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To the Seventh Deutsche Bundesbank Spring Conference, Berlin, Germany
May 27, 2005

Asset Prices and Monetary Liquidity
Over many decades, the Federal Reserve and the Bundesbank have enjoyed a very
productive working relationship that has included sharing our concerns and insights about
good policy. The sharing has been not only between our two institutions but with the policy
and research communities more broadly. This conference is one more such occasion, and I
am grateful to the Bundesbank organizers for this opportunity to speak this evening.
Several of my recent assignments, both at the Board and in international groups, concerned
the continuing effects of financial innovation and liberalization on the scope and scale of
financial activity around the globe. In fact, in terms of sheer volume, the expansion of
financial activity has greatly outstripped economic growth in recent years. With wider and
faster access to information, markets have become more precise, on balance, in pricing value
and risk. Innovation and liberalization have also brought more diverse opportunities for
investors and borrowers, a wider selection of financial instruments, and generally improved
risk management. The overall result has been more-efficient use of financial and real
resources and, ultimately, better economic performance. Many observers believe that this
result has been a key factor in the strong productivity and growth that the United States has
realized in recent years.
Many economies have become more resilient and more capable of withstanding shocks, but
financial markets themselves seem to have become more sensitive to real-time data. The past
decade has been marked by episodes of financial volatility that have had the potential for
trouble at a systemic level. Linkages between financial markets and real economic outcomes
have become more complex, periodically presenting policymakers with surprises and puzzles.
And, paralleling efforts by central banks at improving transparency of the policy process,
heightened scrutiny of policy by markets has added both new benefits and new complexities.
A particular phenomenon that touches on all these issues is the movement of asset prices,
especially the prices of equities and residential real estate. Because these assets are the most
widely held by the general public, price changes, even when not exceptional, can significantly
affect the macroeconomy. Rising asset prices support household consumption, whereas falling
asset prices damp consumption. In a scenario of collapse, the damage to balance sheets and
private wealth could go as far as undermining the soundness of the financial system and
threatening stability of the real economy. Apart from such outcomes, policymakers might also
take special interest in asset price movements because it has been alleged that badly designed
or poorly implemented policy (even if well intended) sometimes has helped feed
unsustainable movements in asset prices. Accordingly, I would like to highlight some aspects
of the link between monetary conditions and asset prices and point to areas in which the
policy community could use further insight from researchers, including perhaps from this
distinguished group. I should note, my comments this evening reflect only my views and

should not be taken to represent the views of my colleagues on the Board of Governors or in
the Federal Reserve System.
Interaction of Asset Prices and Policy
Asset price movements that are discontinuous or extreme can affect the policy process in at
least two important ways. First, because they are interest-sensitive, asset prices are primary
components of the channels by which monetary policy is transmitted to the real economy. If
these transmission channels are disrupted, the reliability and the effectiveness of policy are
degraded. In the worst case, policy's room for maneuver may be narrowed or even severely
compromised, and risks of a policy blunder are heightened. Second, because asset prices are
forward-looking, they should contain information of value for the policy-setting process. If
those signals of market participants' expectations are blurred by extreme movements,
important information may be misread or lost.
Of course, some uncertainty is inevitable and quite manageable in the course of normal
policymaking. By virtue of its mandate, the Federal Reserve focuses on price stability,
interpreted to mean stability of consumer prices. Monetary policy does not aim at any
particular relative price, nor is the mandate thought to refer to prices beyond consumer
prices, such as those for assets. Ordinarily, however, asset prices are among the many factors
that central bankers assess when we evaluate present economic and financial conditions and
the outlook. And when asset prices exhibit large, systematic, and persistent deviations from
fundamentals, the implications of those deviations inevitably get more prominence. Clearly
central bankers would benefit from a better understanding of asset price movements-particularly more extreme movements--so that we do not mistakenly facilitate in some way
potentially harmful outcomes.
Liquidity and Asset Prices
Overly rapid monetary expansion, or excessive liquidity, has been named as a leading suspect
in some episodes of unsustainable movements in asset prices. Liquidity is not a precise
concept, however. Liquidity could be measured narrowly as central bank money, for
example, or more broadly to reflect the multiplier effects of the financial system; sometimes
it is measured instead by the level of policy interest rates. All these definitions and others
have been in play in the economics profession's analysis of the link between monetary
conditions and asset prices. What is meant by "excessive" is even less well defined. Some
commentators have taken a circular approach: If monetary conditions were comparatively
easy when asset prices experienced a significant swing, then liquidity must have been
"excessive."
A good place to start to unravel some of these issues is to look at the data. The results of
research at the Board and that of many others seeking to document a link between liquidity
and swings in asset prices has focused on growth rates of broad monetary aggregates and
measures of equity and house prices deflated by the price index for personal consumption
expenditures.1 Using these measures, the results differ significantly according to the type of
asset being studied. For equity prices, under various alternative specifications, the link
between the growth rate of liquidity and changes in real equity prices at frequencies beyond
very short term appears to be tenuous at best.2 To illustrate, the upper panel of figure 1 shows
a scatter plot of contemporaneous four-quarter growth rates of M3 and changes in broad
measures of equity prices for sixteen industrial countries during roughly the past twenty-five
years.3 As you can see, no obvious sign of a meaningful correlation at this frequency is
evident in this pattern. Indeed, the actual correlation is slightly negative. Most other
studies--such as the study by Bordo and Wheelock--using a variety of definitions and

