What is a market crash?

by David Le Bris (Toulouse Business School)


Despite the importance of the phenomenon, there is no clear definition of what is a market crash. Arguably, market crashes should be related to important news but it is frequently difficult to effectively match historical events with market reactions. For instance, when WWI started in July 1914, the French stock index decreased by a modest 7.14 %; a monthly drop ranked only the 105th in the French stock market history. But, a given fall in percent has a stronger impact on a stable market than it does upon a highly volatile one. A crash is not solely a given percentage decrease but represents a significant discrepancy compared to what has been previously observed.

Thus, crashes need to be identified after having taken into account the prior financial context. I propose a simple new tool to identify market crashes by measuring price variations in numbers of standard deviations of the preceding period rather than in percent. French stock market was used to a low volatility before 1914, thus the modest decrease of 7.14 % represents a fall of 6.09 standard deviations, which is the second worst case in French history. This ranking is much more consistent with history.

In a paper (forthcoming in Economic History Review), this method is applied to long term series of US and French stock prices and UK state bonds. This new tool offers a renewed story of the financial shocks. A better match between crashes and historical events is achieved than with pure price variations. Events that were financially insignificant when measured in percent become important crashes after adjustment for volatility. This improved matching brings new insights to several historical debates.

Consistent with other historical sources pointing out the severity of the 1847 crisis, this episode appears to be in the top ten crashes of the UK bond market whereas it ranks 102th in pure price variations. The start of the American Civil War caused a significant crash, supporting the cost side in the cost/advantage debate about this conflict. The Berlin conference dividing up Africa caused a considerable fall in UK bonds, as if the market took account of the future cost of African colonization for UK public finances. Pre-1914 wars (Franco-Prussian, Russo-Ottoman, Boxer Rebellion in China, Boer War, etc.) led to many crashes on both the French stock and UK bond markets, supporting the traditional narrative of the importance of these confrontations despite the weak price changes they caused in this era of low volatility.

Turning to the 20th century, the outbreak of WWI caused major crashes in both French stock and UK bond markets, mitigating the view of sleepwalking to disaster. It is not possible to distinguish more crashes before than after the creation of the Fed in 1913, whose role in stabilizing financial markets is still being questioned. Two crashes in France during the 1920s caused by monetary issues support analysis of French monetary policy as an important factor in the interwar troubles. Hot episodes of the cold war caused crashes on the US and French stock markets, which is consistent with narratives of the risk of disasters incurred at this time. There was no crash on the French stock and UK bond markets in 1929, supporting the views of a transmission of the Great Depression to Europe through other channels than financial markets. The 2008 crisis differs on this point because both French and US stock markets fell strongly.

Maybe, our understanding of financial mechanisms could be enriched thanks to this new tool.

Le Bris, David, What Is a Market Crash? (March 1, 2016). Economic History Review, Forthcoming. Available at SSRN: https://ssrn.com/abstract=1328305 or http://dx.doi.org/10.2139/ssrn.1328305

Ottoman stock returns during the Turco-Italian and Balkan Wars of 1910-1914

by Avni önder Hanedar (Dokuz Eylül University and Sakarya University, Turkey) and Elmas Yaldız Hanedar (Yeditepe University, Turkey)


Were the military conflicts of 19101914 related to higher risks for market investors at the İstanbul Stock Exchange? Wars are often perceived as bad news, correlated with increasing risks for investors and fluctuations in volatility: there would be fall in stock prices due to expected macroeconomic costs, such as higher inflation and lower production, as companies’ activities and expected returns decrease. On the other hand, if wars’ outcomes were perceived as unimportant for companies’ activities and expected returns, then there would be no significant changes in stock prices and volatility.

Many researchers on financial economics have created a large literature on the effects of different wars, and addressed mixed findings. A pioneering research for the political crises of 1880–1914 is Ferguson (2006), contributing to answering how did investors at the London Stock Exchange view the conflicts on the eve of the First World War. He showed the absence of higher war risk on bonds of Great Powers[1] traded on the London Stock Exchange. In addition, Hanedar et al. (2015) evince that the outbreak of the Turco-Italian and Balkan wars were correlated with a lower likelihood of Ottoman debt repayments, using data on two Ottoman government bonds traded on the İstanbul bourse. As the literature on the İstanbul bourse is limited, new light on this question required to explore risk perceived by stock investors due to the historical conflicts.

A column of Tanin presenting the value of bonds and stocks on 14 November 1910

We focus on the influence of stock returns at the İstanbul bourse during the Turco-Italian and Balkan wars, using unique data on stock prices of 9 popular domestic joint-stock companies in the Ottoman Empire. All these companies played a crucial role for the Ottoman economy and operated in the most attractive sectors, i.e. banking, mining, agriculture, and transportation. Some of them are the Ottoman General Insurance company (Osmanlı Sigorta Şirket-i Umûmiyesi), the Regie (Tobacco) company (Tütün Rejisi), and the Imperial Ottoman Bank (Bank-ı Osmanî-i Şâhâne). The data are manually collected from Tanin, which was a widely circulated daily Ottoman newspaper. This research is the first to provide a historical narrative explaining the changes of Ottoman stock returns due to the wars that took place on the eve of the First World War. It observes only small reactions to the Turco-Italian war, and only for three stocks out of ten examined (see Table 1). This is interesting, as previously (Hanedar et al., 2015) we observed higher responsiveness of government bond prices during the same period.



It would be possible to argue that investors might have believed that the war would not be that harmful for the non-governmental economic and financial sectors. An important aspect supporting the finding is that the companies were either established or supported by foreign investors. Great Powers protected their home countries’ investments both economically and politically. The companies obtained revenue guarantees and privileges from the Ottoman state, making the investors’ investments secure. Great Powers that invested in the Ottoman Empire were expecting its demise soon. Therefore, investors were likely to invest in the companies just for the sake of having territorial claim without much consideration of risk. During the nineteenth century, wars were important sources of the solvency problem, which could explain the sensitivity of government bond prices to the conflicts studied here.

The working paper can be downloaded here

References to this blog post here

[1] The UK, France, Germany, Italy, and Austria-Hungary.