Ten companies were 40.6% of Vanguard S&P 500 ETF, VOO, on Sept. 30
The weight rose from 37.9% on June 30, 2026, and Vanguard says the fund can follow the index out of diversified status without a shareholder vote.
Key takeaways
VOO had 40.6% of its net assets in ten companies on Sept. 30, 2026, up from 37.9% on June 30. NVIDIA was 8.4%, Apple 7.4%, Microsoft 5.8% and Alphabet 5.5%. Vanguard lists Alphabet as one company.
Each of those four was above 5% of net assets, and together they were 27.1% of the fund. Microsoft was 4.3% on June 30.
Four companies each sat above 5% of the fund
Information technology was 39.7% of the fund, up from 38.0% on June 30. That was also the S&P 500’s information technology weight on Sept. 30.
The 5% line limits a purchase
Vanguard’s April 28, 2026 statement of additional information says that, with respect to 75% of total assets, the fund may not purchase securities of an issuer if, as a result, more than 5% of assets would be invested in that issuer, except as may be necessary to approximate the index. The same limit, and the same exception, apply to buying more than 10% of an issuer’s voting securities.
The limit is on a purchase, not on what a holding may grow to after prices move. Adding the four weights and comparing 27.1% with 25% is not the test that document states.
The prospectus of the same date says tracking the index could still change the fund’s legal status.
“The Fund may become nondiversified, as defined under the Investment Company Act of 1940, solely as a result of tracking an index. This could occur due to events such as an index rebalance or market movement.”
The prospectus does not say the fund is nondiversified. VOO is the exchange-traded shares of Vanguard 500 Index Fund. As of the April 28 statement of additional information, Vanguard classified that fund as diversified. It may become nondiversified solely because a constituent’s relative market capitalization or index weight changes.
The fund keeps the index’s weights
Vanguard’s fact sheet for Sept. 30 says the fund uses a full-replication strategy and remains fully invested. The prospectus says it holds each stock in approximately the same proportion as its weight in the S&P 500. That is why the fund’s information technology weight matched the S&P 500 on Sept. 30.
The prospectus says the fund will not concentrate in one industry except as necessary to approximate the index. If the index becomes concentrated, the fund may have to concentrate with it.
If matching the index takes the fund from diversified to nondiversified, the April 28 statement of additional information says shareholder approval will not be sought.
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Frequently asked questions
How concentrated was Vanguard S&P 500 ETF on Sept. 30, 2026?
Ten companies were 40.6% of its net assets, up from 37.9% on June 30, and four of them were each above 5%.
Does holding four stocks above 5% break the fund's diversification rule?
Not as Vanguard states the rule, because the 5% limit applies to a purchase, with an exception for matching the index, and not to how big a holding gets after prices move.
Is the fund now nondiversified?
No, Vanguard classified it as diversified as of April 28, 2026, though its prospectus says the fund could become nondiversified just by tracking the index.
Would shareholders get a vote if the fund became nondiversified?
No, the statement of additional information says Vanguard will not ask shareholders to approve the change if it happens because the fund is matching the index.
