Expected value: looking beyond a single winning trade

A profitable trade can still come from a poor decision. Expected value offers a way to discuss the decision separately from its outcome.

Expected value depends on the possible outcomes and the probabilities assigned to them. Those assumptions are uncertain in investing; neither a winning trade nor an index-fund label establishes a guaranteed long-term profit.

A price move can make a decision feel urgent without changing its assumptions. Write down the possible outcomes and what would change your view before acting. A simulator can illustrate choices, but cannot establish the expected return of a real investment.

These tools explore random choices and simulated outcomes, rather than provide a real investment signal. Define the rules before comparing choices; one simulated win does not establish a reliable method.