This document discusses using machine learning clustering algorithms to analyze stock market data. It compares the K-means, COBWEB, DBSCAN, EM and OPTICS clustering algorithms in the WEKA tool on a stock market dataset containing 420 instances and 6 attributes. The K-means algorithm had the best performance with the lowest error and fastest runtime. It clustered the data into 4 groups in 0.16 seconds. The COBWEB algorithm clustered the data into 107 groups in 27.88 seconds. The DBSCAN algorithm found 21 clusters in 3.97 seconds. The paper concludes that K-means is best suited for stock market data mining applications due to its simplicity and speed compared to other algorithms.