Backtests are history, not promises

A backtest tells you what a rule did on past prices. It cannot tell you what it will do next. The two get confused constantly because both are shown as a percentage, and only one of them is a fact.

What a backtest is

A fixed rule run over real historical prices, reporting what it would have returned. The number is a genuine measurement of the past. Nothing about the prices is simulated: Apple traded where it traded.

What a backtest is not

It is not a forecast of your return. The future does not repeat the past on schedule, and a rule that returned well over the last five years can return badly over the next five. A backtest also cannot include:

• costs and spreads exactly as you will pay them
• market conditions that have not happened yet
• your own timing, which is almost never the backtest’s start date

A high number should raise your suspicion as much as your interest. A rule tested over a narrow, favourable window looks excellent and means nothing. Judge a strategy on whether its rule makes sense, not on how good its history looks.

A good backtest is not a good outcome

Backtested returns and your returns are separate things. A plan built on a strategy with an excellent history can start losing money the day you buy it.

Ask Vera and she says the same

You

How did that strategy do?

Vera

Backtested, not live — history, not a promise. I can show you the rule and the assumptions the number came from.

Check the numbers yourself

The strategy data is public JSON at monvera.best/api/strategies: each strategy’s rule, its assumptions, and its walk-forward backtest, as plain data you can pull apart. You do not have to trust a summary of it, including this one.

Whatever the history shows, you can lose money on the live plan.