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For release on delivery
10:15 a.m. PST (1:15 p.m. EST)
January 3, 2004

Risk and Uncertainty in Monetary Policy
Remarks by
Alan Greenspan
Chairman
Board of Governors of the Federal Reserve System
at the
American Economic Association
San Diego, California
January 3, 2004

This morning I plan to sketch the key developments of the past decade and a half of
monetary policy in the United States from the perspective of someone who has been in the policy
trenches. I will offer some conclusions about what I believe has been learned thus far, though I
suspect, as is so often the case, the passing of time, further study, and reflection will deepen our
understanding of these developments. This is a personal statement; I am not speaking for my
current colleagues on the Federal Open Market Committee (FOMC) or the many others with
whom I have served over these many years.1
***
The tightening of monetary policy by the Federal Reserve in 1979, then led by my
predecessor Paul Volcker, ultimately broke the back of price acceleration in the United States,
ushering in a two-decade long decline in inflation that eventually brought us to the current state
of price stability.
The fall in inflation over this period has been global in scope, and arguably beyond the
expectations of even the most optimistic inflation fighters. I have little doubt that an unrelenting
focus of monetary policy on achieving price stability has been the principal contributor to
disinflation. Indeed, the notion, advanced by Milton Friedman more than thirty years ago, that
inflation is everywhere and always a monetary phenomenon is no longer a controversial
proposition in the profession. But the size and geographic extent of the decline in inflation raises
the question of whether other forces have been at work as well.
I am increasingly of the view that, at a minimum, monetary policy in the last two decades
has been operating in an environment particularly conducive to the pursuit of price stability. The
principal features of this environment included (1) increased political support for stable prices,
which was the consequence of, and reaction to, the unprecedented peacetime inflation in the

1970s, (2) globalization, which unleashed powerful new forces of competition, and (3) an
acceleration of productivity, which at least for a time held down cost pressures.
I believe we at the Fed, to our credit, did gradually come to recognize the structural
economic changes that we were living through and accordingly altered our understanding of the
key parameters of the economic system and our policy stance. The central banks of other
industrialized countries have grappled with many of the same issues.
But as we lived through it, there was much uncertainty about the evolving structure of the
economy and about the influence of monetary policy. Despite those uncertainties, the trauma of
the 1970s was still so vivid throughout the 1980s that preventing a return to accelerating prices
was the unvarying focus of our efforts during those years.
In recognition of the lag in monetary policy's impact on economic activity, a preemptive
response to the potential for building inflationary pressures was made an important feature of
policy. As a consequence, this approach elevated forecasting to an even more prominent place in
policy deliberations.
* **
After an almost uninterrupted stint of easing from the summer of 1984 through the spring
of 1987, the Fed again began to lean against increasing inflationary pressures, which were in part
the indirect result of rapidly rising stock prices. We had recognized the risk of an adverse
reaction in a stock market that had recently experienced a steep run-up--indeed, we actively
engaged in contingency planning against that possibility.
In the event, the crash in October 1987 was far more traumatic than any of the possible
scenarios we had identified. Previous planning was only marginally useful in that episode. We
operated essentially in a crisis mode, responding with an immediate and massive injection of

liquidity to help stabilize highly volatile financial markets. However, most of our stabilization
efforts were directed at keeping the payments system functioning and markets open.

The

concern over the possible fallout on economic activity from so sharp a stock price decline kept
us easing into early 1988. But the economy weathered that shock reasonably well, and our
easing extended perhaps longer than hindsight has indicated was necessary.
That period was followed by a preemptive tightening that brought the federal funds rate
close to 10 percent by early 1989. In the summer of that year, we sensed enough softening of
activity to warrant beginning a series of rate reductions. However, the weakening of demand
already under way, some pullback of credit by lenders, and the spike in oil prices associated with
Iraq's invasion of Kuwait were sufficient to produce a marked contraction of activity in the fall
of 1990. But perhaps aided by our preemptive action, the recession was, to then, the mildest in
postwar history.
However, the recovery also was more modest than usual, in large measure because of the
notable financial "headwinds" that confronted businesses. Those headwinds were primarily
generated by the constriction of credit in response to major losses at banks, associated with
real-estate and foreign lending, coupled with a crisis in the savings and loan industry that had its
origins in a serious maturity mismatch as interest rates rose. With their access to managed funds
threatened and the quality of their loan portfolio—and hence their capital—uncertain, these
depositories were most reluctant to lend.
Policy eased gradually but persistently to counter the effects of these developments, with
the funds rate falling to 3 percent by September 1992, its lowest level since the early 1960s. The
uptilt to the term structure of interest rates in a generally low interest rate environment restored
bank profitability and, eventually, bank capital. The credit crunch slowly lifted.

