How to check your stock portfolio risk

Start with where your money is concentrated, then examine the evidence behind the score. This five-step check uses a simple stock portfolio to show what you can calculate—and what those calculations cannot tell you.

Last reviewed: 14 October 2026 · By Jim Stromberg

1. Start with current values, not purchase prices

List each stock’s ticker and the current value of that holding. Use the same currency for every line and for any cash. PORTIQA evaluates the values you provide; entering a dollar value beside an unconverted euro value makes the weights misleading. Share counts and your original purchase costs are different inputs from current market values.

The free portfolio analyzer accepts up to 25 holdings. You can try it without an account or broker connection. For example, the line AAPL 4000 means a position currently worth 4,000 in the currency you are using, not 4,000 shares. A risk setting supplies the evaluator’s comparison targets; it is not a personal risk assessment.

2. Find the largest position in a $10,000 example

This hypothetical stock-only portfolio illustrates the arithmetic. The amounts are invented inputs, not current stock prices or a recommended allocation. Cash is zero in this first calculation.

For each position, divide its value by the total invested value: 4,000 / 10,000 = 0.40 = 40%. The largest position is 40%, and the two largest together are 70%. Counting four stocks alone hides that imbalance.

There is no single percentage that makes a stock position suitable for everyone. The useful next question is whether that weight matches the exposure you intended and the loss you could bear. FINRA explains how large exposures to one investment or market segment can amplify losses in its guide to concentration risk.

3. Check concentration across every position

The Herfindahl-Hirschman Index, or HHI, adds the squared decimal weights. For this example:

Its reciprocal is the effective number of positions:

Four equal positions would have HHI 4 × 0.25² = 0.25 and four effective positions. This example has greater weight concentration. The result 3.33 is a comparison of position sizes, not a claim that the portfolio contains 3.33 independent risks.

HHI does not know whether stocks move together. Companies can share sector, country, currency or economic exposures. Review those separately rather than assuming that equal weights establish diversification. For more formulas, see portfolio concentration risk; for the broader concept, see the SEC’s asset allocation and diversification guide.

4. Ask what one stock’s loss would mean

Suppose the $4,000 position falls 25%, while the other positions stay unchanged. The loss is $4,000 × 25% = $1,000, or 10% of the $10,000 stock portfolio. The remaining portfolio value would be $9,000. Equivalently, 40% starting weight × 25% price loss = 10% portfolio loss.

If you also held $2,000 cash outside those stock positions, the same $1,000 loss would be 1,000 / 12,000 = 8.33% of total starting assets. The denominator matters: the stock-position concentration above uses invested value, while this second loss percentage includes cash.

This is a hand-calculated illustration, not a forecast or a stress-test feature in PORTIQA. Other holdings could also fall, and fees, taxes, dividends, currency moves and leverage are excluded. It helps translate a large position weight into an amount you can understand.

5. Read the evidence behind the portfolio score

After running your holdings, start with the largest position and effective positions. Then read the component scores, available market evidence and data gaps. A risk-balance component based on weighted beta is not the same as a maximum-loss estimate, and a quality component is not a complete assessment of a business. The portfolio score guide explains how to interpret these distinctions.

A high composite score cannot guarantee safety or future performance. Check whether tickers resolved correctly, whether the input values are current and whether important evidence is missing. The methodology and data coverage pages explain what the evaluator uses.

Funds need an extra check. PORTIQA treats a fund as one position. It does not look through to underlying holdings or calculate overlap between funds. A fund-heavy portfolio therefore cannot be assessed as though each ticker were a single company. Consult the fund’s holdings disclosures to investigate that exposure.

Keep the next review comparable

Market movements can change position weights even without a trade. For another check, update the market values and keep the risk setting consistent if you want to compare similar inputs. A free account saves up to 10 portfolios so you can reopen their holdings and run a fresh evaluation. Saving does not update values automatically or create a performance or score history.

You can also explore an equal-weight Magnificent 7 example and a single-stock example to see how different structures appear in the report. These are illustrations, not model portfolios to copy.