more-rigorous techniques, support the same conclusion.4 The lack of a strong finding of any
positive medium- to longer-run relationship, of course, could be because equity prices are
quite volatile, making unconditional correlation difficult to identify. Perhaps, too,
more-refined measures of liquidity than those used in studies so far are needed to capture
possible effects on equity prices. So the effect of money growth on real equity prices is by no
means a closed question, and there certainly would be interest in whatever might come from
further research on this topic.
In contrast, the link between monetary growth, as measured by M3, and changes in real
house prices appears to be more definite. The bottom panel of figure 1 shows a similar scatter
plot for the same group of countries and periods as in the upper panel, but for changes in real
house prices. The two series exhibit a small positive correlation that is statistically significant.
Moreover, various tests have shown that the correlation is not just a recent phenomenon or
confined to a few countries; it is evident in varying degrees both over time and across our
sample of sixteen countries. Again, this finding is consistent with findings from a number of
other academic researchers. (I might add that the correlation with real house prices also holds
even if M3 is normalized by prices or gross domestic product. Negative correlation between
interest rates and house prices is, of course, not unexpected.)
To explore this relationship further, figure 2 provides some background on longer-term
movements in house prices in the United States, the United Kingdom, and Japan--three
countries where house price movements have been prominent.5 As the three panels show,
each country's movements in real house prices have experienced two or three cycles during
the past thirty-five years, usually with relatively long periods of gains followed by long
periods of decline. This suggests that one potentially useful way to explore further the
relationship between liquidity and asset prices is to examine movements in those two
variables in ten-year windows surrounding house price peaks. The solid line in figure 3 shows
the average behavior of the growth rate of M3 from twenty quarters before a peak in real
house prices until twenty quarters after the peak, where the average is taken across all the
cyclical episodes in our broad sample. The broken line in the chart is the log level of real
house prices indexed to zero in the peak year. As can be seen from the chart, on average the
growth rate of money increases fairly steadily until around two quarters before the peak in
real house prices and then drops fairly steadily for ten quarters afterward before recovering
somewhat. Although there are some variations, this pattern tends to occur in most countries'
episodes.6 Importantly, the connection between money growth and house prices does not
seem to vary much with the rate of macroeconomic expansion. This statement is underlined
by figure 4, which shows as an example actual house prices for the United Kingdom (the
broken line) and their forecasted values from an equation based on the growth rate of real
broad money and real long-term interest rates over more than twenty years (the solid line).
The close correspondence is apparent.
While these results are suggestive, correlation is by no means causality. Confirming that
variations in growth rates of liquidity (especially unusual changes in liquidity growth that
could be called excessive) systematically lead to wide swings in real asset prices requires
further theoretical investigation and more empirical support. That asset prices rise during a
period of monetary easing is not surprising, of course. But why growth of money sometimes
might cause housing prices to move more than other asset prices or, for that matter, than
goods prices is not clear. Indeed, some elements of causality run in the opposite direction,
clouding the underlying relationships. For instance, as the value of collateral rises during a
house price boom, the associated expansion of credit typically leads to increases in broad

