There is no generally theory to explain the causes of financial crises but one thing is sure they happen again and again. they involve speculation when assets are bought in the hope that the price will rise or sold in the expectation of a fall in the price. If the price rises those who bought in the asset can sell and make a profit.If the pricefalls,sellers can profit by buying the asset back at a lower price. The objectof speculation con be financial assets such as shares,bonds,or currencies,or physical assets such as land,property,or works of art. Crises happen when the speculation destabilizers the market causing prices to rise or fall dramatically