Last month we spent a lot of time looking at how the market actually works — the mechanisms behind pricing, the systems underneath.
This month we are going to look at something more specific. Concentration. The way capital, ownership and risk are pooling into a smaller number of very large places at a pace and scale that has not been seen in a century.
This week we start with what that looks like at the top of the market. In the coming weeks we will look at what it means for interest rates and what happens when familiar faces recommend things they do not understand. All three stories share a common thread that has direct implications for anyone whose retirement is invested in the current economy.
[You can catch up on last week's issue here.]
Dexter Pierce, Founder
In This Issue
The top ten percent of American listed companies now account for more than three-quarters of total market value. The highest concentration in a century.
The five largest hyperscalers are expected to spend $800 billion on capital expenditure this year. They are borrowing to do it. Amazon's debt-to-cashflow ratio has moved from below the S&P 500 average to more than four times it.
Mega-mergers worth over $10 billion represent 48% of total deal value this year. The highest share on record. When one deal fails, the consequences reach further than they used to.
The retirement question this raises. If the diversified fund in your account is dominated by a handful of massive firms, what does the word "diversified" actually mean?
This Week's Numbers
75%+ — The share of total American listed market capitalization now held by the top decile of companies. The highest concentration in a century, according to Deutsche Bank.
$800 billion — Expected 2026 capital expenditure by five hyperscalers — Alphabet, Amazon, Meta, Microsoft and Oracle — as they race to build data centers. Much of it now debt-funded rather than paid from operating cash flow.
48% — Share of total 2026 deal value made up of mega-mergers worth over $10 billion. The highest on record.
$2.2 trillion — Cash and short-term investments held by S&P 500 companies. Record levels of capital available for acquisitions, buybacks and further capital expenditure — concentrating financial power further at the top.
26 vs. 15 — Price-to-earnings ratios for the largest and smallest quintiles of non-financial American firms. In 2019 the same figures were 18 and 14. The market is now valuing large-company profits at a substantially higher premium than small-company profits.
This Week's Story
Your "Diversified" Fund May Be a Bet on Five Companies
There is a phrase in almost every retirement plan brochure: broad diversification.
It is meant to reassure. You are not putting all your eggs in one basket. You own a little bit of everything. If any one company stumbles, hundreds of others will carry you through. That is what an index fund is supposed to do.
That reassurance deserves a closer look in 2026.
The top ten percent of American listed companies now account for more than three-quarters of the entire market's value — the highest concentration in a century, according to Deutsche Bank. The S&P 500, the most widely held index in American retirement accounts, is weighted by market capitalization. That means when a company grows larger, it takes up a larger share of the index. When you buy the fund, you are buying that weighting. And right now the weighting is heavier at the top than it has been in the working lifetime of anyone reading this newsletter.
The numbers are worth sitting with. Five hyperscalers — Alphabet, Amazon, Meta, Microsoft and Oracle — are expected to spend around $800 billion on capital expenditure this year, most of it going toward the buildout of AI data centers. That is roughly the annual GDP of Switzerland, flowing into infrastructure for one technology story, from five companies that already dominate the market indexes.
Until recently, those companies paid for their capital spending out of cash flow. That is changing. Amazon's ratio of debt to annual free cash flow has moved from below the S&P 500 average in 2019 to more than four times that average today. Alphabet issued $80 billion in new stock in June — a "rounding error" for a $4.4 trillion company, in The Economist's phrase, but a real change in behavior. These are not scrappy startups taking on risk. They are the companies whose weight in your index fund is largest.
Meanwhile, mega-mergers over $10 billion are running at 48% of total deal value this year — the highest share on record. The scale of these deals means the acquirer typically takes on substantial debt, and the target often represents more than half the acquirer's market value. Bain calculated that in nearly half of last year's mega-mergers, the target's value was over 50% of the buyer's market cap. Historically about half of large mergers pay off. When they don't, the consequences at this scale can be substantial.
None of this individually is alarming. Large companies can carry more debt. Capital expenditure on AI infrastructure may prove entirely justified. Regulators may correctly identify problems before they compound.
What is worth naming is the cumulative structure. The market's top decile now represents more of the total than at any point in a century. The largest of those firms are taking on debt at a pace they did not use to. The mergers reshaping the top are getting larger and riskier. And when a market index is weighted by size, every one of those developments concentrates further into the fund the average American retirement plan holds.
The word "diversified" was formulated in a market where the top companies held perhaps 40 percent of total value. That market and the one your retirement account holds today are not the same market. The label has not been updated. The exposure has.
For a well-ordered retirement plan, this is not a reason to abandon market participation. It is a reason to look honestly at what the market participation actually is, and to make sure it belongs where it can afford to be — in the Surplus column, where concentration risk can absorb an adjustment without threatening what the plan was built to deliver. When market-based assets carry the weight of retirement income directly, concentration at the top of the market becomes concentration at the base of a retirement plan. Those are not the same thing.
The Cook Pierce Perspective
The word "diversified" was defined in a market where the largest companies held a much smaller share of total value than they do today. The definition has not changed. The math underneath it has.
This week on our website, what the word actually means in 2026 — and what that changes about how a well-ordered retirement plan is built.
[Read the full Cook Pierce Perspective on our website]
The Long View
Concentration is not new to American markets. There have been prior periods when the largest firms dominated total value — the late 1920s, the Nifty Fifty era of the early 1970s, the dot-com peak. Each of those periods ended in a way that reshaped what "diversified" meant for a generation of investors.
The current concentration is greater than any of them. On our website this week we examine what the historical parallels tell us — and where the current situation is genuinely different from what came before.
[Read The Long View on our website]
The Question Worth Asking
If eight companies making similar bets on similar technology represent most of your "diversified" retirement fund, what happens when one of them stumbles?
On our website this week we work through what the honest answer looks like — and what it changes about how a retirement plan should be structured.
[Read this week's answer on our website]
The Closer
The word "diversified" is doing more work than it can currently support. That is not a failure of any individual investor. It is a description of a market that has changed shape faster than the language used to describe it.
A retirement plan built for the current market is not built to avoid concentration. It is built so that when the concentration adjusts — as concentrations historically do — the adjustment happens somewhere other than in the money you were counting on for the next thirty years.
That is not luck. That is order.
