This paper examines the existence of different price reactions to the Implementation of stock dlvldends and rights offerings as the stock market matures over time and the Investor mix changes. For that purpose market reactions at the Istanbul Stock Exchange (lSE) are Investigated during three sub-periods displaying different developmental phases of the market defined In terms of Institutional framework, transactions volumes and related Investor profiles. Differences In price reactions and the accompanying trading volumes are tested as the Investor mix changes and small Investors enter ISE due to the cultivating of awareness about the stock market. Other possible causes of excess returns such as prior knowledge about the stocks being traded or a preferred trading range are also tested. Considering the characteristics of thinly traded emerging markets, non-parametric tests are employed besides traditional event study methodology and results are Immune to the choice of relevant test statistics. The results Indicate that the changing mix of Investors shift the timing of market reaction from announcement to Implementation of stock diVidends and rights offerings. Since Individual Investors, who are attracted by lower relative prices. are not expected to be prompt In timing. excess returns persist over longer event windows and are accompanied by Increasing trading volumes.