By early 1994, as the headwinds of financial restraint abated, it became clear that
underlying price pressures were again building. If we had left those pressures unchecked, we
would have put at risk some of the hard-won gains that had been achieved over the preceding
decade and a half. So, starting from a real federal funds rate that was close to zero, a preemptive
tightening was initiated. The resulting rise in the funds rate of 300 basis points over twelve
months apparently defused those nascent inflationary pressures.
Though economic activity hesitated in early 1995, it soon steadied, confirming the
achievement of a historically elusive soft landing.

The success of that period set up two

powerful expectations that were to influence developments over the subsequent decade. One
was the expectation that inflation could be controlled over the business cycle and that price
stability was an achievable objective. The second expectation, in part a consequence of more
stable inflation, was that overall economic volatility had been reduced and would likely remain
lower than it had previously.
Of course, these new developments brought new challenges. In particular, the prospect
that a necessary cyclical adjustment was now behind us fostered increasing levels of optimism,
which were manifested in a fall in bond risk spreads and a rise in stock prices. The associated
decline in the cost of equity capital further spurred already developing increases in capital
investment and productivity growth, both of which broadened impressively in the latter part of
the 1990s.
The rise in structural productivity growth was not obvious in the official data on gross
product per hour worked until later in the decade, but precursors had emerged earlier. The
pickup in new bookings and order backlogs for high-tech capital goods in 1993 seemed
incongruous given the sluggish economic environment at the time. Plant managers apparently

were reacting to what they perceived to be elevated prospective rates of return on the newer
technologies, a judgment that was confirmed as orders and profits continued to increase through
1994 and 1995. Moreover, even though hourly labor compensation and profit margins were
rising, prices were being contained, implying increasing growth in output per hour.2
As a consequence of the improving trend in structural productivity growth that was
apparent from 1995 forward, we at the Fed were able to be much more accommodative to the
rise in economic growth than our past experiences would have deemed prudent. We were
motivated, in part, by the view that the evident structural economic changes rendered suspect, at
best, the prevailing notion in the early 1990s of an elevated and reasonably stable NAIRU.
Those views were reinforced as inflation continued to fall in the context of a declining
unemployment rate that by 2000 had dipped below 4 percent in the United States for the first
time in three decades.
Notions that prevailed for a time in the 1970s and early 1980s that even high single-digit
inflation did not measurably impede economic growth were gradually abandoned as the evidence
of significant benefits of low inflation became increasingly persuasive. Moreover, the variance
of GDP growth markedly lessened as inflation tumbled from its double-digit high in the early
1980s. To preserve these benefits, we engaged in our most recent preemptive tightening in early
1999 that brought the funds rate to 6-1/2 percent by May 2000.
Our goal of price stability was achieved by most analysts' definition by mid-2003.
Unstinting and largely preemptive efforts over two decades had finally paid off. Throughout the
period, a key objective has been to ensure that our response to incipient changes in inflation was
forceful enough. As John Taylor has emphasized, in the face of an incipient increase in

inflation, nominal interest rates must move up more than one-for-one.3
***
Perhaps the greatest irony of the past decade is that the gradually unfolding success
against inflation may well have contributed to the stock price bubble of the latter part of the
1990s.4

