Research Collection Journal Article Can We Use Volatility to Diagnose Financial Bubbles? Lessons from 40 historical bubbles Author(s): Sornette, Didier; Cauwels, Peter; Smilyanov, Georgy Publication Date: 2018-03-13 Permanent Link: https://doi.org/10.3929/ethz-b-000229885 Originally published in: Quantitative Finance and Economics 2(1), http://doi.org/10.3934/QFE.2018.1.1 Rights / License: Creative Commons Attribution 4.0 International This page was generated automatically upon download from the ETH Zurich Research Collection. For more information please consult the Terms of use. ETH Library QFE, 2(1): 1–105. DOI:10.3934/QFE.2018.1.1 Received: 14 July 2017 Accepted: 5 November 2017 http://www.aimspress.com/journal/QFE Published: 13 March 2018 Research article Can we use volatility to diagnose financial bubbles? lessons from 40 historical bubbles Didier Sornette1;2∗, Peter Cauwels1 and Georgi Smilyanov1 1 ETH Zurich, Department of Management, Technology and Economics, 8092 Zurich, Switzerland 2 also at the Swiss Finance Institute c/o University of Geneva, 40 blvd. Du Pont dArve, CH 1211 Geneva 4, Switzerland * Correspondence: Email:
[email protected]; Tel: +41(0)446328917. Abstract: We inspect the price volatility before, during, and after financial asset bubbles in order to uncover possible commonalities and check empirically whether volatility might be used as an indicator or an early warning signal of an unsustainable price increase and the associated crash. Some researchers and finance practitioners believe that historical and/or implied volatility increase before a crash, but we do not see this as a consistent behavior. We examine forty well-known bubbles and, using creative graphical representations to capture robustly the transient dynamics of the volatility, find that the dynamics of the volatility would not have been a useful predictor of the subsequent crashes.