Economics at the Swiss Federal Institute of Technology (ETH Zurich), a professor of finance at the Swiss Finance Institute, a professor of Physics and a professor of Geophysics also at ETH Zurich. He is the author 500+ research papers and 7 books. Prof. D. Sornette's research is based on the hypothesis that most extreme risks (and gains) are ``dragon-kings'', that is, they almost always result from maturations and drifts towards a critical instability, with measurable precursors either at the technical and/or socio-economic levels. This leads to a research agenda focusing on the prediction of crises and extreme events in complex systems and in particular of financial bubbles and crashes, and the diagnostic of systemic instabilities. For this, Didier Sornette uses rigorous data-driven mathematical statistical analysis combined with nonlinear multi-variable dynamical models including positive and negative feedbacks. Other applications are earthquake physics and geophysics, financial economics and the theory of complex systems, the dynamics of success on social networks and the complex system approach to medicine (immune system, epilepsy...). In 2008, he launched the Financial Crisis Observatory to test the hypothesis that financial bubbles can be diagnosed in real-time and their termination can be predicted probabilistically.