This study examines the profile of individual stock traders in Saudi stock market and attempts to determine the behavioral finance factors affecting the speculative behavior of investors as well as to discover the strongest predictors. Using questionnaire survey method, 130 individual traders in Saudi stock market were identified for this study. The survey is carried out in the biggest brokerage firms in Dammam, Riyadh, and Jeddah. It appears that more than 50% of the individual stock traders are in the age group of between 30-39 years and most of them are inexperienced traders. The results from the Partial Least Square method show that anchoring, confirmation, representativeness and overconfidence heuristics have a significant relationship with speculative behavior. Anchoring appears to be the main predictor of speculative behavior, followed by confirmation, representativeness, and overconfidence. In contrast, availability, loss aversion, and regret aversion does not play a significant role in the speculative behavior of individual traders. The behavior factors introduced in this study explain 34% of individuals' speculative behavior. The findings provide important implications to Capital Market Authority in Saudi to develop appropriate programs and strategies to help market participants to make better and wiser buying decisions that can aggregate to increase market efficiency rather than just to speculate on the price movement of the stock market.