One of the largest companies in the world once lost more than 40% of its value in less than a year. Would you have held on without selling? If you think one huge company is enough on its own, this example shows you the risk of concentration. In this tutorial I show you how to analyse a single company on CloudPortfolios, what it really means to have everything in one stock, and what changes when you add something else. I designed the site and its tools myself.
Step 1: find it
You don't need any special section. Type the company's name in the search box at the top, the one that says Search assets…, and pick the result. The site takes you to the portfolio builder with the list already filtered. For the example I use Apple, only because almost everyone knows it; you could repeat it with any other company.
Step 2: give it 100%
Add it with the + button and give it 100% of the weight. You now have a "portfolio" of a single company, and the profile on the right shows what that means:
- Volatility of 26.3% a year. That's how much the price moves up and down. A world equity index moved around 14% over the period analysed: almost half as much.
- Beta of 1.11. When the market rises or falls, this stock tends to move a little more.
- Diversification ratio of 1.00. You hold exactly one independent asset. Nothing else cushions the blows.
Step 3: the report and the fall
Click Full report and scroll down to the drawdown chart. Here the worst fall was −49%, between September 2012 and June 2013. One important detail: the site measures falls without reinvestment, as a percentage of the initial capital. Measured the more usual way, against the stock's value at its peak, the fall using monthly closes was a little over 40%. Either way, it's a lot for just nine months. For comparison, using the site's same measure, the world index's worst fall over the whole period analysed was −28.3%.
The report also shows the cumulative return, and in this example it's high. That's the trap: looking only at that number, it's easy to think you would have held on. But the final return only goes to those who didn't sell in the middle of the fall, and many people would struggle to sit through a drop like that with all their money in it. That's why it pays to look at the fall first.
Step 4: add something else and compare
Now try lowering that company from 100% and adding one or two different assets, for example a world index fund or bonds. With the "what if…?" simulator (covered in the previous tutorial) you see, over the same months, how volatility, maximum drawdown and the diversification ratio change. It's the clearest way to understand what diversification is for: not to earn more, but so that a single piece of bad news doesn't decide the future of your money.
Before you draw conclusions
What you see are hypothetical results based on past prices: price only, no dividends, costs or taxes, with monthly closes in US dollars from an external provider (EODHD), from January 2010 to September 2026. Also, the database only includes companies that still trade: the ones that disappeared along the way don't show up, so examples like this one, if anything, understate the risk. The example helps you understand the risk of concentrating on a single stock; it is not an opinion on that company nor a recommendation to buy or sell it.
For now the tool is free and you don't need to sign up. Look up the company you have in mind and check its worst fall. In the next tutorial we go to the other extreme: an engine that runs more than a billion portfolio evaluations in seconds… and why the best portfolios of the past weren't the best afterwards.
Educational and informational content only, published on 7 November 2026. It is not financial, tax or legal advice, nor a personalised investment recommendation, nor an offer or invitation to buy any product. The company in the example is used only to show how the tool works and the risk of concentration; it is not a recommendation on that stock. Results are hypothetical and based on past prices (price only, no dividends, costs or taxes). Past performance does not guarantee future results, and all investing involves risk, including the loss of capital. Figures may have changed since publication. Before making a decision, consult an authorised professional.