Once the event that the ex ante analysis tried to predict is successful, it is possible to compare the expectations with the real ones, which is called ex post. Retrospective ex post predictions helps refine them in the future and sometimes provides additional knowledge. While all forecasts are ex ante, an analysis always includes an analysis immediately after an event. For example, there are often considerable uncertainties about the fundamental performance of the company after a merger. The merger itself is the first event, but the ex ante analysis in this case makes predictions for the next big event to come, such as the first time the combined company announces profits. If a fund manager manages to significantly outperform the market, they have made the right ex post decisions. However, you could have used a monkey throwing darts to choose their actions, so they were ex ante limit-neglect, and you probably shouldn`t trust them with your money. Was it right to buy this lottery ticket? It depends on whether you are speaking ex ante or ex post. The term ex-ante (sometimes ex ante or exante written) is an expression that means “before the event”.  Ex ante or fictitious demand refers to the desire for goods and services that is not supported by the ability to pay for those goods and services. This is also called “people`s desires.” Ex-ante is most often used in the commercial world, where the results of an action or a number of actions are predicted (or intentioned).
The opposite of ex-ante is ex-post. .