Asset price bubble: Difference between revisions
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==The causes of bubbles== | ==The causes of bubbles== | ||
===Herding=== | ===Herding=== | ||
Psychological experiments have demonstrated an inherent human tendency to unconscious ''herding'', and there is evidence to suggest that herding is characteristic of the conduct of both institutional and stock market operators on the stock exchange <ref>[http://www.journalofbehavioralfinance.org/research/pdf/unconsious_herding.pdf Robert R. Prechter: ''Unconscious Herding Behavior as the Psychological Basis of Financial Market Trends and Patterns'', The Journal of Psychology and Financial Markets 2001, Vol. 2, No. 3]</ref>. That conduct may be considered irrational but it has been shown that herding can be rational and that rational herding can generate reinforcing ''information cascades'' <ref>[http://www.info-cascades.info/ Sushil Bikhchandani, David Hirshleifer, and Ivo Welch ''Information Cascades and Rational Herding: An Annotated Bibliography and Resource Reference'']</ref>. Information cascades have been observed in other contexts , and the "''herding''" behaviour with which they are associated has characterised the conduct of the subjects of many experimental studies of human behaviour<ref>Solomon Asch: ''Effects of Group Pressure upon the Modification and Distortion of Judgments'' in H Guetzkow (ed) "Groups,Leadership and Men", Carnegie Press, 1951</ref>. One surge in share prices has been termed "irrational exuberance"<ref>[http://www.federalreserve.gov/boardDocs/speeches/1996/19961205.htm Alan Greenspan: ''The Challenge of Central Banking in a Democratic Society'',(Francis Boyer Lecture of The American Enterprise Institute for Public Policy Research, December 5, 1996) Federal Reserve Board 1996]</ref>, and that term has since been applied to other episodes, but whether the word "irrational" is really justified turns on the choice of interpretation. | |||
Herding behaviour has often been attributed to ill-informed ''noise traders'', but [[John Maynard Keynes]], himself a successful investor, has attributed it also to professional investors: | |||
:"professional investment may be likened to those newspaper competitions in which the competitors have to pick out the six prettiest faces from a hundred photographs, the prize being awarded to the competitor whose choice most nearly corresponds to the average preferences of the competitors as a whole; so that each competitor has to pick, not those faces which he himself finds prettiest, but those which he thinks likeliest to catch the fancy of the other competitors, all of whom are looking at the problem from the same point of view." <ref>[http://ebooks.adelaide.edu.au/k/keynes/john_maynard/k44g/chapter12.html John Maynard Keynes: ''The General Theory of Employment, Interest, and Money'', Chapter 12 (IV), Project Gutenberg]</ref> | :"professional investment may be likened to those newspaper competitions in which the competitors have to pick out the six prettiest faces from a hundred photographs, the prize being awarded to the competitor whose choice most nearly corresponds to the average preferences of the competitors as a whole; so that each competitor has to pick, not those faces which he himself finds prettiest, but those which he thinks likeliest to catch the fancy of the other competitors, all of whom are looking at the problem from the same point of view." <ref>[http://ebooks.adelaide.edu.au/k/keynes/john_maynard/k44g/chapter12.html John Maynard Keynes: ''The General Theory of Employment, Interest, and Money'', Chapter 12 (IV), Project Gutenberg]</ref> | ||
Keynes' insight was supported by an NBER paper by David Scharfstein and others, which demonstrates by means of a model that herding can occur even if all the investors act rationally <ref> Kenneth Froot, David Scharfstein and Stein: ''Herd on the Street, Informational Inefficiencies in a Market with Short-term Speculation'', NBER Working Paper No 3250 February 1990</ref>, and by another model created by Andrei Shleifer, showing the effect s of introducing ''noise traders'' <ref> Andrei Shleifer: ''Inefficient Markets, an Introduction to Behavioural Finance'', Oxford University Press, 2000 [http://www.questia.com/read/110162352?title=Inefficient%20Markets%3a%20%20An%20Introduction%20to%20Behavioral%20Finance] (Questia members)</ref>. | Keynes' insight was supported by an NBER paper by David Scharfstein and others, which demonstrates by means of a model that herding can occur even if all the investors act rationally <ref> Kenneth Froot, David Scharfstein and Stein: ''Herd on the Street, Informational Inefficiencies in a Market with Short-term Speculation'', NBER Working Paper No 3250 February 1990</ref>, and by another model created by Andrei Shleifer, showing the effect s of introducing ''noise traders'' <ref> Andrei Shleifer: ''Inefficient Markets, an Introduction to Behavioural Finance'', Oxford University Press, 2000 [http://www.questia.com/read/110162352?title=Inefficient%20Markets%3a%20%20An%20Introduction%20to%20Behavioral%20Finance] (Questia members)</ref>. | ||
The routine use of ''stop-loss'' orders (that probably contributes strongly to the speed of decline when a stock exchange bubble bursts, and is itself a form of herding behaviour), is widely practised by professional investors <ref>[http://cij.inspiriting.com/?tag=cfd ''Crowding at the Exits'', Contrarian Investors' Journal, January 7th, 2007]</ref>. | The routine use of ''stop-loss'' orders (that probably contributes strongly to the speed of decline when a stock exchange bubble bursts, and is itself a form of herding behaviour), is widely practised by professional investors <ref>[http://cij.inspiriting.com/?tag=cfd ''Crowding at the Exits'', Contrarian Investors' Journal, January 7th, 2007]</ref>. | ||
===The Minsky hypothesis=== | ===The Minsky hypothesis=== | ||
Revision as of 07:58, 7 December 2009
An asset price bubble is characterised by a surge in prices that raises expectations of further increases that generate a succession increases until confidence falters, the bubble "bursts", and prices rapidly revert to an objectively-based level. That is the pattern of events which has characterised hundreds of episodes from the "South Sea Bubble" of the 17th century to the housing bubbles of the early 21st century. In many instance their effects have been transitory and localised, but some have caused extensive economic damage.
