Write one clear sentence
A good request answers four questions. What kind of company? Where are they listed? How many? What is the most any single one should take up?
For example: "Companies that make most of their money from cybersecurity software, listed in the US, 15 companies, no single one over 10%." If you leave something out, sensible defaults are used, and you can see them in the result.
Be precise about what counts
"AI companies" could mean almost anything. "Companies that make most of their money from chips used in data centres" is a rule that can be checked.
Phrases like "most of their money from", "at least 10 years of rising dividends" or "excluding tobacco" turn a vague theme into something specific.
Choose how to split it
Equal amounts in each company is the simplest and stops giants dominating. Bigger companies getting a bigger share is how most well-known indices work, and concentrates more in the largest names.
A cap per company works with either. It is the easiest protection against one holding taking over.
Read the reasons
Every company comes with a short explanation of why it is in, and usually a list of the ones that were considered and left out.
The picks are made by AI and it can be wrong. Treat the reasons as claims to check. If a company does not fit what you meant, that is worth knowing before anything else.
Look at the bad periods
The test shows how the mix would have behaved using real past prices. The return is the number everyone looks at first. The biggest fall along the way tells you more about whether you could live with it.
Remember this part is a simulation with the benefit of hindsight. The "since made" view shows only what has happened after the portfolio existed, which is the part that cannot be flattered.
Compare with the simple option
Before acting on a themed portfolio, ask what it gives you that a low-cost global tracker would not, and what it costs you in spread and effort.
Sometimes the honest answer is that the tracker is enough. Finding that out is a good use of the tool.
Decide, and write down why
If you go ahead, you buy through your own broker. Note down why you chose it and what would make you change your mind. It is far easier to stay calm in a bad month with your own reasoning in front of you.
The risks
- A portfolio built around one idea is concentrated, however carefully it is put together.
- AI-selected companies can be wrong or miss the point of your request. Check them.
- Tested results are simulations using past prices. They are not forecasts.
Try it yourself
The quickest way to understand a portfolio is to look at one. Here is how to turn this guide into something you can inspect.
- 1
Start from the idea
The button below opens the builder with this guide's idea already typed in. Change any part of it: the number of companies, the countries, the limit per company.
- 2
Read the reason for every company
You get a list of companies, how much of each, and a plain-English reason for each pick. If one looks wrong to you, you can ask for it to be changed.
- 3
Look at the bad years, not just the good ones
The portfolio is replayed against real past prices. Check the biggest fall along the way, and ask yourself whether you could have sat through it.
- 4
Decide for yourself
If you want to act on it, you buy the shares yourself through your own broker. Arithmos never holds your money or places trades.
“Companies that make most of their money from cybersecurity software, listed in the US, 15 companies, no single one over 10%.”
Browsing portfolios other people have published is free. See pricing for what building your own includes. A tested result is a simulation using past prices. It is not a forecast and not a recommendation.
Common questions
How many companies should I ask for?
Enough that no single one can sink the result, and few enough that you can read the reason for each. Somewhere between 10 and 30 is common for a themed portfolio, but it is your call.
Can I change a portfolio after it is built?
You can ask for changes, and you can build a new version with a different sentence. See pricing for what each plan includes.
Does a good test result mean I should invest?
No. It means that mix would have done well in the past, with the benefit of hindsight. Whether to invest depends on your own situation, which Arithmos does not know.
