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For release on delivery
8:00 a.m. MDT (10:00 a.m. EDT)
August 30, 2002

Opening Remarks of
Alan Greenspan
Chairman
Board of Governors of the Federal Reserve System
at
a symposium sponsored by the
Federal Reserve Bank of Kansas City
Jackson Hole, Wyoming
August 30, 2002

Over the past two decades we have witnessed a remarkable turnaround in the
U.S. economy. The aftermath of the Vietnam War and a series of oil shocks had left the
United States with high inflation, lackluster productivity growth, and a declining competitive
position in international markets.
But rather than accept the role of a once-great, but diminishing economic force, for
reasons that will doubtless be debated for years to come, we resurrected the dynamism of
previous generations of Americans. A wave of innovation across a broad range of technologies,
combined with considerable deregulation and a further lowering of barriers to trade, fostered a
pronounced expansion of competition and creative destruction.
The result through the 1990s of all this seeming-heightened instability for individual
businesses, somewhat surprisingly, was an apparent reduction in the volatility of output and in
the frequency and amplitude of business cycles for the macroeconomy. While the empirical
evidence on the importance of changes in the magnitude of the shocks hitting our economy
remains ambiguous, it does appear that shocks are more readily absorbed than in decades past.
The massive drop in equity wealth over the past two years, the sharp decline in capital
investment, and the tragic events of September 11 might reasonably have been expected to
produce an immediate severe contraction in the U.S. economy. But this did not occur.
Economic imbalances in recent years apparently have been addressed more expeditiously and
effectively than in the past, aided importantly by the more widespread availability and more
intensive use of real-time information.
But faster adjustments imply a greater volatility in expected corporate earnings. Although
direct estimates of investors' expectations for earnings are not readily available, indirect evidence

-2does seem to support an increased volatility in those expectations. Securities analysts'
expectations for long-term earnings growth, an assumed proxy for investors' expectations, were
revised up significantly over the second half of the 1990s and into 2000.' Over that same period,
risk spreads on corporate bonds rose markedly on net, implying a rising probability of default.
Default, of course, is generally associated with negative earnings. Hence, higher average
expected earnings growth coupled with a rising probability of default implies a greater variance
of earnings expectations, a consequence of a lengthened negative tail. Consistent with a greater
variability of earnings expectations, volatility of stock prices has been elevated in recent years.
The increased volatility of stock prices and the associated quickening of the adjustment
process would also have been expected to be accompanied by less volatility in real economic
variables. And that does appear to have been the case. That is, after all, the purpose of a
prompter response by businesses: to prevent severe imbalances from developing at their firms,
which in the aggregate can turn into deep contractions if unchecked.
As might be expected, accumulating signs of greater economic stability over the decade
of the 1990s fostered an increased willingness on the part of business managers and investors to
take risks with both positive and negative consequences. Stock prices rose in response to the
greater propensity for risk-taking and to improved prospects for earnings growth that reflected
emerging evidence of an increased pace of innovation. The associated decline in the cost of
equity capital spurred a pronounced rise in capital investment and productivity growth that

are earnings-weighted projections for S&P 500 corporations as reported by
securities analysts to I/B/E/S, a financial research firm. The roughly twenty-year history of this
series confirms a pronounced upward bias in these long-term projections of analysts of
approximately 4 to 5 percentage points in annual expected growth. There is little evidence,
however, one way or the other, of bias to changes in the rate of growth.

-3broadened impressively in the latter years of the 1990s. Stock prices rose further, responding to
the growing optimism about greater stability, strengthening investment, and faster productivity
growth.
But, as we indicated in congressional testimony in July 1999,2 "... 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."
Looking back on those years, it is evident that increased productivity growth imparted
significant upward momentum to expectations of earnings growth and, accordingly, to
price-earnings ratios. Between 1995 and 2000, the price-earnings ratio of the S&P 500 rose from
15 to nearly 30. However, to attribute that increase entirely to revised earnings expectations
would require an upward revision to the growth of real earnings of 2 full percentage points in
perpetuity.3
2

Committee on Banking and Financial Services, U.S. House of Representatives,
July 22, 1999.
3

For continuous discounting over an infinite horizon, k (E/P) = r + b - g, where k equals
the current, and assumed future, dividend payout ratio, E current earnings, P the current stock
price, r the riskless interest rate, b the equity premium, and g the growth rate of earnings. The
relationship holds for both real and nominal variables. If k is assumed to be 0.6, the average over
the second half of the 1990s (taking account of payouts made through share repurchases), a rise
in the P/E of the S&P 500 from 15 to 30, with r and b unchanged in real terms, implies an

