Answer:
behavioral finance
Step-by-step explanation:
Behavioral finance focuses on how psychological factors influence markets, and how important they are. E.g. expectations can sometimes be more important than actual results. Stock prices are not necessarily determined using scientific methods, that is why each analyst has his/her own expected future price. No one can know for sure which price is correct, since each analyst will factor certain variables depending on his/her expectations about the future of the company, the stock market, the country's economy and even the world's economy.
Most people would agree that Warren Buffet is generally right when pricing stocks or adjusting stock prices, but even he is not 100% right all the time. Even personal issues affect how investors value stocks. E.g. if the market has been rising and the economy is strong, most investors will be confident and might decide to take higher risks. On the other hand, if the market is not doing so well, investors might be afraid, and they will seek risk free investments. That is the reason why US securities sometimes yield negative returns. It is simply illogical to invest money knowing that you will lose, just leave the money in the bank. But sometimes desperation leads to mistakes.