Submitted in partial fulfillment of the requirements for the degree of Masters of Management Sciences Business Administration, Durban University of Technology. Durban, South Africa, 2017. / The discipline of corporate finance has undergone numerous transformations over the past two-and-a-half decades. One such change has been in the area of corporate finance. Driven by certain behavioral biases, it has been observed that managers sometimes make subjective decisions that do not always follow the norms of traditional corporate finance. One such behavioral influence is overconfidence or optimism. There is a paucity of research on the impact that managerial overconfidence through corporate investments has on the general movement of a company’s share price. This study bridges that gap by investigating the effect of managerial overconfidence on the share price of 10 companies from the JSE/FTSE top 40 index. Its main objective was to inspect the relationship between managerial overconfidence and share price. The results show the presence of managerial overconfidence observed through the investment-cash flow sensitivity of firms. The fixed effects panel regression reveals that Tobin’s Q which is the proxy measure of the investment-cash flow sensitivity of a firm, does affect the share price. Holding every other explanatory variable constant, an increase in Tobin’s Q causes the share price to rise, which leads to the conclusion that managerial overconfidence does have an influences on the stock price. It is further observed that managerial overconfidence tends to increase with firm size. This is shown by the weak positive correlation between the Q ratio and LnTA, and Q ratio and sales. In order to avoid the possible loss in value of a firm caused by an overconfidence manager, it is recommended that shareholders or owners ensure that the manager clearly understands the company’s objectives and vision. Due to the resultant influence of managers’ on the value of a company’s stock, investors should not only look at a company’s past performance, as well as the price earnings ratio (PE ratio), dividend yield, DPS, or any other market value ratios. They should also consider the characteristics of the CEO before making their investment decisions. / M