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Backtests, not forecasts
Backvest backtests real funds over real history, tells you the odds your plan lasts, and says which portfolio would do better — with the honesty to say when the difference is noise.
Free: two portfolios of your own, two-way comparisons, and the retirement odds on the one you star. Premium is $4.99/mo, cancel anytime.
Thousands of futures resampled from the portfolio's own history, in today's dollars. Here is one worked plan, end to end.
Live numbers, recomputed nightly from each fund's real record. Two are shown; tap any card to add it. Portfolios closer than the noise are ranked equal, not ordered.
$10k invested at the start, rebalanced annually, each fund's own record with any stand-in history disclosed. Tap any card to add or remove it.
Premium runs your plan on every portfolio you save, on the model portfolios, and on whatever the Finder turns up — and tells you which one actually lifts your odds. Private preview — member sign in →
Not the best mix in hindsight. Each year the search re-ran on the history available at the time, on eight index funds fixed in advance, and held its pick for the next twelve months. Two temperaments, both shown, against the index and the three-fund: the track record of the method, not of a portfolio — including the years it trailed.
The original broad, multi-asset Finder test with both growth temperaments. · rules v1 · adopted 2026-09-05
$10k from 2006-05 to 2026-08 (20 years). Every 12 months the search was re-run on the months before that date only, its pick held for the next 12; 21 picks, average turnover 14% a year. Net of fund expenses only — net of fund expense ratios only; no taxes, trading costs or advisory fees. The fund list was fixed by hand before the test, not shortlisted on hindsight; the universe is funds tracked today — funds that closed are not in it.
Premium runs the same test on every Finder search you make, so a pick comes with the record of how picks like it held up out of sample. Private preview — member sign in →
Every strategy has a decade it disappointed in. Pick yours and see it, plus what held up instead — and what that alternative cost when the market turned back.
Every strategy has a stretch where it disappointed. Pick yours and see it — plus what held up instead, and what that alternative cost when the market turned back.
What you likely believe: The index wins over the long run and nothing beats it after costs. Mostly borne out — but not in every decade.
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The catch — This is not the better portfolio — it is the one that happened to work when the S&P didn't. Across every 10-year window since 1998 it beat the S&P less than half the time, and it badly trailed the run since 2010. What it shows is that a decade of going nowhere is a real thing that has already happened once.
The most valuable output of a backtest is knowing how much not to trust it. Five rules, applied on every screen.
The free tier tests your own portfolios and shows your starred portfolio's retirement odds. Premium runs your plan on every portfolio, finds the one that lifts it, and keeps the whole thing honest month after month.
| Feature | Free | Premium |
|---|---|---|
| Your own portfolios, backtested | 2 | Unlimited |
| Compare head-to-head | 2 at a time | All at once |
| Fund leaderboard | 5 core funds | All funds & stocks |
| History on comparisons and the leaderboard | Last 10 years | Full history (1990+) |
| Retirement odds on a portfolio | The one you star | Every portfolio, the model portfolios, and Finder results |
| Which portfolio lifts your retirement odds | ||
| The Plan page — levers, stress tests, safe-spend and earliest-retirement solvers | ||
| Tax & asset location — where to hold each fund across taxable, traditional and Roth | ||
| Finder — goal-based portfolio search, stress-tested | ||
| Scenario Lab, Diversify builder and Advanced grid search | ||
| Own the stocks — a diversified basket of the index's names | ||
| Glidepaths — a portfolio whose mix shifts as you age | ||
| Contribution calendar — IRA, 401(k), HSA, 529 and self-employed deadlines, with reminders | Next deadline | Every account, the checklist, and the emails |
| Plan tracking — your retirement odds week by week | ||
| Portfolio performance — year to date, 12 months, since you added it | 12 months and YTD | Every window, each against the S&P |
| Sleeve isolation — how much each holding really drives the result | ||
| Fund menus — paste your 401(k), 403(b) or HSA lineup and rank what you can actually buy | ||
| Weekly report | Where you placed | Full numbers, gaps to close, drift, plan odds |
| Rebalance watchdog on every card |
Backtests, not forecasts. Nothing here is investment advice.