-4Because the real riskless rate of return apparently did not change much during that
five-year period, anything short of such an extraordinary permanent increase in the growth of
structural productivity, and thus earnings,4 implies a significant fall in real equity premiums in
those years.
If all of the drop in equity premiums had resulted from a permanent reduction in cyclical
volatility, stock prices arguably could have stabilized at their levels in the summer of 2000. That
clearly did not happen, indicating that stock prices, in fact, had risen to levels in excess of any
economically supportable base. Toward the end of that year, expectations for long-term earnings
growth began to turn down. At about the same time, equity premiums apparently began to rise.
The consequent reversal in stock prices that has occurred over the past couple of years
has been particularly pronounced in the high-tech sectors of the economy. The investment boom
in the late 1990s, initially spurred by significant advances in information technology, ultimately
produced an overhang of installed capacity. Even though demand for a number of high-tech
products was doubling or tripling annually, in many cases new supply was coming on even faster.
Overall, capacity in high-tech manufacturing industries rose more than 40 percent in 2000, well
in excess of its rapid rate of increase over the previous two years. In light of the burgeoning
supply, the pace of increased demand for the newer technologies, though rapid, fell short of that
needed to sustain the elevated real rate of return for the whole of the high-tech capital stock.

increase in g of 0.02 in real terms.
4

If earnings are a constant share of output in the long run, then real long-term earnings
growth is the product of productivity growth and growth in labor force hours. In this exercise,
the growth rate of hours, driven by demographics, is assumed not to change; hence, the growth
rates of earnings and productivity are the same.

-5Returns on the securities of high-tech firms ultimately collapsed, as did capital investment.
Similar, though less severe, adjustments were occurring in many industries across our economy.
Some decline in equity premiums in the latter part of the 1990s almost surely would have
been anticipated as the continuing absence of any business correction reinforced notions of
increased secular stability. In such an environment, the relatively mild recession that we
experienced in 2001 might still have been expected to leave equity premiums below their
long-term averages. That apparently has not been the case, as the tendency toward lower equity
premiums created by a more stable economy may have been offset to some extent recently by
concerns about the quality of corporate governance.
***
The struggle to understand developments in the economy and financial markets since the
mid-1990s has been particularly challenging for monetary policymakers. We were confronted
with forces that none of us had personally experienced. Aside from the then recent experience of
Japan, only history books and musty archives gave us clues to the appropriate stance for policy.
We at the Federal Reserve considered a number of issues related to asset bubbles—that is, surges
in prices of assets to unsustainable levels. As events evolved, we recognized that, despite our
suspicions, it was very difficult to definitively identify a bubble until after the fact~that is, when
its bursting confirmed its existence.
Moreover, it was far from obvious that bubbles, even if identified early, could be
preempted short of the central bank inducing a substantial contraction in economic activity—the
very outcome we would be seeking to avoid.

-6Prolonged periods of expansion promote a greater rational willingness to take risks, a
pattern very difficult to avert by a modest tightening of monetary policy. In fact, our experience
over the past fifteen years suggests that monetary tightening that deflates stock prices without
depressing economic activity has often been associated with subsequent increases in the level of
stock prices.
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, the Federal Reserve raised the federal funds target 300 basis points.
Stock prices initially flattened, but as soon as that round of tightening was completed, they
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.5
Such data suggest that nothing short of a sharp increase in short-term rates that engenders
a significant economic retrenchment is sufficient to check a nascent bubble. The notion that a
well-timed incremental tightening could have been calibrated to prevent the late 1990s bubble is
almost surely an illusion.
Instead, we noted in the previously cited mid-1999 congressional testimony the need to
focus on policies "to mitigate the fallout when it occurs and, hopefully, ease the transition to the
next expansion."
* **

5

Stock prices peaked in March 2000, but the market basically moved sideways until
September of that year.

-7It seems reasonable to generalize from our recent experience that no low-risk, low-cost,
incremental monetary tightening exists that can reliably deflate a bubble. But is there some
policy that can at least limit the size of a bubble and, hence, its destructive fallout? From the
evidence to date, the answer appears to be no.6 But we do need to know more about the behavior
of equity premiums and bubbles and their impact on economic activity.7
The equity premium, computed as the total expected return on common stocks less that
on riskless debt, prices the risk taken by investors in purchasing equities rather than risk-free
debt. It is a measure largely of the risk aversion of investors, not that of corporate managers. An

6

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 equity; 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 raised margin requirements is to price out 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.
7

The sharp stock market contraction on October 19,1987 of more than one-fifth requires
especial further study. Equity prices rose sharply during the spring and summer, again despite
the rise in short-term rates through late summer of that year. The price collapse clearly had some
of the characteristics of prolonged and far larger bubbles, but stock prices quickly stabilized
without significant effect on economic activity. And, in line with later episodes, the failure of the
collapse to have an economic impact seems to have contributed to subsequent higher stock
prices.