Looking back on those years, it is evident that technology-driven increases in

productivity growth imparted significant upward momentum to expectations of earnings growth
and, accordingly, to stock

prices.5

At the same time, an environment of increasing

macroeconomic stability reduced perceptions of risk. In any event, Fed policymakers were
confronted with forces that none of us had previously encountered. Aside from the then-recent
experience of Japan, only remote historical episodes gave us clues to the appropriate stance for
policy under such conditions. The sharp rise in stock prices and their subsequent fall were, thus,
an especial challenge to the Federal Reserve.
It is far from obvious that bubbles, even if identified early, can be preempted at lower
cost than a substantial economic contraction and possible financial destabilization—the very
outcomes we would be seeking to avoid.
In fact, our experience over the past two decades suggests that a moderate monetary
tightening that deflates stock prices without substantial effect on economic activity has often
been associated with subsequent increases in the level of stock prices.6 Arguably, markets that
pass that type of stress test are presumed particularly resilient. The notion that a well-timed
incremental tightening could have been calibrated to prevent the late 1990s bubble while
preserving economic stability is almost surely an illusion.7
Instead of trying to contain a putative bubble by drastic actions with largely

unpredictable consequences, we chose, as we noted in our mid-1999 congressional testimony, to
focus on policies "to mitigate the fallout when it occurs and, hopefully, ease the transition to the
next expansion."8
***
During 2001, in the aftermath of the bursting of the bubble and the acts of terrorism in
September 2001, the federal funds rate was lowered 4-3/4 percentage points. Subsequently,
another 75 basis points were pared, bringing the rate by June 2003 to its current 1 percent, the
lowest level in 45 years. We were able to be unusually aggressive in the initial stages of the
recession of 2001 because both inflation and inflation expectations were low and stable. We
thought we needed to be, and could be, forceful in 2002 and 2003 as well because, with demand
weak, inflation risks had become two-sided for the first time in forty years.
There appears to be enough evidence, at least tentatively, to conclude that our strategy of
addressing the bubble's consequences rather than the bubble itself has been successful. Despite
the stock market plunge, terrorist attacks, corporate scandals, and wars in Afghanistan and Iraq,
we experienced an exceptionally mild recession—even milder than that of a decade earlier. As I
discuss later, much of the ability of the U.S. economy to absorb these sequences of shocks
resulted from notably improved structural flexibility. But highly aggressive monetary ease was
doubtless also a significant contributor to stability.9
***
The Federal Reserve's experiences over the past two decades make it clear that
uncertainty is not just a pervasive feature of the monetary policy landscape; it is the defining
characteristic of that landscape. The term "uncertainty" is meant here to encompass both

"Knightian uncertainty," in which the probability distribution of outcomes is unknown, and
"risk," in which uncertainty of outcomes is delimited by a known probability distribution. In
practice, one is never quite sure what type of uncertainty one is dealing with in real time, and it
may be best to think of a continuum ranging from well-defined risks to the truly unknown.
As a consequence, the conduct of monetary policy in the United States has come to
involve, at its core, crucial elements of risk management.

This conceptual framework

emphasizes understanding as much as possible the many sources of risk and uncertainty that
policymakers face, quantifying those risks when possible, and assessing the costs associated with
each of the risks. In essence, the risk management approach to monetary policymaking is an
application of Bayesian decisionmaking.
This framework also entails devising, in light of those risks, a strategy for policy directed
at maximizing the probabilities of achieving over time our goals of price stability and the
maximum sustainable economic growth that we associate with it. In designing strategies to meet
our policy objectives, we have drawn on the work of analysts, both inside and outside the Fed,
who over the past half century have devoted much effort to improving our understanding of the
economy and its monetary transmission mechanism. A critical result has been the identification
of a relatively small set of key relationships that, taken together, provide a useful approximation
of our economy's dynamics. Such an approximation underlies the statistical models that we at
the Federal Reserve employ to assess the likely influence of our policy decisions.
However, despite extensive efforts to capture and quantify what we perceive as the key
macroeconomic relationships, our knowledge about many of the important linkages is far from
complete and, in all likelihood, will always remain so. Every model, no matter how detailed or
how well designed, conceptually and empirically, is a vastly simplified representation of the

world that we experience with all its intricacies on a day-to-day basis.
Given our inevitably incomplete knowledge about key structural aspects of an
ever-changing economy and the sometimes asymmetric costs or benefits of particular outcomes,
a central bank needs to consider not only the most likely future path for the economy but also the
distribution of possible outcomes about that path. The decisionmakers then need to reach a
judgment about the probabilities, costs, and benefits of the various possible outcomes under
alternative choices for policy.
A policy action that is calculated to be optimal based on a simulation of one particular
model may not, in fact, be optimal once the full extent of the risks surrounding the most likely
path is taken into account.

