Many investors, including Paul Tudor Jones or Stan Druckenmiller, have been saying before the Q4 market crash that the stock market is overvalued due to a low interest rate environment that leads to companies swapping their equity for debt and focusing mostly on short-term performance such as beating the quarterly earnings estimates. In the fourth quarter, many investors lost money due to unpredictable events such as the sudden increase in long-term interest rates and unintended consequences of the trade war with China.