-8increased appetite for risk by investors, for example, is manifested by a shift in their willingness
to hold equity in place of psychologically less-stressful, but lower-yielding, debt.
In this case, the cost of equity confronting corporate managers falls relative to the cost of
debt. With greater access to lower-cost equity, managers are able to finance a higher proportion
of riskier real assets with a lessened call on cash flow and fear of default.
Thus, it is generally the changing risk preferences of investors, not of corporate managers,
that govern the mix of risk investment in an economy. Managers presumably employ market
prices of debt and equity coupled with the calculated rate of return on particular real investment
projects to determine the level of corporate investment. To be sure, managers' personal sense of
risk aversion can sometimes influence the capital investment process, but it is probably a
secondary effect relative to the vagaries of investor psychology.
Bubbles thus appear to primarily reflect exuberance on the part of investors in pricing
financial assets. If managers and investors perceived the same degree of risk, and both correctly
judged a sustainable rise in profits stemming from new technology, for example, none of a rise in
stock prices would reflect a bubble. Bubbles appear to emerge when investors either
overestimate the sustainable rise in profits or unrealistically lower the rate of discount they apply
to expected profits and dividends. The distinction cannot readily be ascertained from market
prices. But the equity premium less the expected growth of dividends, and presumed earnings,
can be estimated as the dividend yield less the real long-term interest rate on U.S. Treasuries.8

8

From footnote 3, k (E/P) = D/P = r + b - g, where D is current dividends. Hence,
D/P - r = b - g

-9If equity premiums were redefined to include both the unrealistic part of profit projections
and the unsustainably low segment of discount factors, and if we had associated measures of
these concepts, we could employ this measure to infer emerging bubbles. That is, if we could
substitute realistic projections of earnings and dividend growth, perhaps based on structural
productivity growth and the behavior of the payout ratio, the residual equity premium might
afford some evidence of a developing bubble. Of course, if the central bank had access to this
information, so would private agents, rendering the development of bubbles highly unlikely.
Bubbles are often precipitated by perceptions of real improvements in the productivity
and underlying profitability of the corporate economy. But as history attests, investors then too
often exaggerate the extent of the improvement in economic fundamentals. Human psychology
being what it is, bubbles tend to feed on themselves, and booms in their later stages are often
supported by implausible projections of potential demand. Stock prices and equity premiums are
then driven to unsustainable levels.
Certainly, a bubble cannot persist indefinitely. Eventually, unrealistic expectations of
future earnings will be proven wrong. As this happens, asset prices will gravitate back to levels
that are in line with a sustainable path for earnings. The continual pressing of reality on
perception inevitably disciplines the views of both investors and managers.
As I noted earlier, the key policy question is: If low-cost, incremental policy tightening
appears incapable of deflating bubbles, do other options exist that can at least effectively limit
the size of bubbles without doing substantial damage in the process? To date, we have not been
able to identify such policies, though perhaps we or others may do so in the future.

-10It is by no means evident to us that we currentlyhave— or will be able tofind—

a

measure

of equity premiums or related indicators that convincingly presage an emerging bubble. Short of
such a measure, I find it difficult to conceive of an adequate degree of central bank certainty to
justify the scale of preemptive tightening that would likely be necessary to neutralize a bubble.
As we delve deeper into the questions raised by the developments of recent years, the
interplay between structural productivity growth and equity premiums, so evident during the past
business cycle, is bound to play a prominent role. We need particularly to determine whether the
periodic emergence of market bubbles, which have occurred so often in the past, is inevitable
going forward. As financial wealth becomes an ever-more-important determinant of activity, we
need also to understand far better how changing equity premiums affect and reflect real and
financial investment decisions. If the equity premium has so demonstrable an influence on our
economies as it appears to have, the value of further investigation of this topic is evident.
***
In conclusion, the endeavors of policymakers to stabilize our economies require a
functioning model of the way our economies work. Increasingly, it appears that this model needs
to embody movements in equity premiums and the development of bubbles if it is to explain
history.
Any useful model needs to credibly simulate counterfactual alternatives. We must
remember that structural models that do a poor job of explaining history presumably also will
provide an incomplete basis for policymaking. Often the internal structure of such models has
been employed to evaluate the effect of various stabilization policies. But the results from
models whose internal structure cannot successfully replicate key features of cyclical behavior

-11must be interpreted carefully. The recent importance of movements in equity premiums and
asset bubbles suggests the need to better understand and integrate these concepts into the models
used for policy analysis.
I anticipate productive discussion of these and other issues related to stabilization policy
over the next couple of days.