In general, different policies will exhibit different degrees of

robustness with respect to the true underlying structure of the economy.
For example, policy A might be judged as best advancing the policymakers' objectives,
conditional on a particular model of the economy, but might also be seen as having relatively
severe adverse consequences if the true structure of the economy turns out to be other than the
one assumed. On the other hand, policy B might be somewhat less effective in advancing the
policy objectives under the assumed baseline model but might be relatively benign in the event
that the structure of the economy turns out to differ from the baseline. A year ago, these
considerations inclined Federal Reserve policymakers toward an easier stance of policy aimed at
limiting the risk of deflation even though baseline forecasts from most conventional models at
that time did not project deflation; that is, we chose a policy that, in a world of perfect certainty,
would have been judged to be too loose.
As this episode illustrates, policy practitioners operating under a risk-management
paradigm may, at times, be led to undertake actions intended to provide insurance against

especially adverse outcomes. Following the Russian debt default in the autumn of 1998, for
example, the FOMC eased policy despite our perception that the economy was expanding at a
satisfactory pace and that, even without a policy initiative, it was likely to continue doing so. 1 0
We eased policy because we were concerned about the low-probability risk that the default
might trigger events that would severely disrupt domestic and international financial markets,
with outsized adverse feedback to the performance of the U.S. economy.
The product of a low-probability event and a potentially severe outcome was judged a
more serious threat to economic performance than the higher inflation that might ensue in the
more probable scenario. That possibility of higher inflation caused us little concern at the time,
largely because increased productivity growth was resulting in only limited increases in unit
labor costs and heightened competition, driven by globalization, was thwarting employers'
ability to pass through those limited cost increases into prices. Given the potential consequences
of the Russian default, the benefits of the unusual policy action were judged to outweigh its
costs.
Such a cost-benefit analysis is an ongoing part of monetary policy decisionmaking and
causes us to tip more toward monetary ease when a contractionary event, such as the Russian
default, seems especially likely or the costs associated with it seem especially high.
The 1998 liquidity crisis and the crises associated with the stock market crash of 1987
and the terrorism of September 2001 prompted the type of massive ease that has been the historic
mandate of a central bank. Such crises are precipitated by the efforts of market participants to
convert illiquid assets into cash.

When confronted with uncertainty, especially Knightian

uncertainty, human beings invariably attempt to disengage from medium to long-term
commitments in favor of safety and

liquidity.

Because economies, of necessity, are net

long—that is, have net real assets—attempts to flee these assets cause prices of equity assets to
fall, in some cases dramatically. In the crisis that emerged in the autumn of 1998, pressures
extended beyond equity markets. Credit-risk spreads widened materially and investors put a
particularly high value on liquidity, as evidenced by the extraordinarily wide yield gaps that
emerged between on-the-run and off-the-run U.S. Treasuries.
The immediate response on the part of the central bank to such financial implosions must
be to inject large quantities ofliqudity—

or

as Walter Bagehot put it, describing such policies of

the Bank of England more than a century ago, in a panic the Bank should lend at very high rates
of interest "to all that bring good securities quickly, freely, and readily." 1 1 This was perhaps an
early articulation of a crisis risk management policy for central bank.
• * *

The economic world in which we function is best described by a structure whose
parameters are continuously changing. The channels of monetary policy, consequently, are
changing in tandem. An ongoing challenge for the Federal Reserve-indeed, for any central
bank—is to operate in a way that does not depend on a fixed economic structure based on
historically average coefficients. We often fit simple models only because we cannot estimate a
continuously changing set of parameters without vastly more observations than are currently
available to us. Moreover, we recognize that the simple linear functions underlying most of our
econometric structures may not hold outside the range in which adequate economic observations
exist. For example, it is difficult to have much confidence in the ability of models fit to the data
of the moderate inflations of the postwar period to accurately predict what the behavior of the
economy would be in an environment of aggregate price deflation.
In pursuing a risk-management approach to policy, we must confront the fact that only a

limited number of risks can be quantified with any confidence.

