Meet Danny. (Danny is a teaching example, not a real reader — but his situation is very common.)
Danny worked at the same company for 22 years. When he retired, most of his savings sat in that one company's stock. It had been good to him. The price had climbed for years, and every time he looked at his account, the number made him smile.
Then the company had one bad year. Not a scandal. Not a collapse. Just a bad year, the kind every company has sooner or later. Its stock dropped by about a third.
Danny's account dropped almost as much. Not because he had picked dozens of bad investments. Because he really only had one.
Here is the part that matters: Danny was not careless, and he was not stupid. He had simply never been shown a way to check whether his money was healthy. He only knew how to check whether it was up.
Those are two different questions. This page teaches the second one.
The plain definition
Your portfolio is just a word for everything you own as investments, added together: every stock, every fund, every account.
A healthy portfolio is not one that is going up. Prices go up and down for everybody. A healthy portfolio is one that is built to take a hit: no single company can sink it, you are not accidentally owning the same company several times over without knowing it, and the fees quietly taken out each year are small enough that they do not eat your progress.
Health is about how your money is spread, not about picking winners. Nobody can promise you winners. Anybody can check their spread.
See it in your own numbers
You do not need special software for this. You need your list of what you own and five quiet minutes. Here are the three checks, with one made-up example. (The numbers are invented for teaching; yours will differ.)
Say everything you own adds up to $10,000: $6,000 in one company's stock, $3,000 in a broad basket fund (a fund holding many companies at once), and $1,000 spread over a couple of smaller things.
Check 1 — the top-heavy check. How much of everything rides on your single biggest holding? Here, $6,000 of $10,000 — that is 60% on one company. A common classroom rule of thumb: once one stock passes about a quarter of everything you own, that company's news starts deciding your whole account's mood. Watch: if that stock drops by a third, you lose about $2,000 — a fifth of everything — from one company's bad year. That is what happened to Danny.
Check 2 — the overlap check. Funds own stocks too. If your basket fund's biggest holding happens to be the same company as your big stock — and for the most popular funds, the biggest holdings are the most popular companies — then you own that company twice: once directly, once inside the fund. Your list looks more spread out than your money actually is.
Check 3 — the fee check. Every fund charges an expense ratio: a yearly fee, written as a small percent, taken quietly out of the fund. On $3,000, a 0.50% fee is $15 a year. A 0.05% fee is $1.50. Neither ruins you alone. But fees are charged every year, in good markets and bad, so small differences grow teeth over a decade.
Notice what none of these checks did: none of them told you to buy anything, sell anything, or predict anything. They told you where you stand. Knowing where you stand is the whole game.
Questions beginners ask
Does a healthy portfolio mean it never goes down?
No. In a bad market, almost everything goes down together, healthy portfolios included. Health is not about avoiding drops. It is about making sure no single company's bad week can knock you out.
My account is up a lot this year. Isn't that the same as healthy?
It is not. “Up” describes price. “Healthy” describes spread. A single stock that doubled made its owner happy and left them one bad year away from Danny's story. The three checks work the same whether your account is up or down.
How often should I run this check?
Once a week is plenty for most people. Checking daily mostly checks your mood. We built our Sunday email around a calm weekly rhythm for exactly this reason.
Do I have to upload my accounts or sign up anywhere to do this?
No. A pencil, your list, and this page will do it. Our free checker (below) just does the arithmetic for you — and it runs in your own browser, because your list is nobody else's business.
Keep learning
Diversification, Explained Simply — the spread idea behind Check 1, taught with one street of shops.
What Is a Dividend? — the paycheck some stocks send you, and the two dates that matter.
Run the check on your own list — free. Our Health Score runs these same three checks on what you own and gives you the verdict in plain English: Run the free Health Score →. It works entirely inside your browser. Your list is never uploaded, we never see it, and there is no account to create — because checking your money's health should never require handing your money's details to strangers.
Education only: this page teaches a way of looking at your investments. It is not financial advice, it is not a recommendation to buy or sell anything, and the Health Score is a teaching tool, not a professional assessment. Only you know your full situation.