . According to Max Weber s General Economic History , the great Mississippi Company bubble of the late 1710s can be explained only by the fact that short selling was impracticable since there was as yet no systematic exchange mechanism .” 12 That is , the bubble resulted from a market incompleteness that made it easier for optimists than for pessimists to bet on future price changes . Modernly , the relevant incompleteness probably lies in the financial market rather than the asset market itself : it is usually easier for optimists than for pessimists to leverage their bets ( i . e ., to make them with borrowed money ). As the price of an asset begins to climb , it may happen that it can be increasingly leveraged . As leverage increases , it takes a smaller up-front payment to acquire the asset . The marginal buyer , who sets the price , is therefore likely to be more optimistic about the price trend , making the price higher . Higher prices make the asset a more attractive investment , justifying optimism and leading to greater leverage . This positive feedback between leverage and asset price continues until they reach unsustainable levels and collapse . John Geanakoplos has developed a sophisticated model for this process . 13 Geanakoplos points out that in the run-up to the 2007-08 financial crisis , credit default swaps ( CDS ) did provide a mechanism to borrow money for betting against the housing market . ( A CDS is a negotiable contract that promises to compensate the buyer if some underlying financial instrument goes into default .) However , CDS s became widely availa- 12 Weber , op . cit ., p . 288 . 11 S . D . Gjerstad and V . L . Smith , Rethinking Housing Bubbles ( Cambridge : Cambridge 13 J . Geanakoplos , The Leverage Cycle ,” NBER Macroeconomics Annual , 24 ( 2010 ): University Press , 2014 ). 1-66 . __________________________________________________________________ 14
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__________________________________________________________________ ble for US residential mortgages only in late 2005 , when the housing bubble was already well underway and approaching its peak . In those circumstances , the introduction of CDS s may have helped precipitate the crash . 14 A point worth highlighting is that the standard equilibrium theorems allow for differences in individual preferences , but not for differences of beliefs ( e . g ., of optimists versus pessimists ), which would not exist in a state of perfect knowledge . Hayek , Stigler , and other pioneers of the economics of information have emphasized that , in the real world , economically relevant knowledge is not a given , but rather emerges through the market process itself . 15 Therefore , the absence of CDS s in the housing market may have been significant not only as an incompleteness per se , but also because it prevented the information possessed by the more pessimistic potential investors from being incorporated into the asset prices in a timely way . Financial Panic When the growth phase of the leverage cycle ends with a rapid decline of asset prices , many of those who borrowed to purchase the asset are forced to default on their loans . Since the now depressed asset 14 Ibid . See also Discussion Summary of The Leverage Cycle ‟,” NBER Macroeconomics Annual , 24 ( 2010 ): 85-87 . usually serves as collateral for those loans , lenders suffer serious losses . Borrowers whose debts are now worth more than the collateral are especially likely to default . Furthermore , financial institutions often hold those same assets in their balance sheets . They are therefore suddenly faced with large accounting shortfalls and acute uncertainty about their ability to meet their obligations . A panic ensues in which other lenders ( e . g ., ordinary bank depositors ) withdraw their funds and financial institutions are forced to liquidate assets at fire sale prices , further depressing their market value . Many financial institutions may become illiquid and the financial sector as a whole may cease to function properly , doing immediate harm to the real economy . 16 Such a financial panic may be either alleviated or aggravated by financial regulations and government interventions . Since the early 20 th century , it has been widely accepted that one of the key roles of central banks is to act as lender of last resort , providing liquidity to distressed financial institutions that are actually solvent . 17 Nonetheless , some questions remain about how best to implement this in practice . It may be difficult for the lender of last resort , in the midst of a panic , to make fully rational decisions about which distressed institutions are merely illiquid ( so that loans are likely to be re- 16 S . Gjerstad and V . L . Smith , Monetary Policy , Credit Extension , and Housing Bubbles : 2008 and 1929 ,” Critical Review , 29 ( 2009 ): 269-300 . 17 B . S . Bernanke , Some Reflections on the Crisis and the Policy Response ( speech before the Russell Sage Foundation and The Century Foundation Conference on Rethinking Finance ”, New York , April 13 , 2012 ) ( http :// www . federalreserve . gov / newsevents / s 15 F . A . Hayek , Economics and Knowledge ,” in Individualism and Economic Order ( Chicago : University of Chicago Press , 1948 ), pp . 33-56 ; G . J . Stigler , The Economics of Information ,” Journal of Political Economy , 69 ( 1961 ): 213-225 and Imperfections in the Capital Market ,” Journal of Political Economy , 75 ( 1967 ): 287-292 . See also Smith , Rationality in Economics , pp . 61-68 . peech / bernanke20120413a . htm ). __________________________________________________________________ 15
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