The 1986 London financial deregulation known as the Big Bang removed fixed commissions on stock-market trades. The reforms took effect on 27 October 1986 and transformed the structure of trading in the City of London.
The settlement followed an agreement between the London Stock Exchange and the British government. It ended the traditional distinction between stockjobbers and stockbrokers, allowed outside ownership of member firms, and introduced wider electronic trading and competition.
Big Bang did not refer to a single new bank or a banking law. It was a broad package of changes to financial-market rules. The term is also unrelated to the cosmological Big Bang, although both expressions describe a major transformation.