When you look at the table below and see the sector exposure percents, what do you observe? Do these allocations make sense?

That is the sector exposure of the S&P 500 stock index: I used the iShares S&P 500 ETF for a real-world proxy. The source of each image is the index website on iShares, which you can see by clicking on the name of the index ETF.

• Asymmetric is an imbalance. That is, more of one thing, less of another.
• A sector is a specific industry, like Energy (Exxon Mobil) or Telecom (Verizon).
• Exposure is the amount of the position size or allocation.

Most of the sector exposure in the S&P 500 large company stock index is Technology, Financials, Healthcare, and Consumer Discretionary. Consumer Staples, Energy, Materials, Utilities, and Telecommunications have less than 10% exposure each. Exposure to Materials, Utilities, and Telecommunications are almost non-existent. Combined, those three sectors are less than 10% of the index. Industrial has 10% exposure by itself.  But this index is 500 large companies, what about mid size and small companies?

Below is the iShares Core S&P Mid-Cap ETF. Most of the sector exposure in the S&P Mid size stock index is Technology, Financials, Industrial. Healthcare, and Consumer Discretionary. Consumer Staples, Energy, Materials, Utilities, and Telecommunications have less than 10% exposure each. Exposure to Materials, Utilities, and Telecommunications are almost non-existent.

We see this same asymmetric sector exposure theme repeat in the iShares S&P Small Cap index. Half of the sectors are make up most of the exposure, the other very little.

This is just another asymmetric observation… the next time you hear someone speak of the return of a stock index, consider they are really speaking about the return profile of certain sectors. And, these sector weightings may change over time.