Record Highs Are Lying to You: A Handful of Stocks Are Carrying the Index
How many of the 500 companies in the S&P 500 does it take to make up nearly a third of the index? Ten. By the 2024/2025 figures from S&P Dow Jones Indices, the top 10 holdings accounted for over 30% of the index's total value. The other 490 split the rest.
What a record high actually measures
The common belief goes like this: a record high means the market is healthy, and an index fund means you own the whole market, so 500 companies keeps you safe. It's a reasonable belief. It's also built on a quirk of how the index works.
The S&P 500 is weighted by company size. A giant moves the number far more than a mid-sized firm does. So when the "Magnificent Seven" tech names rise, the index climbs even if the typical company is flat or falling. The record tells you the heavy stocks went up. It says nothing about how many others came along, and analysts call that missing piece market breadth. When breadth is thin, the headline number describes a few companies and the average business gets lost behind it.
Where the diversification story breaks
Picture an Edmonton investor with three funds in a TFSA: an S&P 500 ETF, a global equity fund, and a growth fund. That looks like three separate bets. Open the top-ten holdings of each and the same large US tech names often sit at the top of all three. Paying three fees to own one idea is a poor deal, and few people ever check.
The Canadian version of the problem looks different. The S&P/TSX Composite leans heavily on financials and energy, which makes it sensitive to interest rates and to global oil demand. An Albertan who works in the oilpatch, owns a TSX fund, and holds a house whose value rises and falls with the energy cycle has stacked three bets on the same outcome. Their paycheque, portfolio and home equity all move together, in the same direction, on the same news.
The strongest objection
The fair pushback is that narrow leadership doesn't mean a crash is coming. The giants have the most cash and the best ability to ride out a slowdown. Some analysts argue their prices are earned by real profits and by AI dominance. And the Bank of Canada's rate cuts from 2024 to 2026 could help the other 493 S&P names catch up, which would broaden the market on its own.
All true, and I'm not predicting a crash. But concentration works as arithmetic, and the arithmetic cuts both ways. If the top ten, at roughly 30% of the index, fall 10%, that alone pulls the index down about three percentage points, before a single other stock moves. Historically, when leadership narrows a lot, volatility has often risen as the few winners face profit-taking. You don't have to believe in a crash to want to know how much of your money rides on those ten names.
What to do with a record
Records trigger FOMO, especially for first-time investors who've watched years of inflation shrink their savings while high-interest savings rates have drifted down from their 2023 peaks. The urge to put it all in this week is strong.
A steadier answer is dollar cost averaging, which means investing a fixed amount on a fixed schedule so you aren't betting on one entry date. Pair that with an hour spent on overlap. List the top ten holdings across every fund you own, add them up, and see what share of your portfolio sits in the same handful of companies. Then ask whether you chose that on purpose.
Some people will say yes, and that's a legitimate answer. If you believe in those companies, own them knowingly. Just don't confuse a record index with a record economy.
The number on the screen is a fact about ten companies. Your portfolio should be built around a fact about you.
How many of the 500 companies in the S&P 500 does it take to make up nearly a third of the index? Ten. By the 2024/2025 figures from S&P Dow Jones Indices, the top 10 holdings accounted for over 30% of the index's total value. The other 490 split the rest.
What a record high actually measures
The common belief goes like this: a record high means the market is healthy, and an index fund means you own the whole market, so 500 companies keeps you safe. It's a reasonable belief. It's also built on a quirk of how the index works.
The S&P 500 is weighted by company size. A giant moves the number far more than a mid-sized firm does. So when the "Magnificent Seven" tech names rise, the index climbs even if the typical company is flat or falling. The record tells you the heavy stocks went up. It says nothing about how many others came along, and analysts call that missing piece market breadth. When breadth is thin, the headline number describes a few companies and the average business gets lost behind it.
Where the diversification story breaks
Picture an Edmonton investor with three funds in a TFSA: an S&P 500 ETF, a global equity fund, and a growth fund. That looks like three separate bets. Open the top-ten holdings of each and the same large US tech names often sit at the top of all three. Paying three fees to own one idea is a poor deal, and few people ever check.
The Canadian version of the problem looks different. The S&P/TSX Composite leans heavily on financials and energy, which makes it sensitive to interest rates and to global oil demand. An Albertan who works in the oilpatch, owns a TSX fund, and holds a house whose value rises and falls with the energy cycle has stacked three bets on the same outcome. Their paycheque, portfolio and home equity all move together, in the same direction, on the same news.
The strongest objection
The fair pushback is that narrow leadership doesn't mean a crash is coming. The giants have the most cash and the best ability to ride out a slowdown. Some analysts argue their prices are earned by real profits and by AI dominance. And the Bank of Canada's rate cuts from 2024 to 2026 could help the other 493 S&P names catch up, which would broaden the market on its own.
All true, and I'm not predicting a crash. But concentration works as arithmetic, and the arithmetic cuts both ways. If the top ten, at roughly 30% of the index, fall 10%, that alone pulls the index down about three percentage points, before a single other stock moves. Historically, when leadership narrows a lot, volatility has often risen as the few winners face profit-taking. You don't have to believe in a crash to want to know how much of your money rides on those ten names.
What to do with a record
Records trigger FOMO, especially for first-time investors who've watched years of inflation shrink their savings while high-interest savings rates have drifted down from their 2023 peaks. The urge to put it all in this week is strong.
A steadier answer is dollar cost averaging, which means investing a fixed amount on a fixed schedule so you aren't betting on one entry date. Pair that with an hour spent on overlap. List the top ten holdings across every fund you own, add them up, and see what share of your portfolio sits in the same handful of companies. Then ask whether you chose that on purpose.
Some people will say yes, and that's a legitimate answer. If you believe in those companies, own them knowingly. Just don't confuse a record index with a record economy.
The number on the screen is a fact about ten companies. Your portfolio should be built around a fact about you.
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