A financial crisis is any of a broad variety of situations in which some financial assets suddenly lose a large part of their nominal value. In the 19th and early 20th centuries, many financial crises were associated with banking panics, and many recessions coincided with these panics. Other situations that are often called financial crises include stock market crashes and the bursting of other financial bubbles, currency crises, and sovereign defaults. Financial crises directly result in a loss of paper wealth but do not necessarily result in significant changes in the real economy (e.g. the crisis resulting from the famous tulip mania bubble in the 17th century).
Many economists have offered theories about how financial crises develop and how they could be prevented. There is no consensus, however, and financial crises continue to occur from time to time.