This paper is concerned with proposing a new market strategy for the segmented markets of the Internet stock trading. Many companies are providing various services for customers. However, the internet stock trading market is glowing rapidly absorbing a wide variety of customers showing different tastes and demographic information, so that it is necessary for us to investigate specific strategy for the segmented markets. General strategy so far in the Internet stock trading market has been to lower transaction fee according to the market trend. As the advent of rapidly enlarging market, however, more specific strategies need to be suggested for the segmented markets. In this respect, this paper applied a self-organizing map (SOM) to 83 questionnaire data collected from the Internet stock trading market in Korea, and obtained meaningful results.