1,721,519 research outputs found
The US 2000-2002 market descent: clarification
No full textDidier Sornette and Wei-Xing Zhou respond to the issues raised by Anders Johansen in his comment 'An alternative view' published in Quantitative Finance 3 C6.
Follow the money: The monetary roots of bubbles and crashes
No full textA reduced form model for the join dynamics of liquidity and asset prices is proposed. The self-reinforcing feedback between credit creation and the market value of the financial assets employed as collateral in the bank loans (the so called financial accelerator) is modeled by a coupled non-linear stochastic process. We show that such non-linear interaction produces explosive dynamics in the financial variables announcing a regime change in finite time in the form of a market crash which can also be modeled by the same coupled non-linear stochastic process with inverted signs. Casting the financial accelerator dynamics into a highly stylized macroeconomic model, we study its macro-dynamics implications for real economy and for monetary policy interventions. Finally, by exploiting the implications of the proposed model on the dynamics of financial asset returns, we introduce an extension of the GARCH process, that can provide an early warning identification of bubbles. © 2014 Elsevier Inc
Super-exponential growth expectations and the global financial crisis
Full text linkWe construct risk-neutral return probability distributions from S&P 500 options data over the decade 2003-2013, separable into pre-crisis, crisis and post-crisis regimes. The pre-crisis period is characterized by increasing realized and, especially, option-implied returns. This translates into transient unsustainable price growth that may be identified as a bubble. Granger tests detect causality running from option-implied returns to Treasury Bill yields in the pre-crisis regime with a lag of a few days, and the other way round during the post-crisis regime with much longer lags (50-200. days). This suggests a transition from an abnormal regime preceding the crisis to a "new normal" post-crisis. The difference between realized and option-implied returns remains roughly constant prior to the crisis but diverges in the post-crisis phase, which may be interpreted as an increase of the representative investor's risk aversion
Financial market crashes: Predicting bubbles using the Johansen-Ledoit-Sornette model
No full textIn this project we looked into financial markets. The goal of this project was to find out if a bubble is forming and when the most probable time of bursting would be. that is what we call the critical time. In order to do this we studied the work of Professor Didier Sornette, who is an expert in this field of mathematics. In this bachelor thesis we use the Johansen-Ledoit-Sornette (JLS) model and the Levenberg-Marquardt algorithm to predict the critical time of bubbles. By critical time we mean the most probable time of a bubble to burst, but not for certain: there is always a probability to attain the end of the bubble without bursting. \\We looked at the results Didier Sornette got in his work on Black Monday and tried to obtain the same results. Besides that we investigated the sensitivity of the JLS model and differences between variants of it, also when simulating our own data. In the end we looked at applying the model at real data. For the data we chose the Amsterdam Exchange Index and Bitcoin.Applied Mathematic
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Minimizing extremes
No full textInternational audiencePortfolio diversification often breaks down in stressed market environments, but the co-movement of asset prices in a tail risk regime may be modelled using a coefficient of tail dependence. Here, Yannick Malevergne and Didier Sornette show how such coefficients can be estimated analytically using the parameters of factor models, while avoiding the problem of under-sampling of extreme values.<br/
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Minimizing extremes
No full textInternational audiencePortfolio diversification often breaks down in stressed market environments, but the co-movement of asset prices in a tail risk regime may be modelled using a coefficient of tail dependence. Here, Yannick Malevergne and Didier Sornette show how such coefficients can be estimated analytically using the parameters of factor models, while avoiding the problem of under-sampling of extreme values.<br/
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