S&P 500 vs Nasdaq-100: holdings, overlap and risk

The S&P 500 held 503 companies across every sector on October 30, 2026. The Nasdaq-100 held 101 Nasdaq-listed non-financial companies on November 2, 2026, overlaps heavily with it and has far more technology, making it more concentrated.

When people say "the Nasdaq", they can mean three different things. This article compares the S&P 500 with the Nasdaq-100, because that is the comparison most readers have in mind.

Key takeaways

• The S&P 500 held 503 constituents in October 2026, the Nasdaq-100 just 101 components and no banks.
• 87 of the 100 Nasdaq-100 companies were also in the S&P 500 in March 2026, so the two overlap heavily.
• Technology was 68.01% of the Nasdaq-100 in September 2026, which concentrates both the gains and the falls.

The two indexes at a glance

An index is a list of companies with a rule for how much weight each one gets. Neither index is a company, so there is no revenue or share price behind it, only a value in points.

The two sector figures come from different classification systems, so they are not a like-for-like split.

"Nasdaq" means three different things

Nasdaq the exchange is where shares are bought and sold. The Nasdaq Composite is a very broad index of Nasdaq-listed securities, with 3,398 components listed on index data as of November 2, 2026. The Nasdaq-100 is the smaller index of large non-financial companies, and it is the one compared with the S&P 500 here.

What each index owns, and how much they overlap

Entry rules explain most of the difference. An S&P 500 candidate must be based in the US and meet a US$22.7 billion market-cap guideline. Market capitalisation is the total value of a company's shares. It also needs a profit under US accounting rules in the latest quarter and over the latest four quarters. The Index Committee still chooses among eligible companies.

The Nasdaq-100 works differently. It requires a primary listing on a US Nasdaq-affiliated exchange, excludes financial-industry companies, property trusts and blank-cheque companies, and sets no minimum or maximum market-cap threshold. At its December annual review, Nasdaq ranks eligible companies by full market value and selects the top 75. It then uses rules that make it harder to remove existing members.

Both lists change. Nasdaq added Moderna and removed Warner Bros. Discovery before market open on October 9, 2026, after Paramount completed its acquisition of Warner Bros. Discovery on October 6. In the S&P 500, Okta is planned to replace Kenvue before trading opens on November 4, 2026. On July 7, 2026, Reuters reported that SpaceX joined the Nasdaq-100 about 15 trading days after its stock-market debut under the new fast-entry rule.

The overlap is the part most people miss. Nasdaq Global Indexes reported that 87 of the 100 Nasdaq-100 companies were also S&P 500 constituents as of March 31, 2026, and that those shared constituents represented about 51% of S&P 500 market capitalization.

Sector weights and concentration

The S&P 500 spreads across eleven sectors. As of October 30, 2026, its weights were Information Technology 37.4%, Financials 12.2%, Health Care 10.3%, Consumer Discretionary 9.0%, Communication Services 8.4%, Industrials 8.1%, Consumer Staples 5.0%, Energy 3.9%, Utilities 2.1%, Real Estate 1.8% and Materials 1.7%.

The Nasdaq-100 breakdown as of September 30, 2026 was Technology 68.01%, Consumer Discretionary 15.14%, Telecommunications 5.91%, Health Care 3.78%, Industrials 2.82%, Consumer Staples 1.73%, Basic Materials 1.16%, Utilities 1.01%, Energy 0.44%, with Financials and Real Estate at 0.00% each.

More holdings does not mean low concentration, because both indexes weight companies by market value. On September 30, 2026, NVIDIA was 8.35% of State Street's S&P 500 tracking fund and 8.36% of the Nasdaq-100. Apple was 7.34% and 7.38%, Microsoft 5.75% and 5.78%. Micron was the clearest gap: 1.82% in the S&P 500 fund and 5.04% in the Nasdaq-100.

For a reader whose salary, share options or clients already depend on technology, a technology-heavy index adds to exposure they already carry. For more on the companies at the top of both lists, see our piece on Magnificent 7 stocks.

Returns, costs and the fund you actually buy

These returns include dividends and are measured in US dollars. Over five years ending September 30, 2026, the S&P 500 returned 13.79% a year. Over ten years, it returned 15.33% a year. The Nasdaq-100 returned 16.56% over five years and 21.16% over ten years.

You cannot buy an index. You buy a fund that tracks it, and the fee comes out of your result.

All four are domiciled in Ireland. A fund quoted in euros or kronor still holds US companies priced in dollars, so the exchange rate moves your result. For the practical steps, read our guide on how to invest in the S&P 500.

Verdict

There is no single winner: it depends on what you want. The decisive fact is overlap and spread. The S&P 500 already contained 87 of the 100 Nasdaq-100 companies in March 2026, plus the financials and property the Nasdaq-100 leaves out.

• The S&P 500 covers eleven sectors and costs 0.07% a year in the iShares Core UCITS funds in September 2026.
• The Nasdaq-100 had 68.01% in technology in September 2026 and a 0.30% annual fee.
• Holding both mostly doubles up on the largest companies, including NVIDIA at 8.35% in the S&P 500 fund and 8.36% in the Nasdaq-100 in September 2026.

Risks

• Both indexes are weighted by market value, so larger companies have greater influence on moves.
• The Nasdaq-100 had 68.01% in technology in September 2026, so one bad sector year hits the whole index.
• Past returns are one period only. The ten-year figures above end on September 30, 2026.
• Both indexes hold US companies priced in dollars, so currency moves change what you get in euros or kronor.
• Membership changes without warning, as with Okta's planned replacement of Kenvue on November 4, 2026.

This article is for information only and is not investment advice.

Frequently asked questions

Does the S&P 500 always hold exactly 500 companies?

No. The methodology describes a target of 500 companies, but the latest snapshot available by November 3 listed 503 constituents as of October 30, 2026, so the live constituent count can exceed 500.

Can the Nasdaq-100 hold more than 100 companies?

Yes, temporarily. Nasdaq's official overview showed 101 components on November 2, 2026. The methodology allows a quick addition for an eligible company in the top 40, which can take the index above 100 until the next review.

Why does the Nasdaq-100 exclude banks?

It is a rule, not a market judgement. The methodology excludes financial-industry companies, property trusts and blank-cheque companies, and requires a primary listing on a US Nasdaq-affiliated exchange outside the Nasdaq Capital Market.

How often does each index change?

The S&P 500's weights are reset quarterly after the close on the third Friday of March, June, September and December. The committee can add companies as needed. The Nasdaq-100 is reviewed in March, June and September, with a full reconstitution in December.

Sources

• Nasdaq: Nasdaq Composite Index Overview (November 2026)
• Nasdaq, Inc.: Nasdaq-100 Index Changes (October 2026)
• Nasdaq Global Indexes: Nasdaq-100 Outperforms the S&P 500 (March 2026)
• Nasdaq Global Indexes: Nasdaq-100 Index Fact Sheet (September 2026)
• S&P Dow Jones Indices: S&P 500 (October 2026)
• S&P Dow Jones Indices: S&P U.S. Indices Methodology (November 2026)
• Nasdaq Global Indexes: Nasdaq-100 Index Methodology (August 2026)
• Nasdaq Global Indexes: Nasdaq-100 Index Fact Sheet (September 2026)

Cover photo by Hans Eiskonen on Unsplash.