Definition of big bang

sudden deregulation of financial markets. The best such example is the London "Big Bang" of 1986, acclaimed as a major step toward a single world financial market. It eliminated fixed-rate brokerage commissions and ownership limits on non-British firms.

deregulation on October 27, 1986, of London-based securities markets, an event comparable to may day in the United States and marking a major step toward a single world financial market.