The Evidence The record on the EMH is extensive,and in large measure it is reassuring to advocates of the efficiency of markets. Studies fall into three broad categories: 1.Are changes in stock prices random?Are there profitable "trading rules"? 2.Event studies:does the market quickly and accurately respond to new information? 3.The record of professionally managed investment firms. 2020 The Evidence The Evidence ƒ The record on the EMH is extensive, and in large measure it is reassuring to advocates of the efficiency of markets. ƒ Studies fall into three broad categories: 1. Are changes in stock prices random? Are there profitable “trading rules”? 2. Event studies: does the market quickly and accurately respond to new information? 3. The record of professionally managed investment firms