What are sectors — and why do they take turns?
Zoom between "one company" and "the whole market" and you find the middle layer professionals actually think in: sectors. Learn this layer and market commentary suddenly becomes legible.
The eleven neighborhoods
The standard classification (GICS) sorts every listed company into 11 sectors: Energy, Materials, Industrials, Consumer Discretionary, Consumer Staples, Health Care, Financials, Information Technology, Communication Services, Utilities, Real Estate. Each has its own index, its own ETFs, its own personality:
- Defensives (Staples, Utilities, Health Care): people buy food, power and medicine in any economy — steadier demand, calmer stocks, often dividend-friendly.
- Cyclicals (Discretionary, Industrials, Materials, Energy): fortunes swing with the economic cycle — booms amplify them, recessions bite them.
- Rate-sensitives (Financials, Real Estate): interest rates flow almost directly into their business models, for better and worse.
- Growth-tilted (Tech, Communication): priced heavily on future expectations, so they react strongly when the discount on the future — interest rates — moves. (The full macro wiring is Course 4's subject.)
Rotation: the market's weather pattern
On any given day, sectors rarely move together. Money flowing from one neighborhood to another — sector rotation — is how large investors express views: into defensives when bracing, into cyclicals when optimistic. A day when the index is flat but Energy jumps 2% while Tech drops 2% isn't "nothing happened" — it's a loud reallocation that the single index number hides.
This is observation vocabulary, not a trading system — sector patterns describe crowd behavior; they don't schedule it.
Your company in its neighborhood
A stock's move always has two components: its own story and its neighborhood's. A bank rising on a day all banks rise tells you little about THAT bank. Course 1 taught you to compare against the market; now refine it: compare against the sector too.
In the data
A company usually carries two sector labels in market data, side by side. Here are Apple's:
The official GICS sector says Information Technology, one of the eleven names above, with finer layers under it. The data provider's own label says Technology, from a separate and shorter list. Neither is wrong, but they are different vocabularies: a screen or a comparison written in one and searched in the other quietly finds nothing, and "Technology" in one source may not hold the same companies as "Information Technology" in another.
Try it now
- Find your anchor company's sector — the GICS one, the eleven-name vocabulary above — then open that sector's index or ETF. Apple's is in the table above; its sector's fund, XLK, is linked below.
Open XLK.US in the EODHD Terminal
- Put a number on the comparison. Below are Apple and XLK, the fund that holds the S&P 500's Information Technology sector, on the first and last session of August 2026. For each, last close over first close, minus one, as a percentage. Subtract the sector's from the company's.
That difference in percentage points is the only part of the month that was about your company rather than about its neighbourhood, and it is what a professional means by saying a stock outperformed. 3. Now read the whole neighbourhood map for one session: below are the eleven sector funds of the S&P 500 and each one's move on the latest session. Which neighborhoods are green, which red, and how far apart are the best and the worst? One table — and you're reading the rotation professionals discuss at lunch. Unit checkpoint next — then the final unit: the rules that keep this whole machine honest.