Nvidia is the largest holding within the Vanguard S&P 500 ETF (VOO), claiming 7.50 percent of the fund's assets as of June 30. This position places it ahead of Apple, which represents 6.58 percent of the fund—a full percentage point spread across the entire index.

Nvidia currently holds a market value of approximately $5.3 trillion, exceeding Apple's $4.5 trillion valuation by about $800 billion. The Vanguard S&P 500 ETF manages $1.05 trillion across its 520 stock positions.

This reordering reflects no active management decision. An S&P 500 index fund weights companies by float-adjusted market value. Nvidia's most recent fiscal quarter saw revenue grow 85 percent year over year, reaching $81.6 billion. The market repriced the company accordingly, expanding its index position as Apple's valuation remained stable.

Concentration at the top of the S&P 500 ETF is pronounced. After Nvidia and Apple, Microsoft holds 4.29 percent, Amazon accounts for 3.61 percent, and Alphabet's Class A shares represent 3.24 percent. These five positions collectively account for 25.22 percent of the fund.

When both of Alphabet's share classes are included, the top five companies hold nearly 28 percent of every dollar invested in the fund. Broadcom, a chip designer, sits as the sixth largest holding at 2.77 percent. Memory manufacturer Micron climbed into the fund's top 10 by the end of June, representing 2.01 percent of assets, propelled by robust artificial intelligence demand.

The fund's 10 largest positions account for 36.33 percent of its total assets. For an investor with a $10,000 allocation, approximately $3,633 is directed into these 10 companies. The remaining $6,367 spreads across the other 510 positions, averaging about 0.12 percent each, or roughly $12 per position.

The so-called Magnificent 7—Alphabet, Amazon, Apple, Meta, Microsoft, Nvidia, and Tesla—now comprise more than 40 percent of the S&P 500 by market capitalization. In the Nasdaq-100, the five largest companies account for 55.4 percent of the index.

Index investors are making a concentrated bet on a handful of AI-linked technology giants. The fund's performance hinges heavily on these holdings.