How to interpret an investment simulation without promises of gain
A simulation shows scenarios, not guarantees. Here is how to read it carefully.
Short answer: read a simulation as a scenario that depends on assumptions, not as a prediction. Identify what the assumptions are (rate, term, contributions, costs), test worse and better scenarios, deduct fees and inflation and remember that past results and projections do not guarantee future gains. This text is educational and is not investment advice.
What helps before you start
- The simulation, with all the data and the date.
- The list of assumptions used: rate of return, term, initial amount and contributions.
- Information about the product's fees, taxes and risks.
Steps
- Identify the assumptions. Every simulation starts from assumed numbers. What rate of return was used? Is it fixed or estimated?
- See where the rate comes from. Is it a contracted rate, a historical average or a simulator assumption? Historical averages do not guarantee the future.
- Look for what is included and what is not. Were fees, taxes and inflation deducted?
- Test other scenarios. Change the rate to a lower and a higher value. How does the result vary? If a small adjustment changes the result a lot, sensitivity is high.
- Consider risk. Is there a possibility of loss? What swings are possible? A simulation with a single straight line usually hides this.
- Watch the term. Results over long periods depend on many assumptions that may not hold.
- Compare with alternatives. Simulate other options with the same assumptions, to compare fairly.
- Be suspicious of promises. Terms like "guaranteed gain" or "certain return" for risky products are a warning.
- Check who is running the simulation. Whoever sells the product may have an interest in showing the best scenario.
An example
A simulation shows that 500 a month, for 20 years, at 10% a year, would result in a high final amount. On review, Camila noticed the rate did not deduct inflation or taxes and that 10% was an average, not a guarantee. She redid it with 6% and then with 3% and saw the result come out quite different. She started using the simulation to plan the habit of saving, not to predict the final amount. The numbers are illustrative.
Common mistakes
- Treating the simulation as a promise.
- Using optimistic rates: prefer to be conservative.
- Ignoring costs and taxes.
- Relying on past performance.
- Putting all your money on a single assumption.
Next step
Reopen a simulation you have seen and list three assumptions. Ask: what happens if one of them does not hold?
Related tool
The investment return calculator is an educational tool and offers no recommendation.
