Abstract
This chapter examines the relationship between stock market value of domestic firms traded in stock markets in OECD countries and stock index for 1990-2018 period. As a result of Pedroni Panel Cointegration and Dumitrescu-Hurlin Panel Causality Analysis, there is a relationship between the market values of domestic firms traded on the stock exchange and the stock index. In addition, a two-way causality relationship was found. This situation indicates that this relationship is very powerful. It can be understood that adding domestic companies to the stock market has a significant effect on the stock prices and this will attract foreign investors to enter the market.