10,000 Monte Carlo simulations. Forward-looking forecasts from BlackRock, JPMorgan, Vanguard, GMO, Schwab, Invesco. No account needed.
Try QuantCalc Free →Between October 2007 and March 2009, the S&P 500 lost 56% of its value. Real estate dropped 33%. International stocks fared even worse. For anyone who retired in 2007, the sequence of returns risk was devastating.
But here is the question most retirement calculators cannot answer: what would happen to YOUR specific portfolio, with YOUR specific withdrawal rate, under those exact conditions?
We built a tool that answers that question directly.
Standard Monte Carlo retirement calculators use historical averages — something like 10% equity returns with 16% volatility. That tells you what "normal" looks like. It does not tell you what happens when everything goes wrong at once.
Our Portfolio Stress Tester runs your portfolio through named crisis scenarios with realistic parameters:
Each scenario uses Cholesky decomposition to generate correlated asset class returns. This means when stocks crash, bonds and real estate react realistically based on historical co-movements — not independently. In a crisis, correlations spike. Assets that normally diversify each other start falling together. The tool models this.
After running 1,000 simulations under a crisis scenario, you get:
Success Rate: What percentage of simulations end with money remaining? A 60/40 portfolio with a 4% withdrawal rate might show 92% success under normal conditions but drop to 67% under a 2008 replay.
Median Final Portfolio: How much money is left at the end of your planning horizon in the typical case?
10th Percentile Outcome: The near-worst case. This is what matters most for retirement planning — the tail risk.
Maximum Drawdown: The largest peak-to-trough decline across all simulations. This is the number that determines whether you panic-sell at the bottom.
Breaking Point Finder (PRO): This is the feature we have not seen anywhere else. It uses binary search to find the exact equity decline percentage where your portfolio crosses from "likely survives" to "likely fails" — your personal breaking point. Knowing this number changes how you think about risk.
A common mistake in retirement planning: assuming asset classes move independently. In a normal market, US stocks and international stocks have about 0.85 correlation. During the 2008 crisis, that spiked above 0.95. The "diversification benefit" of international stocks nearly disappeared exactly when you needed it most.
Our stress tester models this. The correlation matrix changes per scenario:
This is the difference between a stress test that tells you "stocks might drop 38%" and one that tells you "when stocks drop 38%, your bonds also lose 2% and your real estate drops 15%, because that is how markets actually behave."
With PRO access, you can create custom scenarios. Set expected returns, volatility, and correlation presets for each asset class. Model a specific concern — maybe a 20% tech correction with sticky inflation, or a prolonged low-growth environment like Europe experienced from 2010-2015.
Custom scenarios persist in your browser, so you can revisit them without rebuilding.
Stress scenarios do not just affect portfolio values — they affect your tax situation. A large drawdown may force you to withdraw more from tax-deferred accounts (Traditional IRA/401k), pushing your Modified Adjusted Gross Income higher. This can trigger:
The stress tester integrates with our ACA Cliff Calculator and full retirement planner, so you can model these cascading effects.
The Portfolio Stress Tester is free to use with 3 preset scenarios and 1,000 simulations. PRO users ($99 lifetime) unlock all scenarios, the Custom Scenario Builder, Breaking Point Finder, and up to 5,000 simulations.
No signup required. No email capture. Enter your numbers and run the test.
Related reading:
Run 10,000 Monte Carlo simulations using forward-looking return forecasts — not just historical averages. Free. No account required.
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