London's "Big Bang" of 1986
London's "Big Bang" was a revolutionary set of market reforms launched on 27 October, 1986. The reforms transformed the City of London from a rather parochial "gentleman's club" to a global financial powerhouse and center of capital markets. Foreign banks and trading companies moved in and took over smaller banks and brokers. The "Big Bang" introduced a more U.S.-style business culture in which the long (and often liquid) lunch went out the window and a cut-throat competitive atmosphere took its place. 
The Big Bang abolished fixed commissions at the London Stock Exchange, which at the time was an exclusive association of small financial houses that dominated the U.K. trade in stocks and bonds. The move unleashed competition and broke down the barrier separating brokerage firms, which executed customer's trades, from proprietary trading firms. That separation had ensured that brokers didn't bet against their clients. It had also prevented firms from getting big enough to be a threat to the entire system.
Without their fixed commissions, brokers and jobbers had to expand to stay profitable, so they merged with big global banks, such as Citicorp and Barclays Bank, and those banks got into securities dealing, which at the time was banned in the U.S. under the Glass-Steagall Act. They also began experimenting with new financial products including credit derivatives and structured investment vehicles.