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La finance comportementale à l'épreuve de la crise

Abstract : The crisis that started in 2007 have challenged the foundations of the financial system and the financial theory. This theory is based on assumptions of conventional finance including the "invisible hand" and the rationality assumption of investors which builds that of market efficiency. This crisis has highlighted the psychology of financial markets, aspects already addressed by J.M Keynes when he developed the concept of "animal spirits" to reflect the uncertainty of the economy. Until the early 1980s, the understanding of psychology has always been the result of an informal approach. Since, the psychology of financial markets has been formalized by behavioral finance. Throughout its development, its theoricians have questioned the rationality assumption of investors on empirical bases. However, no paramount event such this crisis has struck much the postulates of the dominant mainstream. Consequently, the financial theory is at the crossroads. Is the assumption of rationality of investors valid? If so, what are the conditions of its validity? If not, are we departing from the scope of conventional finance and adopt that of behavioral finance? These are all issues that are calling for an overhaul of the financial theory. The Jury of the prize in economics in memory of Alfred Nobel did not err in fact by awarding the 2013 prize to these two schools. However, academics do not seem to decide between them, recognizing their contributions to financial theory and practice. This award suggests the following central question: are the two schools parallel, complementary or contradictory? The first chapter deals with the questioning of the central assumptions of finance, at the base of the most popular business models. The framework of conventional finance has failed to give an explanation to the formation of the housing bubble nor has it helped to provide a unified solution to the crisis. The inadequacy of the assumptions of the classical framework with reality appears especially in a context of high volatility and heightened uncertainty. This challenge opens the way for the introduction of psychological parameters in understanding the phenomena of the market. Behavioral finance develops the psychology of financial markets. The second chapter covers the central concepts of this trend, in order to answer the central question of this thesis. The analysis of this trend and its historical epistemological and paradigmatic development shows it is opposite and sometimes in addition to the classic one. The fact remains that the theoretical framework of this trend is not yet completed nor the formation of a new dominant paradigm achieved. Among the key findings of behavioral finance, psychological tools provide relevant insights to developments in financial markets. The third chapter addresses the biases and heuristics in light of the crisis. The analysis of the crisis shows that heuristics and emotional biases may have led investors to judgment errors. The attention and analysis has focused on beliefs in an abstruse information and environmental context, allowing the development of heuristics. Consequently, the tools of behavioral finance can develop a mental map to this crisis. Behavioral finance seeks to establish a more sophisticated conceptual framework. The theory of "animal spirits" has regained momentum especially among behaviorists of neo-Keynesian orientation. The return to this concept is explained by the growing importance of certain concepts such as confidence, corruption and the role of stories in the context of this crisis. Moreover, collusion and corrupt system operation almost permanently undermine confidence in the financial economy. This fourth chapter shows that trust and corruption stem from human psychology and show the weight of the latter in situations of uncertainty and the relationship between men and earnings.
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Submitted on : Monday, December 14, 2020 - 2:36:39 PM
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  • HAL Id : tel-03064618, version 1




Ali Hajji. La finance comportementale à l'épreuve de la crise. Economies et finances. Université Grenoble Alpes, 2015. Français. ⟨NNT : 2015GREAE011⟩. ⟨tel-03064618⟩



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