The Vanguard S&P 500 ETF, often called VOO, has come very close to achieving a major historical achievement. By the end of July, the fund had amassed $979 billion in assets. This is approximately $21 billion less than the $1 trillion mark it temporarily reached in early June 2026. Despite a recent market slowdown, the fund is expected to reclaim the title of the world's largest ETF within the next few months. According to experts, this is a possibility.
Why a $21 Billion Gap Isn’t So Big
VOO has been receiving consistent investment from new and existing investors. At this rate, VOO could close the $21 billion gap within two months, even if the S&P 500 remains unchanged. This steady stream of new money is a crucial component driving the fund's potential for growth. In the first five months of 2026 alone, investors added about $69 billion to VOO. That averages out to roughly $14 billion a month in inflows, a significant figure for any investment vehicle, but especially notable for one as large as VOO.
Moreover, the performance of the S&P 500 index itself could contribute significantly. A 2% increase in the index would result in about $10 billion in new assets for VOO. Given that the index is capable of achieving such a rise in just a few days during a strong market rally, this combination of inflows and market performance could allow the fund to return to $1 trillion well before the end of the year. Even a small upward movement, combined with the consistent monthly inflows, can quickly close the gap. The S&P 500 is known to have volatility. But its ability to rebound with strong short-term rallies means that VOO has a high probability of hitting the milestone.
Why Investors Are Still Putting Money In
Investors are not being drawn to VOO by high dividend yields. In fact, the fund offers a relatively modest dividend yield of approximately 1.1%. What sets VOO apart is its extremely low expense ratio of 0.03%. For every $100,000 invested, an investor pays just $30 in annual fees. This low-cost structure makes VOO one of the most affordable S&P 500 ETFs available and a go-to choice for money managers and passive investors. Its affordability is a major reason it has captured a significant portion of the index fund market.
Since its introduction in September 2010, VOO has delivered an average annual return of about 15%. This strong performance has been bolstered, in part, by the ongoing AI-driven stock rally. This rally has helped the fund outperform many others. While this impressive rate may not be sustainable in the long run, it has been sufficient to attract consistent new investments. These investments come from those seeking exposure to the broader U.S. stock market. The combination of low fees and strong performance makes VOO particularly appealing to long-term investors.
But Not All Is Equal in the Portfolio
However, the fund's performance is not spread evenly across its holdings. Over a third of VOO’s assets are concentrated in its top 10 stocks. Among these is chipmaker Nvidia, which alone accounts for 7.5% of the fund. This concentration means that a significant downturn in the tech sector could hinder VOO's progress toward reaching $1 trillion. This downturn would particularly affect AI and growth stocks. A slump in the largest growth stocks in the S&P 500 could drag the fund down disproportionately. This could potentially delay or even prevent it from reattaining the $1 trillion milestone.
The likelihood of VOO returning to the $1 trillion mark is rooted in arithmetic rather than market forecasting. As long as the S&P 500 does not experience a major decline and the monthly inflows remain at or above $14 billion, the target becomes increasingly attainable. Even if the market remains stable, the combination of strong investor demand and the index's performance should propel the fund back to this historic benchmark. This is further supported by the fact that similar ETFs, such as the iShares Core S&P 500 ETF and the SPDR S&P 500 ETF Trust, trail VOO in assets, with $860 billion and $786 billion, respectively, as of the time VOO crossed $1 trillion.
The combination of consistent inflows and the potential for moderate market gains provides a realistic path for VOO to reach $1 trillion in assets once again, despite the challenges posed by its concentrated portfolio.