In the financial sector, the term "Black Swan" refers to events that have a low probability of occurring but, if they were to occur, would lead to major changes in the market.
An example of this is the Brexit referendum, which took place in the United Kingdom on June 23, 2016, and which led to an unexpected decision: to leave the European Union. The event caused major disruptions within the market, as its occurrence was highly unlikely.
Every year in early January, a list of possible "black swan" events is drawn up, which, if they occur, could have very significant consequences for the markets.