The phrase Big Bang, used in reference to the sudden deregulation of financial markets, was coined to describe measures, including abolition of fixed commission charges and of the distinction between stockjobbers and stockbrokers on the London Stock Exchange and change from open-outcry to electronic, screen-based trading, effected by Margaret Thatcher in 1986. The day the London Stock Exchange's rules changed on 27 October 1986 was dubbed the "Big Bang" because of the increase in market activity expected from an aggregation of measures designed to alter the structure of the financial market.