The most substantial criticism of the EMH relies upon the assumption that all the investors are rational profit maximisers, and therefore, their investment is reasonable as well. Observations have shown that several investors are affected by herd instinct, a tendency to “churn” portfolios, to under-react or over-react to news and asymmetrical judgments about the causes of previous profits and losses. With the concerns described above, a new theory was proposed based on psychology studies. The behavioural finance approach tries to find and explain the reason behind investors’ behaviour, rather than assume their rationality like the EMH. In the behavioural approach, it is suggested that the investors could be prone to commit mistakes and errors originated by emotional and psychological forces and causing market anomalies (inefficiency in stocks markets) – e.g. the dot com bubble or the reactions seen in the recent global financial crisis.