How to Analyze Your Stock Portfolio: The 6 Checks Professionals Run
Returns tell you what happened. These six checks tell you why, and what could happen next: concentration, overlap, crash exposure, a fair benchmark, efficiency and dead weight.
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Portfolio Stress Test: How Would Your Portfolio Do in a Crash?
Replay your current holdings through 2008, 2020 and 2022 before the next crash does it for you. Here is how a stress test works, how to run one, and what to do with the result.
Key takeaways
- A stress test replays your current holdings, at today’s weights, through real past crashes.
- It does not predict the next crash. It shows which positions would drive your losses and whether anything cushions them.
- Use several different crashes: a credit crisis, a sudden shock and a rate-driven bear market hurt different holdings.
- Judge the result against what you could live through without selling, not against the index alone.
What is a portfolio stress test?
A stress test asks one question: if a past crisis happened again tomorrow, what would it do to the portfolio you own today? You take your current holdings and weights, apply what each of them did during a historical stress period, and add up the result.
Banks are required to run stress tests on their balance sheets for the same reason you should run one on your portfolio: the time to find out how much you could lose is before it happens, while you can still act calmly.
Which crashes to replay
Different crises hit different things. A useful stress test uses at least three very different ones, so a portfolio that looks safe in one scenario cannot hide a weakness in another.
| Scenario | What happened | S&P 500 peak to trough (approx.) | What it tests |
|---|---|---|---|
| Global financial crisis, 2007–09 | Credit and banking collapse, deep recession | −57% | Leverage, banks, cyclicals, small caps |
| COVID crash, Feb–Mar 2020 | Sudden shock, fastest bear market on record | −34% | Travel, energy, crowded momentum names |
| Rate-hike bear market, 2022 | Inflation and fast rate rises | −25% | Long-duration growth stocks, bonds falling with stocks |
2022 deserves special attention: stocks and bonds fell together, so the classic “bonds will cushion it” assumption did not hold that year.
How to run a stress test yourself
- List your holdings and weights as they are today, including cash and every ETF.
- Get each holding’s return during each stress window (from the market peak to the trough of that episode). Use the same dates for every holding.
- Handle holdings that did not exist yet with a close proxy: a sector ETF or a similar company. Note it, because proxies are the weakest part of any stress test.
- Multiply each return by its weight and add them up. That is your portfolio’s scenario loss.
- Rank the holdings by their contribution to the loss (weight × return), not by their own percentage drop. A small position that fell 80% can matter less than a large one that fell 40%.
A worked example
An illustrative four-holding portfolio in a scenario where the market falls 34%:
| Holding (illustrative) | Weight | Return in scenario | Contribution to loss |
|---|---|---|---|
| Growth tech fund | 45% | −40% | −18.0 pts |
| Broad index fund | 30% | −34% | −10.2 pts |
| Dividend stock | 15% | −25% | −3.8 pts |
| Short-term bonds and cash | 10% | +2% | +0.2 pts |
| Portfolio | 100% | −31.8% |
The growth fund is 45% of the money but more than half of the loss. That single line tells you where your risk lives, which is more useful than the headline number.
Illustrative only, not based on any real account or a prediction.
How to read the result
Turn the percentage into money. A −32% scenario on a $300,000 portfolio is a $96,000 paper loss. Then ask the only question that matters: would you hold through that, or sell near the bottom? If the honest answer is “sell”, the portfolio is too risky for you, whatever its long-term return looks like.
Also check the recovery: how long did it take your holdings to get back to their previous peak after each crash? A portfolio that falls less but takes years to recover can be harder to live with than the numbers suggest.
What to do if the loss is bigger than you can live with
- Trim the largest contributor first: the position with the biggest weight × loss, not the one with the worst percentage.
- Look for clusters: several holdings that fell together are one risk and should be sized as one.
- Add something that behaved differently in the scenario you fear most, rather than more of what you own.
- Re-run the test after each change: one fix can shift the risk somewhere else.
What a stress test cannot tell you
The next crisis will not repeat the last one exactly. Companies change, and proxies are guesses. A stress test is a map of your weak points under conditions that really happened, not a forecast. Use it to size positions sensibly, not to time the market.
Frequently asked questions
List your holdings and weights, look up each one’s return over the same past crash windows (for example 2008, 2020 and 2022), multiply by weight and add up. A spreadsheet and free price history are enough; tools just save time.
One you could live through without selling. Compare the loss in dollars with what you could tolerate, and check which holdings drive it.
No. It replays real past events on today’s holdings to show where your risk sits. The next crisis will be different.
After every significant change in holdings and at least once a quarter.
Run the crash test on your own holdings.
Exent replays your portfolio through 2008, COVID, the 2022 rate hikes and more, and shows which positions would hurt most.
Check my portfolioLimited offer$1.95 for unlimited checks· unlimited checks
Educational content, not investment advice. Examples are illustrative; past performance does not guarantee future results.