And even these risks are

generally quantifiable only if we accept the assumption that the future will, at least in some
important respects, resemble the past. Policymakers often have to act, or choose not to act, even
though we may not fully understand the full range of possible outcomes, let alone each possible
outcome's likelihood. As a result, risk management often involves significant judgment as we
evaluate the risks of different events and the probability that our actions will alter those risks.
For such judgment, policymakers have needed to reach beyond models to
broader —

though

less mathematically precise-hypotheses about how the world works.

example, inferences about how market participants and, hence, the economy might respond to a
monetary policy initiative may need to be drawn from evidence about past behavior during a
period only roughly comparable to the current situation.
Some

critics

have

argued

that

such

an

approach

to

policy

undisciplined—judgmental, seemingly discretionary, and difficult to explain.

is

too

The Federal

Reserve, they conclude, should attempt to be more formal in its operations by tying its actions
solely, or in the weaker paradigm, largely, to the prescriptions of a simple policy rule. Indeed,
rules that relate the setting of the federal funds rate to the deviations of output and inflation from
their respective targets, in some configurations, do seem to capture the broad contours of what
we did over the past decade and a half. And the prescriptions of formal rules can, in fact, serve
as helpful adjuncts to policy, as many of the proponents of these rules have suggested. But at
crucial points, like those in our recent policyhistory—

the

stock market crash of 1987, the crises

of 1997-98, and the events that followed September 2001-simple rules will be inadequate as
either descriptions or prescriptions for policy. Moreover, such rules suffer from much of the
same fixed-coefficient difficulties we have with our large-scale models.

For

To be sure, sensible policymaking can be accomplished only with the aid of a rigorous
analytic structure.

A rule does provide a benchmark against which to assess emerging

developments. However, any rule capable of encompassing every possible contingency would
lose a key aspect of its attractiveness: simplicity. On the other hand, no simple rule could
possibly describe the policy action to be taken in every contingency and thus provide a
satisfactory substitute for an approach based on the principles of risk management.
As I indicated earlier, policy has worked off a risk-management paradigm in which the
risk and cost-benefit analyses depend on forecasts of probabilities developed from large
macromodels, numerous submodels, and judgments based on less mathematically precise
regimens. Such judgments, by their nature, are based on bits and pieces of history that cannot
formally be associated with an analysis of variance.
Yet, there is information in those bits and pieces. For example, while we have been
unable to readily construct a variable that captures the apparent increased degree of flexibility in
the United States or the global economy, there has been too much circumstantial evidence of this
critically important trend to ignore its existence. Increased flexibility is a likely source of
changing structural coefficients.
Our problem is not, as is sometimes alleged, the complexity of our policymaking process,
but the far greater complexity of a world economy whose underlying linkages appear to be
continuously evolving. Our response to that continuous evolution has been disciplined by the
Bayesian type of decisionmaking in which we have engaged.
** *
While all, no doubt, would prefer that it were otherwise, there is no way to dismiss what
has to be obvious to every monetary policymaker: The success of monetary policy depends

importantly on the quality of forecasting. The ability to gauge risks implies some judgment
about how current economic imbalances will ultimately play out.
Thus, both econometric and qualitative models need to be continually tested. The first
signs that a relationship may have changed is usually the emergence of events that seem
inconsistent with our hypotheses of the way the economic world is supposed to behave. The
anomalous rise in high-tech capital goods orders in 1993, to which I alluded earlier, is one such
example. The credit crunch of the early 1990s is another.

The emergence of inflation targeting in recent years is an interesting development in this
regard.

