ELI5: Explain Like I'm 5

Concentrated stock

Imagine you have a big bag of candy, but all the candy is the same type - let's say it's all lollipops. That's what having concentrated stock means - it's like having a lot of one type of thing.

When people talk about concentrated stock, they usually mean that someone has a lot of stock in one company. So if you own a lot of stock in a company, say 90% or more, that's considered concentrated stock.

Now, just like with candy, having a lot of one type of stock can be a good thing or a bad thing. If the company is doing really well and the stock price keeps going up, then you're going to be very happy. But if the company isn't doing well, or if something happens to hurt the stock price - like if the company gets sued for something, or if there's a recession and people stop buying the company's products - then you could lose a lot of money.

That's why people usually advise against having too much concentrated stock - it's like having all your candy in one basket. You might get really lucky and end up with a ton of candy, but there's also a chance that all your candy could get lost or stolen or ruined. So it's usually better to have a little bit of different types of candy, or in the case of stock, to diversify your portfolio and own shares in more than one company.