Backtest a portfolio: free fixed-mix backtest tool
A portfolio backtest shows how a fixed mix of funds would have done on past prices. Enter up to 10 tickers and the share each one gets. Pick how often to rebalance, and you get the results on a page with its own link. It is free, and you do not need an account.
- Use any US-listed stock or ETF, such as SPY, IEF, or GLD.
- Shares are percentages that add up to 100, such as 60 and 40.
- Rebalance every month, every quarter, or every year.
- Prices are daily, with dividends reinvested and a 0.05% cost on every trade.
- A backtest is hypothetical. It shows the past, not what comes next.
How to backtest a portfolio#
- Enter your tickers. Type one ticker per row, such as SPY for US stocks and IEF for Treasury bonds. Or press one of the classic mixes to fill the form.
- Give each one a share. Shares are percentages of the whole portfolio. The total must reach 100%.
- Pick when to rebalance. Rebalancing sells some of what grew and buys more of what shrank, so the mix stays at your split.
- Press “Backtest this portfolio”. The results open on their own page. The page has a link you can copy or post, on Reddit for example. Anyone with the link sees the same chart and numbers.
- Keep building if you like. Press “Save and keep building” to open the mix in the builder with a free account. There you can pick other dates, compare with another benchmark, or add rules.
What the backtest shows#
The results page shows the same numbers the builder shows for every strategy, so you can compare mixes fairly. What a backtest simulates lists every assumption.
| Result | What it tells you |
|---|---|
| Growth of $1 | How your mix grew next to SPY over the same dates |
| CAGR | The average yearly growth, compounded |
| Max drawdown | The biggest drop from a high point to a low point |
| Volatility | How much the value swings in a typical year |
| Sharpe and Calmar | How much growth you got for the swings and the drops |
| Turnover | How much of the portfolio it traded each year |
| Next-day open line | The same trades made at the next morning’s price |
| Reality checks | The same trades at higher costs, and SPY held at your mix’s level of risk |
Reading a backtest explains how to use these numbers together.
How far back the test goes#
A backtest can only start once every fund in it has prices. SPY’s real prices start in 1993. IEF and TLT start in 2002, GLD in 2004, and VXUS in 2011. So a mix that holds VXUS starts in 2011, even if the rest is older.
The Simulated history option in the builder reaches further back for young funds. GLD, for example, goes back to 1968 with modelled values. These are estimates, and the results say which funds used them. Simulated history explains how each fund is extended.
Why rebalancing matters#
A mix drifts as prices move. Say you start with 60% stocks and 40% bonds. After a strong year for stocks, you might hold 68% stocks and 32% bonds. That is more risk than you chose.
Rebalancing puts the split back. Doing it every month keeps the mix closest to your plan. Doing it once a year trades less, so it pays less in costs. The backtest shows both effects, so you can try each and compare.
Classic mixes to start from#
Each button above the form fills in one of these well-known mixes. Each one also has its own article with its full backtest, its history, and its sources.
| Mix | What it holds | Rebalanced |
|---|---|---|
| Classic 60/40 | SPY 60%, IEF 40% | Every month |
| All Weather | VTI 30%, TLT 40%, IEF 15%, GLD 7.5%, DBC 7.5% | Every year |
| Permanent Portfolio | VTI, TLT, GLD, and SHV, 25% each | Every year |
| Golden Butterfly | VTI, VBR, TLT, SHY, and GLD, 20% each | Every year |
| Ivy Portfolio | SPY, EFA, IEF, VNQ, and GSG, 20% each | Every year |
The Permanent Portfolio article checks the mix once a year, but only trades when a fund has drifted 10 points from its 25%. The form rebalances every year instead. You can add the drift rule in the builder.
What this tool does and does not do#
| Does | Does not |
|---|---|
| Tests a fixed mix of up to 10 US-listed stocks and ETFs | Test options, forex, crypto, or funds listed outside the US. Crypto perps need a Hyperliquid strategy in the builder. |
| Rebalances every month, quarter, or year | Add monthly deposits or withdrawals |
| Uses daily prices with dividends reinvested | Model taxes or broker commissions |
| Charges 0.05% on every trade | Borrow money or sell short. Strategies are long only. |
| Shows results with no account, on a page you can share | Promise future returns. A backtest only shows the past. |
| Opens as a strategy you can change, save, and run, with a free account | Keep your mix private once you post its link. Anyone with the link can see it. |
Turn the mix into a strategy#
In the builder, your mix is one Weight block with your split. That block can grow into a rules-based strategy. For example, an If block can move the mix into bonds when stocks fall below their 10-month average, like Faber’s trend model.
Any saved mix can also run on a free paper account with pretend money, or in your own Alpaca account. Backtesting on Tactfolio covers testing rules as well as fixed mixes. Every tool is on the free trading calculators page.
Keep learning#
- Portfolio rebalancing: how often to rebalance, and what it costs.
- Risk parity: a way to split a mix by risk, not by money.
- Fund pages for SPY, IEF, and GLD, and all ETF pages: facts and daily figures for common building blocks.
- AGG vs BND and IEF vs TLT: bond funds compared, with more ETF comparisons.
- Best portfolio backtesting tools and Portfolio Visualizer alternatives: how this tool compares.
Common questions#
Is this portfolio backtest free?#
Yes. Everything on Tactfolio is free while we build it. Pricing will come with live trading.
Do I need an account?#
No. The results page opens without an account, and its link works for anyone. You need a free account only to save the mix and keep building on it.
Can I share my backtest?#
Yes. Every result has its own link, such as tactfolio.com/r/ followed by a short code. Copy it, or post it to Reddit or X from the page. The page shows the mix, its rules, and its results up to the day you made it. It never shows who made it.
Why does my backtest start later than I expected?#
The test starts when the youngest fund in your mix has its first price. Turn on Simulated history in the builder to reach further back with modelled values for young funds.
Can I backtest single stocks, not only ETFs?#
Yes. Any US-listed stock with daily prices works. The ticker list only holds stocks that still trade, though. Companies that failed are missing, which can make a stock mix look better than it would have been.
Can I compare two portfolios?#
Yes. Save one mix, then open the other and pick the first one as its benchmark. Both are measured over exactly the same dates.
How much should I trust the results?#
Use them to learn how a mix behaves in good and bad years. They are not a forecast. A mix that did well in the past can still fall in the future.
Sources
- Investor Bulletin: Performance Claims, U.S. Securities and Exchange Commission, Investor.gov, accessed October 16, 2026