As practiced, it emphasizes forecasts, but within a more rule-like structure that skews

monetary policy toward inflation containment as the primary goal. Indeed, its early applications
were in high-inflation countries where discretionary monetary policy fell into disrepute.
Inflation targeting often originated as a fairly simple structure concentrating solely on
inflation outcomes, but it has evolved into more-discretionary forms requiring complex
judgments for implementation. Indeed, this evolution has gone so far that the actual practice of
monetary policy by inflation-targeting central banks now closely resembles the practice of those
central banks, such as the European Central Bank, the Bank of Japan, and the Federal Reserve,
that have not chosen to adopt that paradigm.
In practice, most central banks, at least those not bound by an exchange rate peg, behave
in roughly the same way. They seek price stability as their long-term goal and, accounting for
the lag in monetary policy, calibrate the setting of the policy rate accordingly. Central banks
generally appear to have embraced a common model of the channels through which monetary
policy functions, although the specifics and emphasis given to those channels vary according to

our particular circumstances. All banks ease when economic conditions ease and tighten when
economic conditions tighten, even if in differing degrees, regardless of whether they are guided
by formal or informal inflation targets.
As yet unresolved is whether the mere announcement that a central bank intends to
engage in inflation targeting increases the credibility of the central bank's inclination to maintain
price stability and, hence, assists in the anchoring of inflation expectations.

The Bank of

England's recent experiences may be encouraging in this regard. But, presumably, we will not
know for sure the significance of formal inflation targeting as a tool until the world economy is
subjected to shocks of sufficient magnitude to assess the differential performance of those who
do not employ formally announced inflation targets. To date, inflation has fallen for formal
targeters, but it has fallen for others as well.
* **
Under the rubric of risk management are a number of specific issues that we at the Fed
had to address over the past decade and a half and that will likely resurface to confront future
monetary policymakers.
Most prominent is the appropriate role of asset prices in policy. In addition to the
narrower issue of product price stability, asset prices will remain high on the research agenda of
central banks for years to come. As the ratios of gross liabilities and gross assets to GDP
continue to rise, owing to expanding domestic and international financial intermediation, the
visibility of asset prices relative to product prices will itself rise. There is little dispute that the
prices of stocks, bonds, homes, real estate, and exchange rates affect GDP. But most central
banks have chosen, at least to date, not to view asset prices as targets of policy, but as economic
variables to be considered through the prism of the policy's ultimate objective.

* * *

As the transcripts of FOMC meetings attest, making monetary policy is an especially
humbling activity. In hindsight, the paths of inflation, real output, stock prices and exchange
rates may have seemed preordained, but no such insight existed as we experienced it at the time.
In fact, uncertainty characterized virtually every meeting, and, as the transcripts show, our ability
to anticipate was limited. From time to time the FOMC made decisions, some to move and some
not to move, that we came to regret.
Yet, during the last quarter century, policymakers managed to defuse dangerous
inflationary forces and dealt with the consequences of a stock market crash, a large asset price
bubble, and a series of liquidity crises. These events did not distract us from the pursuit and
eventual achievement of price stability and the greater economic stability that goes with it.
As we confront the many unspecifiable dangers that lie ahead, the marked improvement
in the degree of flexibility and resilience exhibited by our economy in recent years should afford
us considerable comfort.12 Assuming that it will persist, the trend toward increased flexibility
implies that an ever-greater part of the resolution of economic imbalances will occur through the
actions of business firms and households. Less will be required from the risk-laden initiatives of
monetary policymakers.
Each generation of policymakers has had to grapple with a changing portfolio of
problems. So while we eagerly draw on the experiences of our predecessors, we can be assured
that we will confront different problems in the future. The innovative technologies that have
helped us reap enormous efficiencies will doubtless present us with challenges that we cannot
currently anticipate.
We were fortunate, as I pointed out in my opening remarks, to have worked in a

particularly favorable structural and political environment. But we trust that monetary policy has
meaningfully contributed to the impressive performance of our economy in recent decades.

1.

I, nonetheless, wish to thank my colleagues David Stockton, David Wilcox, Don Kohn, Ben

Bernanke, and John Taylor, for their many suggestions and reminiscences.
2.

That growth was showing through in gross income per hour. An increasingly negative

statistical discrepancy was masking the rise in productivity as measured by the official data that
relied on gross product per hour. As I indicated in the fall of 1994, "we are observing . . . [an]
opening up of margins . . . But unit labor costs apparently have been so well contained by
productivity gains at this stage that cost pressures have not flowed into final goods prices."
(FOMC transcripts, September 27,1994, pg. 37)
3.

