The 1985 agreement that preceded a major U.S. dollar decline and the 1987 stock-market crash was the Plaza Accord.
Finance ministers and central-bank governors from France, Japan, the United Kingdom, the United States, and West Germany signed the Plaza Accord at New York’s Plaza Hotel on September 22, 1985. They agreed that the U.S. dollar was excessively strong and supported coordinated action to encourage its decline.
The dollar subsequently weakened substantially against the Japanese yen and German mark. The change affected trade, interest rates, corporate expectations, and international investment. The agreement is often discussed in histories of the 1987 crash because its economic consequences formed part of the international background.
The Plaza Accord did not directly cause Black Monday, and it was not a stock-market crash. A later 1987 agreement, the Louvre Accord, sought to stabilize exchange rates. These two agreements are frequently confused because both involved major industrial economies and exchange-rate coordination.