Following the stock market crash of 1929, and in light of the ensuing Great Depression, Fisher developed a theory of economic crises called debt-deflation, which attributed the crises to the bursting of a credit bubble. Initially, during the upswing over-confident economic agents are lured by the prospect of high profits to increase their debt in order to leverage their gains. According to Fisher, once the credit bubble bursts, this unleashes a series of effects that have serious negative impact on the real economy: