How concentrated is the S&P 500?
Last verified: August 20, 2026 against SEC Form N-PORT filings and official iShares holdings dated August 19, 2026
Reviewed by Josh for financial modeling and data. See more by Josh.
A fund that tracks the S&P 500 can own hundreds of stocks and still lean heavily on a small group. In the official IVV holdings snapshot dated August 19, 2026, the ten largest security lines represented 37.22% of the portfolio. Information technology alone represented 36.87%.
The current concentration snapshot
Fund holdings
504
Official IVV fund count on August 19, 2026.
Top 3 securities
20.34%
Nvidia, Apple and Microsoft in this snapshot.
Top 10 securities
37.22%
About $3,722 of each $10,000.
Largest sector
36.87%
Information technology, under the provider's classification.
Every $100, split by the ten largest security lines
Each segment uses the official portfolio weight as of August 19, 2026.
Scroll horizontally to inspect the chart labels. The full values appear in the table below.
What the top holdings mean for a $10,000 investment
The percentages become easier to feel when translated into dollars. A $10,000 IVV position would have roughly $793 tied to its largest security and $3,722 tied to the top ten, before market movements. This is a look-through allocation, not a separate bill or fee.
| Rank | Security | Sector | Portfolio weight | Per $10,000 |
|---|---|---|---|---|
| 1 | Nvidia NVDA | Information Technology | 7.93% | $793 |
| 2 | Apple AAPL | Information Technology | 7.00% | $700 |
| 3 | Microsoft MSFT | Information Technology | 5.41% | $541 |
| 4 | Amazon AMZN | Consumer Discretionary | 3.92% | $392 |
| 5 | Alphabet Class A GOOGL | Communication Services | 3.04% | $304 |
| 6 | Broadcom AVGO | Information Technology | 2.58% | $258 |
| 7 | Alphabet Class C GOOG | Communication Services | 2.43% | $243 |
| 8 | Meta Platforms META | Communication Services | 1.80% | $180 |
| 9 | Micron Technology MU | Information Technology | 1.59% | $159 |
| 10 | Eli Lilly LLY | Health Care | 1.52% | $152 |
| Top ten security lines | 37.22% | $3,722 | ||
How security concentration changed since 2019
Public SEC filings give us a repeatable quarterly trail. The top ten security lines rose from 21.56% in September 2019 to 36.42% in March 2026, an increase of 14.86 percentage points. The series peaked at 39.16% in December 2025. That drop after the peak is a useful reminder: concentration changes with relative stock prices, index membership and portfolio rebalancing.
Scroll horizontally to inspect the quarterly chart.
A separate 100% view by sector
Stocks sit inside sectors, so adding stock weights and sector weights in one stack would count the same dollars twice. This second view answers a different question: which parts of the economy drive the portfolio? Information technology is the largest block at 36.87%. Communication services and consumer discretionary also contain several of the largest individual names.
Scroll horizontally to inspect the sector labels. The full values appear in the table below.
| Sector | Weight | Per $10,000 |
|---|---|---|
| Information Technology | 36.87% | $3,687 |
| Financials | 12.19% | $1,219 |
| Health Care | 9.52% | $952 |
| Communication Services | 9.45% | $945 |
| Consumer Discretionary | 9.24% | $924 |
| Industrials | 8.79% | $879 |
| Consumer Staples | 4.58% | $458 |
| Energy | 3.45% | $345 |
| Utilities | 2.06% | $206 |
| Real Estate | 1.83% | $183 |
| Materials | 1.80% | $180 |
| Cash and derivatives | 0.21% | $21 |
Does owning 504 holdings mean you are diversified?
It means you own a broad list, but the dollars are not spread evenly. Market-cap weighting gives larger companies more influence. A one percentage point move in a 7.93% holding matters far more than the same move in a company with a 0.02% weight. That is not a flaw hidden in the product. It is the stated result of weighting by market value.
S&P 500 proxy
504 holdings
Top ten security lines: 37.22%.
Total U.S. market proxy
2,445 holdings
Top ten security lines: 33.06%.
The total-market proxy held 2,445 positions on the same date, yet its top ten still represented 33.06%. That was only 4.16 percentage points below IVV. Adding thousands of smaller stocks can broaden coverage without removing the dominance of the same mega-cap companies.
What concentration tells you, and what it does not
It tells you where portfolio outcomes can come from
When a small group occupies a large share of the fund, those companies can explain more of its short-run performance. Strong results from the leaders can lift the index even when the typical member is flat. The reverse is also true. A broad headline index can fall because a few very large constituents fall, even if many smaller constituents hold up better.
It does not tell you that a crash is imminent
A high weight can reflect years of earnings growth, investor expectations, price appreciation, or all three. The concentration figure does not say whether those expectations are reasonable. It is an exposure measure, not a valuation model and not a market-timing signal. Investors can use it to ask better questions, but the percentage alone cannot answer what happens next.
A rising weight is not the same thing as money flowing in
Suppose one holding rises 20% while the rest of the portfolio is unchanged. Its portfolio weight increases even if nobody directs a new dollar specifically toward that company. Market-cap-weighted funds largely let price changes move the weights for them. New share issuance, buybacks, index changes and fund rebalancing can also move the percentages. The chart therefore measures how the portfolio is distributed at each snapshot, not which stocks investors bought during the quarter. A proper flow analysis needs subscriptions, redemptions or transaction data with a different methodology.
Stock concentration and sector concentration can diverge
The top-stock view asks how much depends on a short list of securities. The sector view asks how much depends on groups of businesses with related classifications. Several large technology holdings can make both measures rise together, but they do not have to. A sector can be large because it contains many medium-sized companies, while the ten largest securities can span several sectors. Classification also simplifies companies whose revenue crosses business lines, so sector labels are a useful map, not a complete description of economic exposure.
The leaders are not permanent
The quarterly SEC series shows that leadership can loosen as well as tighten. The top-ten share fell from 39.16% in December 2025 to 36.42% three months later. That does not reveal which company will lead next, but it does show why a current top-ten table should be treated as a dated snapshot. Market-cap weighting changes the portfolio as relative market values change. Today's largest positions are not guaranteed to remain the largest positions.
Questions worth asking about your own portfolio
Do you own the same leaders elsewhere?
A technology fund, employer stock and an S&P 500 fund can create overlapping exposure. Look through the labels to the underlying positions.
Is your risk budget tied to one sector?
Sector weight can matter alongside individual-company weight because businesses in the same sector can respond to similar economic or regulatory forces.
Would a different weighting method help?
Equal-weight, value-tilted and small-cap funds redistribute exposure, but each introduces different costs, turnover and performance behavior.
Can you stay invested through leadership changes?
The best allocation is not just mathematically diverse. It also has to be one you can hold when yesterday's winners stop leading.
This page is descriptive, not personalized investment advice. Concentration is one dimension of risk. Taxes, time horizon, cash needs, fees and the rest of your household balance sheet also matter.
Methods and source controls
Historical security ranks: We identify IVV using SEC CIK 1100663, series S000004310 and class C000012040. For each quarter-end NPORT-P filing, we keep common equity lines, read the reported percent-of-net-assets field, sort descending and sum ranks 1, 1 to 3, 1 to 5 and 1 to 10. The chart uses non-overlapping buckets so every vertical slice totals 100%.
Current security and sector snapshot: We calculate the headline from official iShares holdings dated August 19, 2026. Sector labels and weights are the provider's current classifications. We retain a small cash and derivatives category rather than forcing every dollar into an equity sector.
Timing: SEC filings arrive after the portfolio date, so the final quarterly point is March 31, 2026 even though the filing was submitted on May 28, 2026. The more recent provider snapshot is shown separately. We do not draw a line between the two as if they were produced by the same reporting pipeline.
Reproducibility: The downloadable data includes every quarterly observation, filing date, accession number, direct filing URL and calculated rank bucket shown here. Readers can trace any point back to its SEC filing and repeat the calculation. We also keep the dated provider snapshot separate from the lagged SEC history so the two sources are never blended silently.
Primary sources
- SEC Form N-PORT data sets, the public source for the quarterly holdings history.
- Latest SEC filing used in the chart, accession 0002071691-26-012459.
- Official IVV fund page and official current holdings, used for the dated current snapshot.
- Official ITOT fund page, used for the same-date total-market comparison.
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