Cable is a foreign exchange term used for the GBP/USD currency pair rate (British pound vs the US dollar). It derives its name from the Transatlantic Cable, a steel cable laid under the Atlantic Ocean in 1858, telegraphically linking the UK with the USA, enabling messages with currency prices to be transmitted between the London and New York Exchanges. The first such exchange rate to be published in The Times appeared in their issue of 10 August 1866.
Optical fibres and satellites have now taken over for both local and international communications, but the nickname has remained in the foreign exchange sector.