money. The effect can be accentuated by the temporary parking in liquid accounts of the
proceeds from the more-frequent turnover and refinancings that often accompany a house
price boom.
Complicating the analysis further, a substantial list of third factors could drive both housing
prices and liquidity measures, producing co-movements that look like causality. A
productivity shock or a sharp decrease in energy prices, for example, could lead to general
economic expansion and rising asset prices while goods prices are not rising. This situation
might allow more liquid monetary conditions than would otherwise be the case.
Distinguishing the various forces in play obviously requires tools that are finer than simple
observations that both liquidity measures and assets prices are moving together.
Identification of Unsustainable Movements
The example cited above also should remind us that not all situations in which asset prices are
rising rapidly under seemingly easy monetary conditions are worrisome. Some are quite
benign and even signal a healthy economy. Accordingly, for policymakers who have to
confront these situations in real time, a fundamental challenge is identification. When asset
prices are moving in an unusual manner, is the movement unsustainable; does the pattern
arise from excessive liquidity in the market; and will policy be challenged by that
combination at some future date? Or are we observing a more complex process, perhaps less
aberrant and less prone to a troubling reversal?
The answers to these questions depend in part on the link between an asset's price and some
estimate of its "fundamental" value. Unfortunately, from the point of view of both the analyst
and the policymaker, the link between an asset's price and the structure of its return is hard to
pin down, as it typically embodies complex factors that are inherently difficult to measure,
such as expected future earnings, riskiness, and risk aversion. Consequently, for evaluating in
real time whether prices may be "off track" and, if so, by how much, we have to fall back on
more readily observable measures that, in principle at least, should bear some systematic
relationship to ideal measures and that can be assessed against historical experience. For
equities, a stock's price-earnings ratio is a standard benchmark for assessing valuation. In the
late 1990s, the price-earnings ratio for U.S. equities--especially in the high-tech area--soared
to record levels, and the so-called equity risk premium narrowed to a historical low. There
was a strong sense at the time that such elevated price levels were unusual, but there was no
uniform consensus regarding whether or not they were sustainable. All agreed, however, that
the pricing of assets, given profit expectations, was difficult. And even after we have seen a
major correction, our understanding of what drove that process and what the proper level
should have been--and should be now--still is unsettled.7
For housing, rent-to-price ratios and income-to-price ratios are commonly used measures to
assess valuation. Over the past several years, both measures have decreased sharply in many
countries, and they currently are well outside historical ranges in some countries. In 2004,
U.S. home prices increased 11.2 percent, their fastest pace since 1979, and right now, housing
prices in many markets in the United States are relatively high when judged by conventional
valuation measures.8 To know if housing is fairly valued requires assessing whether today's
valuations are consistent with unobservable future rents, interest rates, and returns--concepts
for which we have only rough proxies. However, in some markets the most prudent judgment
is that the growth of house prices will slow from the rapid pace experienced most recently.
Interpretation of Correlation: Other Fundamental Factors
The issue of identification becomes much more difficult in a changing environment. Some

