Asymmetric information

In forex markets and financial markets, one party often does not know enough about the other party to make accurate decisions. This inequality is called asymmetric information. Lack of information creates problem: adverse selection and moral hazard. Adverse selection is the problem before the transaction occurs. It occurs when the potential borrowers who are the most likely to produce an undesirable outcome- the bad credit risks—are the ones who most actively seek out a loan and are thus most likely to be selected.

http://mylovelyforex.wordpress.com/2012/03/20/what-changes-forex-rates-in-forex-market/