The effect of credit ratings of companies operating in the chemical sector, trading in "Borsa İstanbul" on the stock market's prices

The developments that emerged with the globalization movement in the world that started in the 1980s also affected the financial markets. One of these developments has been the elimination of borders between countries in financial markets, the disappearance of physical and legal borders on trade and capital flow between countries and the increase in capital mobility. With the weakening of national borders, investors have also found the opportunity to invest in non-local markets. As a result of this development, international trade and financial transactions increased and new markets that required secured relations over long distances were needed. Because the volatility in financial markets has increased the risk perception of investors. Today, investors can easily and quickly obtain the objective and asymmetric information needed to invest in international areas through credit rating agencies. Although credit rating agencies state that the ratings they publish are only opinions, the ratings published for investors cause significant changes in investment decisions. In this study, using the event study method, the ratings published by credit rating agencies are compared to Borsa İstanbul A.Ş. An attempt was made to measure the impact on the stock markets of companies listed in the (BIST) chemical sector. Within the scope of the analysis, the rating and outlook statements made by different credit rating agencies for BIST Chemical sector companies between 2004 and 2022 were analyzed using the event study method. As a result of the analysis, no meaningful and generalizable returns were found for the BIST chemical sector, and it was concluded that there was no information leakage that could be generalized for the entire market, especially before the rating and outlook announcements, and that the market was observed to be in an efficient structure.