This thesis is devoted to the usefulness of intangible assets disclosure by French listed companies around new equity issues and its impact on stock liquidity. The growing importance of intangibles for companies' competitiveness and growth, besides of their non-recognition often raises the question of the need to complete financial statements by intangible assets voluntary disclosure. Accounting and finance literature shows changes in external users' information needs and highlights their attention for information related to intangibles. Insufficient communication on these assets accentuates information asymmetry in financial markets. It provides also a fertile ground for wealth transfer from uninformed investors to informed investors, as by exploiting private information, they can derive higher returns at the expense of other investors. This situation leads to a decrease in stock liquidity, and therefore to an increase of companies' cost of capital, which becomes more important around equity issues. The study conducted on a sample of French listed companies issuing new equity over the period 2000-2009 shows a low level of intangibles voluntary disclosure. Furthermore, our analysis shows that intangibles voluntary disclosure reduces spread, and increases market depth at the announcement of a capital increase.