This study examines the impact of trading by individual investors, domestic institutional investors, and foreign investors on the volatility of newly listed stocks using the recent IPOs on the Korean Exchange. It is a common phenomenon for newly listed stocks to be accompanied by a large amount of trading immediately after listing, resulting in large stock price increase and increased volatility. This study aims to investigate which of the three investor groups' trading increases the volatility of the IPO market and which plays a stabilizing role in the market. The results of this study show that trading in IPO stocks is mainly driven by retail investors, with a relatively small share of trading by domestic institutions and foreigners. In addition, although there are some differences across time periods, we find that within the first three months of listing, both retail and foreign investors' buying and selling transactions increase the volatility of IPO stocks, while institutional investors' transactions play a stabilizing role in the market. Although retail investors dominated the trading of publicly traded stocks, the impact of each investor group's trading on volatility per transaction was much greater for foreign and institutional investors than for retail investors.