See, for example, "A Half-Century of Changes in Monetary Policy," John B. Taylor,

remarks delivered at the conference in honor of Milton Friedman, November 8, 2002, pp 9-10,
manuscript, Department of the Treasury.
4.

It is notable, that in the United States, surges in price-earnings ratios, a presumed essential

characteristic of an equity price bubble, are not observed with elevated inflation expectations.
5.

But, as the Federal Reserve indicated in congressional testimony in July 1999, "...

productivity acceleration does not ensure that equity prices are not overextended. There can be
little doubt that if the nation's productivity growth has stepped up, the level of profits and their
future potential would be elevated. That prospect has supported higher stock prices. The danger
is that in these circumstances, an unwarranted, perhaps euphoric, extension of recent
developments can drive equity prices to levels that are unsupportable even if risks in the future
become relatively small.

Such straying above fundamentals could create problems for our

economy when the inevitable adjustment occurs." Testimony of Alan Greenspan before the
Committee on Banking and Financial Services, U.S. House of Representatives, July 22,1999.

6.

For example, stock prices rose following the completion of the more than 300 basis point

rise in the federal funds rate in the twelve months ending in February 1989. And during the year
beginning in February 1994, when the Federal Reserve again raised the federal funds target 300
basis points, stock prices initially flattened.

But as soon as that round of tightening was

completed, prices resumed their marked upward advance. From mid-1999 through May 2000,
the federal funds rate was raised 150 basis points. However, equity price increases were largely
undeterred during that period despite what now, in retrospect, was the exhausted tail of a bull
market. Stock prices peaked in March 2000, but the market basically moved sideways until
September of that year.
Such data suggest that nothing short of a sharp increase in short-term rates that engenders a
significant economic retrenchment with all its attendant risks is sufficient to check a nascent
bubble. Certainly, 300 basis points proved inadequate to even dent stock prices in 1994.
7.

Some have asserted that the Federal Reserve can deflate a stock-price bubble—rather

painlessly~by boosting margin requirements.

The evidence suggests otherwise.

First, the

amount of margin debt is small, having never amounted to more than about 1-3/4 percent of the
market value of equities; moreover, even this figure overstates the amount of margin debt used to
purchase stock, as such debt also finances short sales of equity and transactions in non-equity
securities.

Second, investors need not rely on margin debt to take a leveraged position in

equities. They can borrow from other sources to buy stock. Or, they can purchase options,
which will affect stock prices given the linkages across markets.
Thus, not surprisingly, the preponderance of research suggests that changes in margins are
not an effective tool for reducing stock market volatility. It is possible that margin requirements
inhibit very small investors whose access to other forms of credit is limited. If so, the only effect

of increasing margin requirements is to price out of the market the very small investor without
addressing the broader issue of stock price bubbles.
If a change in margin requirements were taken by investors as a signal that the central bank
would soon tighten monetary policy enough to burst a bubble, then there might be the
appearance of a causal effect. But it is the prospect of monetary policy action, not the margin
increase, that should be viewed as the trigger.

In a similar manner, history tells us that

"jawboning" asset markets will be ineffective unless backed by action.
8.

Op. cit.

9.

Some have argued that, as a consequence of the 1995-2000 speculative episode, long-term

imbalances remain, having been only partly addressed since early 2001, the peak of the
post-bubble business cycle. For example, large residues of household and external debt are
perceived as barriers to future growth.

But in the past, imbalances that led to business

contractions were rarely fully reversed before the subsequent economic

upturn began.

Presumably they were fully reversed in later periods, or they continued to fester, but not by
enough to halt economic growth.
Even if imbalances still persist in our current environment, the business decline that began
in March 2001 came to an end in November of that year, according to the National Bureau of
Economic Research. We experienced tepid recovery until the second half of last year, when
GDP accelerated considerably. Hence, when the next recession arrives, as it inevitably will, it
will be a stretch to attribute it to speculative imbalances of many years earlier.
10. See minutes of the FOMC meeting of September 29,1998.
11. Walter Bagehot, Lombard Street: A Description of the Money Market, (Orion Editions,
1873) p. 85.

12. See testimony of Alan Greenspan before the Committee on Banking, Housing, and Urban
Affairs, U.S. Senate, February 11, 2003.