Two studies were conducted among professional security analysts to explore their patterns of decision making while managing investment portfolios. In study 1, a computer-based simulation, the analysts' styles differed markedly, with most exhibiting either a momentum or contrarian approach, as indicated by responses to portfolio stock price changes. Study 2 used a verbal protocol procedure and semistructured depth interviews to probe the analysts' thought processes. Momentum and contrarian investors were found to differ on a number of dimensions including price expectations, age, experience, raw performance, risk propensity, cognitive style, knowledge calibration, and strategy adaptivity. Implications and limitations are discussed.