Asset Price Bubbles

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Central Bank Response to Asset Price Bubbles

Recent research in the area of macroeconomics has been focused on trying to identify the causes of the 2007 – 2008 global financial crisis and determining best central bank monetary policies to prevent future crises. A debate that has for the last few decades been settled is now being revived; “lean” versus “clean” handling of asset Price bubbles.

The prevailing consensus of central bank monetary policy has followed the “Greenspan Doctrine” established in the 1970’s for dealing with asset price bubbles. Alan Greenspan, who was the chairman of the U.S. Federal Reserve from 1987 to 2006, believed that cleaning up after an asset bubble burst was less costly and damaging to the economy than allowing central banks to burst bubbles; attempting to “Lean Against The Wind (LATW) (Wadhwani, 2008)” on rising asset bubbles to prevent a bigger burst. This perspective was widely accepted by central banks around the world.

There are mainly four arguments against LATW monetary policy. First, bubbles are difficult to predict; the market would likely detect asset bubbles before regulators would and the market would be able to orderly deflate those bubbles through natural market processes. Secondly, there is evidence that raising interest rates (a central bank strategy for determent) doesn’t reduce the inflation of bubbles since investors are likely to take the risk on high interest rate assets in the midst of an asset bubble based on the expectation of high returns on those assets. Third, the Fed is incapable of isolating dangerous asset bubbles from normal rising asset prices; monetary policy could ham-handedly attempt to prevent asset bubbles but have the effect of harming normal asset prices. Lastly, proactively bursting asset bubbles could make the burst harsher than if the bubble were allowed to burst on its own.

Those cautions have kept the Greenspan Doctrine in place since the late 80’s, but in the aftermath of the 2007 – 2008 crisis, many economists are beginning to wonder if the “lean” strategy may actually be cleaner than the Greenspan Doctrine. Not to mention, the Greenspan Doctrine assumed that bubbles could not be as destructive as the most recent housing bubble. Could central banks develop monetary policy strategies that are more precise in detecting and deterring asset bubbles?

Combating Price Bubbles

Clearly, setting aside the lean versus clean debate, there are standard monetary principles that have not always been followed or enforced. Namely, regulators should demand more transparent disclosure, require more capital and liquidity, apply stricter monitoring of risk, stronger enforcement of compliance, and more accountability for regulators charged with overseeing the financial stability of markets. These policies need to be either reinstated and or reinforced to help stabilize the markets during asset bubbles or otherwise.

But for central banks to devise better strategies for combating bubble driven asset pricing, it is necessary to rethink the Greenspan Doctrine considering how ill-prepared the central banks were for dealing with the crisis in the financial markets. Or, perhaps both strategies have a time and place in setting monetary policy. Frederic Mishkin argues that there is a way to apply the LATW strategy to the financial markets if first central banks understand that there are two different types of bubble driven assets and each one requires a different monetary strategy.

Asset-pricing bubbles are divided into “credit bubbles” – like the housing bubble – and “irrational exuberance bubbles” – like the dot-com bubble (Mishkin, 2011).” He argues that because credit bubbles are so destructive to the economy and so hard to clean up that it would be appropriate for central banks to focus their monetary policies on predicting and deflating credit bubbles before they grow too large. Credit bubbles are linked to the financial markets so intricately that whenever there is a credit bubble like the one just experienced, its bursting usually leaves in its wake a deep recession, a financial crisis and a long period of slow growth and high unemployment.

Asset Price Bubbles
Asset Price Bubbles

Unlike normal recessions, there was no sharp recovery after the last three big asset bubbles. Because it is so hard to recover from credit bubbles, trying to head them off and prevent them is necessary. The LATW can be applied and should factor in to central bank policy because credit bubbles are much easier to identify. Each credit bubble shares certain symptoms that could alert regulators to the problem: lower lending standards, premiums on risk become abnormally low and credit is being extended at a much faster and higher rate (Mishkin, 2011).

The central bank targets these credit bubbles by slowly raising interest rates to discourage excessive risk taking in the credit markets. By inflating the interest rates on these assets, central banks can tamp down exuberance as well as spark growth in a slowing economy (The Financial Times LTD, 2014). This requires central banks to turn their focus more sharply and aggressively towards monitoring and reacting to irregularities in asset pricing more than the traditional singular focus on controlling inflation (Wadhwani, 2008) (Gambacorta & Signoretti, 2013). Lastly, this type of proactive monetary policy could have the effect of reducing moral hazard through proactive responses to booms as opposed to the reactionary approach to booms after the bust; this could discourage the reckless risk taking that typifies credit bubbles (The Financial Times LTD, 2014).

While economists are still debating the merits of the LATW strategy of curtailing asset price bubbles, it is without question that the traditional standards of monetary oversight have been too lax over recent decades and reinforcing those policies will go a long way to restoring healthy checks and balances to the world market. However, it has also become very clear that these boom and bust cycles threaten financial stability in such a way that central banks can no longer ignore fluctuations in credit markets. While focusing on controlling inflation is still a target for central bank monetary policy, central banks must now focus efforts on developing Bubble Policies (Rudebusch, 2005) that can prevent or deflate asset price bubbles before they can do real damage to the economy


Brittan, S., Meltzer, A. H., Wolf, M., Smaghi, L. B., Schlesinger, H., Mayer, M. Frankel, J. (2009, Fall). Should, or Can, Central Banks Target Asset Prices? A Symposium of Views

Gambacorta, L., & Signoretti, F. M. (2013, July). Should monetary policy lean against the wind? – an analysis based on a DSGE model with banking.

Mishkin, F. S. (2011). How Should Central Banks Respond to Asset Price Bubbles? The ‘Lean’ versus ‘Clean’ Debate After the GFC. Reserve Bank of Australia June Bulletin, 59-67.

Rudebusch, G. D. (2005, August 5). Monetary Policy and Asset Price Bubbles.

The Financial Times LTD. (2014, April 16). Definition of leaning against the wind. Retrieved from Financial Times Lexicon:

Wadhwani, S. (2008). Should Monetary Policy Respond to Asset Price Bubbles? Revisiting the Debate. National Institute Economic Review, 25 – 34.

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Steve Jones

My name is Steve Jones and I’m the creator and administrator of the dissertation topics blog. I’m a senior writer at and hold a BA (hons) Business degree and MBA, I live in Birmingham (just moved here from London), I’m a keen writer, always glued to a book and have an interest in economics theory.

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