Portfolio Backtester
Backtest any mix of stocks or ETFs against the S&P 500, with dividends, rebalancing and recurring cashflows. Every run adds yearly returns, worst drawdowns and an efficient frontier.
ETF and stock backtests use Yahoo monthly adjusted closes when dividend reinvestment is enabled, otherwise closing prices. Monthly bars and partial current months may differ from weekly research charts. SPY is the actual ETF; SPX simulation data is a distinct series.
About this tool
This free portfolio backtester shows how any mix of stocks and ETFs would have performed next to the S&P 500: annualized return, volatility, Sharpe, Sortino and Calmar ratios, beta, maximum drawdown, a growth curve, calendar-year and rolling 3-year returns, and the highest withdrawal rate the portfolio would have survived over the window. Pick a period from one year to the longest history your holdings share, turn dividend reinvestment on or off, choose a rebalancing schedule and add a recurring contribution or withdrawal.
Every run also looks inside the same portfolio: the true sector exposure across all your funds, the stocks hiding in more than one fund, your blended fee and how closely the holdings move together. The efficient frontier button tests thousands of other weightings of the same assets and offers the max-Sharpe, minimum-volatility, risk parity and equal-weight mixes in one click. No account or sign-up is needed.
A backtest is a map, not a promise. Its best use is understanding risk: how deep the drawdowns went, how long recovery took and how the pieces moved together in a crisis. Chasing whichever mix drew the prettiest line is the classic misuse, because the next 20 years will not replay the last 20.
Is this portfolio backtester really free?
Yes. There is no account, no email and no paywall, and no limit on how many backtests you run. Search a ticker or company name, set the weights and press Run backtest.
How do I backtest a 60/40 portfolio?
Add a broad stock fund at 60% and a bond fund at 40%, for example an S&P 500 or total market ETF and an aggregate bond ETF, then choose a rebalancing schedule. The results sit next to the S&P 500, so you can see what the bonds cost in growth and what they saved in the bad years.
Can I backtest an ETF portfolio with dividends reinvested?
Yes, and it is the default: with dividend reinvestment on, every figure is a total return. Switch it off to see price-only returns, which leave out dividend income and understate what a real holder earned.
How far back can I backtest?
As far as the youngest holding allows, since every asset needs a price history for the months being tested. The page warns you when a holding is too new for the period you picked. The S&P 500 benchmark uses Robert Shiller's long-run monthly total-return series.
How does rebalancing change a backtest?
Rebalancing sells what has grown and buys what has lagged to bring the weights back to target. You can rebalance monthly, quarterly or yearly, only when a holding drifts five percentage points from target, or never. Running the same mix under each schedule shows how much of the result came from resetting the weights.
What is a good Sharpe ratio?
Sharpe measures return per unit of volatility. Below 0.5 is weak, 0.5 to 1 is the realistic long-run zone for equity portfolios, and sustained numbers above 1 are rare enough to deserve suspicion of the measurement window.