Philip Ernstberger analyses in his three essays different topics of financial pathologies. Thereby, changes in fundamentals as well as information are considered as the driving force for the behavior of speculators and investors. The first essay deals with currency crises, in which the central bank, through setting the interest rate, steers the economy and defends against speculators. The second essay examines the effects of a rating and possible biases on the coordination of investors and the pricing of debt. In the third essay the author uses forecasts of default probabilities and implied market default probabilities to infer the weighing of information by investors.