For definitions of terms shown in italics, see the glossary on the related articles subpage.
The causes of bubbles
Herding
Psychological experiments have demonstrated an inherent human tendency to unconscious herding, and there is evidence to suggest that herding is characteristic of the conduct of both institutional and stock market operators on the stock exchange [1]. That conduct may be considered irrational but it has been shown that herding can be rational and that rational herding can generate reinforcing information cascades [2]. Information cascades have been observed in other contexts , and the "herding" behaviour with which they are associated has characterised the conduct of the subjects of many experimental studies of human behaviour[3]. One surge in share prices has been termed "irrational exuberance"[4], and that term has since been applied to other episodes, but whether the word "irrational" is really justified turns on the choice of interpretation.
Herding behaviour has often been attributed to ill-informed noise traders, but John Maynard Keynes, himself a successful investor, has attributed it also to professional investors:
- "professional investment may be likened to those newspaper competitions in which the competitors have to pick out the six prettiest faces from a hundred photographs, the prize being awarded to the competitor whose choice most nearly corresponds to the average preferences of the competitors as a whole; so that each competitor has to pick, not those faces which he himself finds prettiest, but those which he thinks likeliest to catch the fancy of the other competitors, all of whom are looking at the problem from the same point of view." [5]
Keynes' insight was supported by an NBER paper by David Scharfstein and others, which demonstrates by means of a model that herding can occur even if all the investors act rationally [6], and by another model created by Andrei Shleifer, showing the effect s of introducing noise traders [7]. The routine use of stop-loss orders (that probably contributes strongly to the speed of decline when a stock exchange bubble bursts, and is itself a form of herding behaviour), is widely practised by professional investors [8].
The Minsky hypothesis
The Shin hypothesis
Examples from history
An account of bubbles in the 18th century, including "The Mississippi Scheme", "The South-Sea Bubble", and "Tulipomania" was published in 1852 [10]
Typical consequences
Frederic Mishkin has identified two categories of asset-price bubble[11]:-
- "credit boom bubbles", in which expectations of increases in the price of some assets, lead investors to borrow against the security of those assets, increasing their demand, and enabling them to use the assets to obtain more credit and increase their leverage, in a positive feedback loop which continues until the bubble bursts. The losses then suffered lead to de-leveraging, a credit crunch, reductions in business investment and consumer expenditure, and a fall in economic activity.
- "pure irrational exuberance bubbles", not involving leveraging and de-leveraging, which do not result in a credit crunch or cause any substantial reduction in economic activity.
The house price bubble that led to the crash of 2009 was an example of the former category, and the relatively benign "dot.com" bubble was an example of the second category.
Leading indicators
Asset price bubbles are easy to identify after they have burst, but difficult to distinguish before that happens. In the October 2009 World Economic Outlook, IMF economists warn that "even the best leading indicators of asset price busts are imperfect"[12].
Notes and References
- ↑ Robert R. Prechter: Unconscious Herding Behavior as the Psychological Basis of Financial Market Trends and Patterns, The Journal of Psychology and Financial Markets 2001, Vol. 2, No. 3
- ↑ Sushil Bikhchandani, David Hirshleifer, and Ivo Welch Information Cascades and Rational Herding: An Annotated Bibliography and Resource Reference
- ↑ Solomon Asch: Effects of Group Pressure upon the Modification and Distortion of Judgments in H Guetzkow (ed) "Groups,Leadership and Men", Carnegie Press, 1951
- ↑ Alan Greenspan: The Challenge of Central Banking in a Democratic Society,(Francis Boyer Lecture of The American Enterprise Institute for Public Policy Research, December 5, 1996) Federal Reserve Board 1996
- ↑ John Maynard Keynes: The General Theory of Employment, Interest, and Money, Chapter 12 (IV), Project Gutenberg
- ↑ Kenneth Froot, David Scharfstein and Stein: Herd on the Street, Informational Inefficiencies in a Market with Short-term Speculation, NBER Working Paper No 3250 February 1990
- ↑ Andrei Shleifer: Inefficient Markets, an Introduction to Behavioural Finance, Oxford University Press, 2000 [1] (Questia members)
- ↑ Crowding at the Exits, Contrarian Investors' Journal, January 7th, 2007
- ↑ Hyun Song Shin: Risk and Liquidity, Chapter3, Clarendon Lectures in Finance, 2009, Oxford University Press, forthcoming[2]
- ↑ Charles Mackay: Memoirs of Extraordinary Popular Delusions and the Madness of Crowds, (Project Gutenberg ebook), first published 1852
- ↑ Frederic Mishkin: Not all Bubbles Present a Risk to the Economy, Financial Times, 9th November 2009
- ↑ Lessons for Monetary Problems from Asset Price Fluctuations, (World Economic Outlook October 2009 Chapter 3) International Monetary Fund 2009