patterns of asset price changes that are attributed to excess liquidity may arise, for example,
from financial innovation and other structural changes.9 But mapping such changes into asset
price movements to control for such factors is difficult. For example, the rise in house prices
in the United Kingdom in the late 1980s was thought at the time to relate importantly to the
liberalization of U.K. banking laws several years earlier and, therefore, likely to be
sustainable. As it turned out, the run-up ended fairly soon and was followed by a steep
decline. The inability to more accurately gauge the effects on asset prices conferred (or not)
by earlier structural changes likely contributed to the inaccurate expectation that they would
last longer. In Sweden, the large and swift increases in property prices in the 1980s also
related in part to the earlier liberalization of domestic banking laws and consequent easier
lending practices. The tax reform of 1990, which among other things made the tax treatment
of mortgage interest rates in Sweden considerably less favorable, contributed to a subsequent
drop in property prices that ultimately severely stressed banks' balance sheets, an experience
that again highlighted the potential impact of such structural factors on asset price
movements.
Controlling for cyclical effects on both liquidity and real asset prices is basic, of course, in
any empirical assessment of how they may be linked. But some observers have conjectured
that, beyond conventional cyclical patterns in a benign environment with low-inflation and
strong real growth such as we have had in recent years, investors' preferences and behaviors
may change qualitatively in ways that are not captured well by models based on historical
patterns. Faced with cumulating wealth and lower nominal returns, investors may develop a
distinctly greater tolerance for risk that results in aggressive "search for yield" behavior. This
behavior may engender, it is argued, a tendency for unusual run-ups in some asset prices. If
so, a concern is that changes in the underlying conditions that fostered this pattern or a policy
misstep could cause a quick reversion to the historical norm. The policy community has been
on the lookout for such patterns of "search for yield" during the latest cycle of low rates and
tightening.10
Others have argued that in certain circumstances, when special factors may be preventing
inflationary pressures from showing through to consumer prices, increases in asset prices
might serve as an early, more visible warning that liquidity is excessive. It has been asserted,
for example, that the strength of the yen in the late 1980s stifled Japanese consumer price
inflation and contributed to an easier policy stance by the Bank of Japan.11 The fact that
resulting liquidity was greater than would have been ideal was most apparent (unfortunately,
more so in retrospect) in Japan's booming asset prices. A sharp (but temporary) boost in
productivity or disruption of exchange rate pass-through behavior could have similar masking
effects. But whether, in general, asset prices could provide reliable signals of suppressed but
impending general inflation is a complex matter, and elevating asset prices to a more
prominent role in the policy process is not without a number of potential pitfalls.
Among other complications is the possibility that financial globalization may be changing the
links between liquidity and asset prices. Movements in asset prices across countries now
appear to be more synchronized. This synchronization could arise in a number of ways.
National business cycles and policy responses may be moving more in tandem just because
national economies have become more closely integrated through trade and investment,
producing in turn a greater synchronization in asset markets. Global shocks (for example,
from oil prices and geopolitical risk factors) that produce broadly similar effects on most
economies may have become more prevalent and may tend to dominate idiosyncratic
national shocks. But it also is quite possible that greater international diversification of

portfolios now allows developments affecting assets in one country to spill over into markets
of others--both at the level of particular industries and more broadly. If synchronization of
asset price movements comes about mainly in this way, the suggestion is that excess liquidity
in one country could move asset prices in another, perhaps significantly, even if liquidity was
well contained in the latter.12
In the somewhat longer run, patterns of aggregate saving--influenced, for example, by
demographic developments--may also affect the path of real interest rates and, in turn, prices
of assets, again complicating interpretation of co-movements. For instance, an increase in
savings as a growing share of the population nears retirement may reduce real rates and raise
asset prices. Patterns of immigration that affect the population's demographic profile, too, can
affect asset prices. In the United States, we have seen some of these effects in certain
segments of the housing market.
Conclusions
In summary, although excess liquidity has been cited as a source of general asset price
instability, the support for this conclusion is mixed, at best. We do find a positive correlation
between growth rates of real house prices and M3, but the correlation does not seem to hold
for real asset prices more generally--including, in particular, equities. In this talk, I have
suggested that we are only at the beginning of an understanding of some of these
relationships. Even if an underlying causal link exists between some real asset prices and
liquidity, many additional factors may be influencing what we see, with potential for
misleading us in interpreting simple associations or correlations. The problem obviously is
complex. As a start, however, we need a better understanding of how asset prices are
determined that can be translated into guidance for a policy process that uses real-time
variables. To borrow a turn of phrase cited often in the physical sciences, theory tends to
"explain a complex visible, with a simple invisible."13 In the realm of policy, of course, we
need to work with simple, but reliable visibles--a requirement that makes this task all the
more challenging. For that reason, I have been pleased to join this group of distinguished
economists this evening.
Appendix
Countries in the dataset and the date for the beginning of the broad money series used for
each country are as follows:
Country

