The Stock Market explains the instability of stock market prices. It describes and assesses theories of the determination of the level of, and fluctuations in, share prices. The practices of fund managers, who now dominate activity on the stock market, are analysed and related to Keynes’s theories. Keynes’s analysis of the stock market was at the heart of his explanation of economic instability and it is apt to reassess his theory at a time when economic instability is greater than at any time since the 1930s. The book provides a wealth of information about the operations of the stock market and returns on investment.