Markets have been turbulent and uncertainty have been high. But one of the biggest stories in the ETF market this year has been the nonstop impressive asset-gathering pace of the Vanguard S&P 500 ETF (VOO ).
The largest ETF in the market — VOO — is now a $608 billion ETF (as of May 21). So far in 2025, this fund has picked up $65 billion in net new assets. That’s a pace never before seen. It’s noteworthy to highlight that VOO’s prowess in the asset-gathering race has only been picking up momentum. The fund already broke records in 2024, with net inflows of about $116 billion. That’s more than any other ETF ever in a calendar year.
Whether this demand has been driven by recent market weakness, which has reset historically high valuations and high concentration in the index, or by confidence in U.S. market and economic resilience despite high policy uncertainty, the fact remains that appetite for VOO and S&P 500 exposure are high.
VOO has unique appeal tied to Vanguard’s brand strength and its ultra-low cost — only 3 basis points — for a portfolio tied to the S&P 500. But VOO is only one of the many index-based (passive) S&P 500 ETFs.
In truth, there are many ways to have exposure to the S&P 500 in a passive, index-based ETF. Consider five unique examples of strategies that own the same mix of 500 companies (504 holdings due to share classes).
1. SPDR S&P 500 ETF Trust (SPY ): The original market-capitalization-weighted ETF
SPY was the original U.S.-listed ETF, and the first S&P 500 fund. It owns the 500 largest companies in the U.S. in a market-capitalization weighted portfolio. It’s widely seen as the proxy for the U.S. stock market today.
Since its arrival in 1993, many other me-too S&P 500 ETFs have followed, including a competing fund from State Street Global Advisors, the SPDR Portfolio S&P 500 ETF (SPLG). These funds are all offering the same type of passive, market-capitalization exposure to the benchmark, but at varying fee structures and with different liquidity profiles. For example, SPLG is identical to SPY and offered by the same provider, but for a much lower fee of 0.02%. SPY costs 0.0945% in expense ratio, or roughly $9 per $10,000 invested. SPLG is also about a tenth of the size of SPY, and at least 10x less liquid.
SPY has about $600 billion in total assets, and until very recently, it was the largest ETF in the market by assets. That crown has moved to competing VOO, which has been on a massive asset gathering haul, and it’s now a $608 billion fund (as of May 21). VOO has picked up $65 billion in net inflows in 2025 alone.
But SPY remains the liquidity maven. Just earlier this year, the fund traded more than $100 billion in volume in a single day, setting a record for all ETFs.
SPY currently holds technology as its largest sector allocation, representing about 30% of the overall portfolio. Financials comes in at 14% weighting, with consumer discretionary and communications services each at about 10%. These sector exposures change as the weight of underlying holdings change based on market capitalization.
2. Invesco S&P 500 Equal Weight ETF (RSP ): The equal-weighted approach
RSP holds all 500 companies in the S&P 500 benchmark but assigns an equal weight to each of them. That equal weighting feature aims to mitigate single-stock concentration risk that can exist in market capitalization-weighted portfolios.
It’s a simple-to-understand approach that overtime delivers similar exposure in terms of company names, but vastly different return profile because smaller companies in the S&P 500 carry more weight in this strategy vs. a traditional market-cap approach, so the portfolio overall tilts to smaller cap names. Equal weighting also changes the overall sector exposures. Technology, for example, snags only about 14% of RSP’s sector exposure, or roughly half of the weight seen in SPY.
3. Tema S&P 500 Historical Weight ETF (DSPY): The historical-weighted innovation
DSPY is a relatively young fund, and one that set out to innovate S&P 500 access with a novel weighting scheme in a passive approach. DSPY owns the same 500 companies in the index, but assigns to each of them what it calls “historical weight” based on trailing 35-year data.
Tema defines historical weight as “the average weight of each S&P 500 position on a monthly basis since December 29, 1989.” The strategy looks back at the basket of stocks, calculates how much the top holding represented, on average, in the past 35 or so years, and assigns that weight to the current top holding of the S&P 500.
DSPY’s current top holding represents 3.6% of the total portfolio – half the weight of SPY’s current top holding.
The fund goes on to apply that math to each of the 500 holdings. The end result is a portfolio that looks to tackle concentration risk found in market capitalization strategies, especially in the current environment following the Mag 7 phenomenon when the S&P 500 became extremely top heavy.
But by design, the strategy stays largely aligned with the S&P 500’s sector make-up because DSPY focuses on single stock allocation by portfolio position, and not my sector membership.
The Fund then reflects the historical average weight of position 1 to position 500 of the S&P 500, applied to the current constituents.
4. Invesco S&P 500 Revenue ETF (RWL ): The revenue-weighted approach
RWL offers another unique take on the same basket of 500 stocks comprising the S&P 500. The portfolio weights the stocks by revenues.
The strategy looks at trailing one-year (or previous four quarters) of a company’s revenues. It then takes that total sum and divides that by the total revenue of all S&P 500 stocks. That results in a ranking of the highest revenue-generating companies relative to its large-cap peers. RWL takes it another step and caps single-stock exposure at 5%.
The end result in the current market environment is a portfolio that tilts toward large-cap value. The biggest holdings are Walmart and Amazon. RWL also has dramatically different sector exposures relative to the market-cap S&P 500. Technology is only 11% right now.
5. GammaRoad Market Navigation ETF (GMMA): The defensive S&P 500 approach
GMMA is a new fund, having launched in late 2024. The strategy relies on three measures of risk — fundamental, behavioral, and trend-based — to determine its level of exposure to the S&P 500.
The strategy toggles between S&P 500 and T-bills depending on how bullish or bearish its risk indicators are. On an average year, the fund will rebalance its allocation between the two asset classes around six times. At its most defensive, GMMA is 100% allocated to T-bills. At its most bullish, the fund is 125% allocated to S&P 500 with a little help from leverage.
That extra juice at the top is one of its unique features relative to other defensive equity strategies like defined outcome and hedged equity strategies. That’s because it not only removes any cap from upside capture, it magnifies gains in bull markets.
GMMA is currently two-thirds allocated to T-bills and one-third to the S&P 500. That’s clearly a defensive posture. But it’s a more bullish stance than last week when the fund was entirely tied to T-bills. GMMA rebalanced its portfolio this past Monday.
Final Thought
There are many ways to own the S&P 500 beyond the five examples shared here. You can choose a leveraged approach, or a buffered approach, a factor portfolio, or even an actively managed strategy, among others. As an ETF investor, it’s exciting to see that innovation continues to break new ground and broaden market access.
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