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Correlation and concentration: hidden risk in your portfolio

Five positions can be five separate bets or one big bet in disguise. It depends on how much the stocks move together. Understanding that is the difference between real diversification and an illusion of it.

Lesson 71 of 76 · 3 min read

Five chip stocks are one bet

Correlation measures how much two stocks tend to move together. Stocks in the same industry are usually highly correlated: they react to the same news, the same demand cycle and the same big funds buying or selling the theme. If you own five semiconductor stocks, a single report from one major chipmaker or a new export rule can send all five down on the same morning.

That changes your risk math. Five positions risking 1% each look like five independent 1% bets. If they all fall together, it behaves like one 5% bet. Your portfolio heat is the same number, but the chance of hitting all the stops at once is much higher.

Sector and industry group concentration

Stocks are sorted into sectors (broad areas such as technology or energy) and narrower industry groups (such as semiconductors, software or oil drillers). Stocks in the same group are usually more correlated than stocks that merely share a sector. A software stock and a chip stock are both technology, but they don't always move together.

A simple guideline many traders use: hold no more than two or three positions from the same industry group, and keep any one group under a set share of the account, for example 30% to 40%. When a group is leading, it is tempting to own every stock in it. Owning the best one or two usually captures most of the move.

Earnings dates that cluster

Companies in the same group often report within days of each other. A disappointing report from the first one can drag the rest down before they even report. If three of your five stocks report in the same week, that week carries much more risk than it seems. Check the earnings calendar and see how many of your positions report close together. You might trim one or two, or avoid a new buy in the same group right before its reports. The earnings report lesson explains why these events can cause big gaps.

How to check your exposure

Once a week, list your positions next to their industry group. The Groups page shows each group and how it ranks, so you can see at a glance whether you are spread across leaders or piled into one theme. The Heatmap shows the market by sector and industry, and on a red day it makes clear which areas move as a block.

Ask yourself: if this one group had a bad week, how much of my account would be hit? If the answer is most of it, you are concentrated.

When concentration is fine

Concentration is not always wrong. In a strong market the biggest gains often come from a few leading groups, and owning two or three of their best stocks can be the right decision. The key is to do it on purpose: in a confirmed uptrend, with positions that are already working, and with your total heat kept under your limit. Concentration by choice, with a plan, is a strategy. Concentration by accident is a risk you didn't see.

Common mistakes

  • Counting five stocks from the same group as five separate bets.
  • Buying every stock in a hot group instead of the best one or two.
  • Holding several stocks that report earnings in the same week without noticing.
  • Never checking which groups your positions belong to.

Key points

  1. Highly correlated stocks behave like one larger position.
  2. Limit how many positions and how much of the account sit in a single industry group.
  3. Check groups, the heatmap and the earnings calendar to spot hidden concentration.

Check what you learned

Answer at least 2 of 3 correctly to complete the lesson.

1. You own five semiconductor stocks, each risking 1%. How should you think about it?

2. Three of your five stocks report earnings in the same week. Why does that matter?

3. When can concentrating in one group be reasonable?

Check industry groups → Try it on Ticker&Tape

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