First data point
for broad money

Australia

1970

Belgium

1996

Canada

1970

Denmark

1993

Finland

1990

France

1980

Germany

1980

Japan

1980

Netherlands

1982

New Zealand

1988

Norway

1970

Spain

1997

Sweden

1985

Switzerland

1985

United Kingdom

1982

United States

1970

Residential real estate and equity index data cover the period 1970-2004 for all countries
except Spain, for which the coverage begins in 1971.
Figures

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Footnotes
1. I wish to thank Robert Martin, Alain Chaboud, Jon Faust, and Brian Doyle of the Board
staff for research support. Return to text
2. Various studies have found that stock prices do exhibit an immediate reaction to monetary
policy surprises, not unlike their responses to other macroeconomic surprises, for example,
Ben S. Bernanke and Kenneth Kuttner (2005), "What Explains the Stock Market's Reaction
to Federal Reserve Policy?," Journal of Finance, vol. 60, 1221-57. Return to text
3. Data on residential real estate and equity prices are from the Bank for International
Settlements and, for most countries, are quarterly. M3 data are derived from national sources;
the length of the series on M3 varies across countries. The list of countries covered and the
relevant periods are provided in the appendix. Return to text
4. Michael D. Bordo and David C. Wheelock (2004), "Monetary Policy and Asset Prices: A
Look Back at Past U.S. Stock Market Booms," NBER Working Paper 10704. Return to text
5. House prices in other industrial countries have shown similar, but generally more
modulated, swings. Return to text
6. The correlation between real house prices and money growth in Japan was close to zero
during the deflationary 1990s. Return to text

7. For further details on the difficulty of identifying unsustainable movements in asset prices,
see Refet S. Gurkaynak (2005), "Econometric Tests of Asset Price Bubbles: Taking Stock,"
(Finance and Economic Discussion Series) working paper 2005-04. Return to text
8. The source of the data is the Office of Federal Housing Enterprise Oversight. The OFHEO
index is based on repeat sales prices derived from mortgage acquisitions on conforming loans.
Return to text
9. See, for example, Franklin Allen and Douglas Gale (2000), "Bubbles and Crises,"
Economic Journal, vol. 110, pp. 236-56. Return to text
10. For example, see my statement as Chairman of the Financial Stability Forum to the
International Monetary and Financial Committee, April 16, 2005, Washington, D.C., and
International Monetary Fund Global Financial Stability Report, 2005. Return to text
11. See, for example, Takatoshi Ito and Frederic S. Mishkin (2004), "Two Decades of
Japanese Monetary Policy and the Deflation Problem," NBER working paper 10878. Return
to text
12. This argument obviously applies best to markets such as those for equities where crossholdings and international diversification are comparatively well developed. An IMF research
paper has found evidence of liquidity spillovers and that an increase in aggregate G-7
liquidity is "consistent with" an increase in G-7 real stock returns (Klaas Baks and Charles
Kramer (1999), "Global Liquidity and Asset Prices: Measurement, Implications, and
Spillovers," IMF working paper 99/168). Return to text
13. The origin of the remark is generally attributed to French scientist Jean Baptiste Perrin in
his Nobel Lecture, given when accepting the 1926 Nobel Prize in physics. Return to text
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Last update: May 27, 2005