Black Wednesday
/ˌblak ˈwɛnzdeɪ/ /ˌblak ˈwɛnzdi/British Finance
noun
(A name given to) Wednesday 16 September, 1992, when a massive surge in sales of the pound, perceived to be weak and overvalued, forced its official devaluation and the exit of the United Kingdom from the European Exchange Rate Mechanism.
Origin
1990s; earliest use found in The Evening Standard. From black + Wednesday.