Abstract
Liquidity is a key attribute for efficient functioning of financial markets. Liquidity is important for investors, the regulator, financial intermediaries and listed companies. However, despite its importance as well as its prominence in the microstructure of financial markets literature, it is still an elusive concept as it may refer to the liquidity of a market, an asset, a fund or a portfolio, or even to the liquidity that a central bank provides. The lack of consensus on the definition of liquidity makes it difficult to quantify it. The aim of this thesis is to investigate the liquidity risk on the CAC 40 market index. This thesis is structured around three main lines : first, the microstructure of financial markets is addressed in order to fully understand the sources and the drivers of liquidityrisk. Particular attention is paid to the role of liquidity in systemic crises and to the impact of new changes in market structure (market deregulation, high-frequency trading,dark pools, etc.) on liquidity risk. Second, we focus on the quantitative measurement of liquidity risk on the CAC 40 market. This is achieved by using the GARCH and ARFIMA models, as well as the VAR (Vector autoregression) models. Third, we address the liquidity risk management through the application of the LCAPM model, the liquidity constrained portfolio model and the Liquidity Value-at-Risk model.