Add to ORKG116 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1997.The third essay presents a continuous time model to describe the optimal investment strategy of money managers. A manager seeks the optimal skill level that has the best trade-off between the portfolio's expected return and its volatility of tracking error. When the time is close to the end of the assessment period, poor performers increase expected returns by raising skill levels but good performers reduce the volatility of returns by decreasing skill levels. In the comparative analyses, a lower skill level is chosen when the contribution to expected return per unit skill level is higher. When group securities is more volatile and thus the tracking error is not easily t...