Investing in the S&P 500: ETFs, Costs, and Portfolio Role

ETF Vehicles That Track This Index

Four major ETFs give US investors direct exposure to the S&P 500 Index. Each holds all 500 constituents in their market-cap-weighted proportions, but they differ meaningfully in cost, trading characteristics, and fund structure.

SPY (SPDR S&P 500 ETF Trust) launched in 1993 as the first US-listed ETF and remains the most heavily traded equity ETF in the world by dollar volume. SPY is structured as a Unit Investment Trust, which means it cannot reinvest dividends between distribution dates, a minor drag compared to open-end funds. Its AUM exceeds $500 billion. The high trading volume and tight bid-ask spreads make SPY the instrument of choice for institutional traders, options desks, and anyone moving large notional amounts in and out quickly.

IVV (iShares Core S&P 500 ETF) from BlackRock is structured as an open-end mutual fund converted to ETF form, which allows it to reinvest dividends until they are distributed quarterly. AUM is over $400 billion. IVV and VOO are the preferred vehicles for long-term buy-and-hold investors because their lower expense ratio compounded over decades produces meaningfully more wealth than SPY.

VOO (Vanguard S&P 500 ETF) is the share class of Vanguard's S&P 500 Index mutual fund (VFIAX). Vanguard's unique ownership structure, where fund investors own the company, has historically enabled it to pass cost savings to shareholders. VOO AUM exceeds $500 billion. Like IVV, VOO pays quarterly dividends and can reinvest dividends between distribution dates.

SPLG (SPDR Portfolio S&P 500 ETF) charges the lowest expense ratio of any major S&P 500 ETF at 0.02% per year as of 2026. SPLG is also open-end structured. AUM is smaller than the three larger peers, so bid-ask spreads are slightly wider, though still narrow enough to be inconsequential for most long-term investors executing occasional lump-sum or dollar-cost-averaging purchases.

Expense Ratios and Costs

Expense ratios are the single most reliable predictor of long-term relative performance among funds tracking the same index. Because all four funds hold the same 500 stocks, the difference in net return is essentially the difference in expense ratio.

To understand the practical impact: a $10,000 investment earning 7% annually before fees would grow to approximately $74,872 over 30 years with a 0.02% expense ratio versus approximately $73,297 with a 0.0945% expense ratio. That difference of roughly $1,575 on a $10,000 initial investment illustrates why long-term investors favor SPLG, IVV, or VOO over SPY for core portfolio positions. For traders who enter and exit positions frequently, SPY's liquidity premium can more than offset the cost difference through tighter spreads on large transactions.

Beyond the expense ratio, investors in taxable accounts should factor in the bid-ask spread on each purchase and sale. All four funds are liquid enough that the spread is typically less than one basis point for small and mid-size retail orders.

Portfolio Role and Benchmarking

The S&P 500 functions as the most widely referenced equity benchmark in US investing. Financial advisers, pension funds, endowments, and individual investors routinely compare their portfolio returns to the S&P 500 total return index, which assumes dividends are reinvested. Many brokerages display this as the default comparison in portfolio performance views.

In a core-satellite portfolio strategy, a large-cap US equity position through an S&P 500 ETF typically serves as the core. The satellite portion might include international equities, small-cap exposure, sector ETFs, individual stocks, or alternative strategies. The core position provides broad US large-cap diversification at near-zero cost, while the satellite positions express specific views or seek additional diversification.

The case for passive S&P 500 exposure is well-supported by long-term performance data. The SPIVA US Scorecard, published semi-annually by S&P Global, consistently finds that the majority of actively managed US large-cap funds underperform the S&P 500 over 10- and 15-year periods after fees. This is not a new finding: the margin of underperformance has been relatively stable across multiple market cycles. The primary reasons are the compounding effect of management fees, the difficulty of consistently identifying mispriced securities in a large, well-covered market, and the tax drag from active turnover in taxable accounts.

For investors benchmarking their own stock-picking or active strategies, the relevant comparison is the S&P 500 total return index (ticker ^SP500TR or accessible through most major data providers), not the price index alone. Omitting dividends from the comparison significantly understates the index's total return, especially over multi-decade periods when dividends have been reinvested.

Tax Considerations for US Investors

S&P 500 ETFs are among the most tax-efficient equity investment vehicles available to US investors. The ETF creation/redemption mechanism allows fund managers to remove low-basis shares from the fund by delivering them in-kind to authorized participants during redemptions, without triggering a taxable sale inside the fund. This mechanism has allowed IVV and VOO to distribute zero capital gains to shareholders for many consecutive years.

Dividends from S&P 500 ETFs are predominantly qualified dividends. Qualified dividends are taxed at 0%, 15%, or 20% depending on the investor's taxable income, rather than at ordinary income rates. To qualify, the underlying dividend must be paid by a US corporation or qualifying foreign corporation, and the investor must hold the ETF shares for more than 60 days during the 121-day window surrounding the ex-dividend date. In practice, long-term holders of SPY, IVV, VOO, or SPLG receive mostly qualified dividends, reported on their 1099-DIV as qualified dividend income.

Tax-loss harvesting is a common strategy among holders of S&P 500 ETFs in taxable accounts. Because SPY, IVV, VOO, and SPLG all track the same index but are issued by different fund companies, selling one at a loss and immediately purchasing another is generally considered a valid way to realize a loss without triggering the wash-sale rule, since these are different securities. Investors should consult a tax professional before executing this strategy, as IRS guidance does not explicitly bless specific fund substitutions and positions can change.

Dividend reinvestment plans (DRIPs) in taxable brokerage accounts create additional cost basis lots with each reinvestment. Over many years this means tracking dozens of small lots, which modern brokerage platforms handle automatically using average cost or specific lot identification. Investors using specific lot identification should keep records of purchases to maximize tax-loss harvesting opportunities in the future.

For investors deciding between holding S&P 500 ETFs in taxable versus tax-advantaged accounts, the ETF's high tax efficiency means the tax cost of holding in a taxable account is lower than for most other equity categories. That said, tax-advantaged space (IRA, 401(k), HSA) is valuable and is generally prioritized for higher-turnover or higher-yielding investments first.