Disclaimer
Fortfolio is an educational research tool. The summary disclaimer shown in every page footer is reproduced below; the sections that follow expand on each methodological caveat.
For informational purposes only. Not financial advice. Past performance does not guarantee future results. Historical data sourced from public markets. Always consult a qualified financial advisor before making investment decisions.
Look-ahead bias
Every backtest and scenario on this site is constructed from data that exists today. A tool that examines the 2008 crisis already knows which holdings recovered, which never did, and what the underlying economy looked like in 2009. Real investors in 2008 had none of that information. When you read a historical loss or recovery number, treat it as a description of what happened, not as evidence that the same decision would feel comparable in real time.
Survivorship bias
The tickers in our database are the ones that still trade today. ETFs that closed, companies that delisted, and funds that merged are not represented. A portfolio of currently-traded names looks healthier in historical backtests than the average portfolio an investor in that era could actually have held, because the worst outcomes have been removed from the dataset before you arrive.
Simulation caveats
Monte Carlo simulations, Safe Withdrawal Rate sweeps, and efficient-frontier visualisations are statistical exercises constructed by resampling historical return streams. They report what fraction of synthetic paths met a target under the simulation's assumptions — they do not estimate the probability of any real-world outcome. A "95% success rate" is a property of the model, not a guarantee about the future. Block-bootstrap and other techniques reduce one source of error (serial correlation) but cannot correct for regimes the historical record does not contain.
Data sources and attribution
Historical price and volume data is sourced from Yahoo Finance via the yfinance Python library. Index data uses the standard caret-prefixed symbols (^VIX, ^TNX, ^GSPC). All returns are computed from adjusted close prices so that splits and dividends are reflected. Yahoo Finance may correct historical values retroactively; rerunning the same scenario on a different day can produce slightly different numbers as a result.
Refresh cadence
The pricing database is refreshed on a routine schedule. Numbers on this site can therefore lag the live market by a calendar day or more. Where a chart or table includes a "Computed on" or "As of" timestamp, that timestamp is the authoritative source of when the underlying data was captured.
Snapshot semantics
When you share a stress-test or backtest URL, the result is frozen at the moment it was saved. Opening a shared URL months later will show the same numbers, even if the underlying data has since changed. New runs against the same inputs may produce different results — particularly for simulation endpoints, where the random draws are seeded deterministically across builds but the algorithm or input data may have moved on.
India-portfolio guard
Fortfolio includes an Indian-crisis scenario set and an INR corpus mode for the NRI audience. Indian-specific historical coverage is shallower than US coverage; some Indian tickers were listed too recently to appear in the 1997 Asian Crisis or the 2008 Global Financial Crisis windows. When a holding has no return for a given scenario, the per-portfolio renormalisation banner makes the gap explicit rather than silently substituting a zero.
Your responsibility
Nothing on this site is investment advice or a recommendation to buy, sell, or hold any security. Past performance does not indicate future results. Before making any financial decision, consult a qualified adviser who is licensed in your jurisdiction and who can review the full picture of your circumstances.
Educational content. Last updated 2026-06-02.