Three of the largest ETFs in the world - VOO, SPY, and IVV - track the exact same underlying index: the S&P 500. Their actual holdings, sector weightings, and index-level performance are effectively identical, which raises a genuine question for anyone comparing them: if the investment inside the wrapper is the same, what’s actually different, and does it matter enough to pick one over the others?
What Each Fund Actually Is
SPY (SPDR S&P 500 ETF Trust) was the first US ETF ever launched, in 1993, and remains the most heavily traded ETF in the world by daily volume. It’s structured as a unit investment trust (UIT), a legally distinct wrapper from the standard open-end fund structure used by most modern ETFs, including its two main competitors.
VOO (Vanguard S&P 500 ETF) is Vanguard’s S&P 500 offering, structured as a standard open-end fund, and carries an expense ratio of 0.03% - Vanguard’s broader fee structure across its index fund lineup has consistently been among the lowest in the industry.
IVV (iShares Core S&P 500 ETF) is BlackRock/iShares’ offering, also structured as a standard open-end fund, matching VOO’s 0.03% expense ratio and meaningfully below SPY’s.
The Real Difference: Cost, Compounded Over Time
VOO and IVV both carry meaningfully lower expense ratios than SPY: 0.03% for VOO and IVV versus approximately 0.0945% for SPY, a gap of roughly $6.45 a year per $10,000 invested. The specific numbers have shifted over the years as all three providers have periodically adjusted pricing, so confirm the current figures directly with each provider rather than treating these as permanently fixed, but the ordering (VOO and IVV below SPY) has been a consistent, structural feature of the three funds’ pricing for years.
Why this matters more than it might seem: an expense ratio difference that looks trivial as a single annual percentage compounds meaningfully over a long holding period, because it’s deducted every year, indefinitely, regardless of market performance. Consider two otherwise identical $50,000 positions held for 20 years, growing at the same 8% gross annual return, where one fund’s expense ratio runs 0.05 percentage points higher than the other. That seemingly tiny annual gap compounds to a meaningfully different ending balance over two decades - not because either fund performed differently, but purely because a slightly larger annual slice was deducted from one of them, year after year, compounding against the investor rather than for them.
Why SPY still commands enormous trading volume despite the higher cost: its status as the original, most heavily traded S&P 500 ETF makes it the default choice for institutional traders, market makers, and options traders who prioritize maximum liquidity and the deepest options market over the small ongoing cost difference - the same dynamic covered in our QQQ vs QQQM comparison regarding QQQ’s continued dominance despite QQQM’s lower cost. Trading volume and expense ratio serve genuinely different types of investors, and SPY’s volume reflects its role as a trading vehicle as much as an investment vehicle.
Liquidity and Options Markets
SPY has the deepest, most liquid options market of the three by a wide margin - a direct consequence of decades as the default institutional S&P 500 trading vehicle, with tighter bid-ask spreads and more available strikes and expirations than either VOO or IVV’s options markets currently offer. For an investor planning to run options income strategies (covered throughout our options-income category) against an S&P 500 position specifically, SPY’s superior options liquidity can be worth its higher expense ratio, similar to the QQQ-vs-QQQM liquidity trade-off covered in our strategies content.
For a pure buy-and-hold position with no options overlay, VOO or IVV’s lower cost wins with no meaningful downside, since the underlying index exposure delivered to the investor is identical to SPY’s - there’s no performance or diversification trade-off being made, only a cost trade-off.
The UIT Structure - What It Actually Means in Practice
SPY’s unit investment trust structure imposes a specific, real constraint that VOO and IVV don’t share: it cannot reinvest dividends internally between distribution dates. A standard open-end fund can reinvest dividend income it receives from underlying holdings immediately, letting that cash continue generating index exposure until the fund’s own distribution date. SPY, as a UIT, is legally required to hold dividend income as uninvested cash until its quarterly distribution, creating a small, structural “cash drag” that VOO and IVV don’t experience in the same way.
How much this actually costs an investor is a genuinely modest amount in most years - dividend yields on the S&P 500 are typically in the low single digits annually, and the drag only applies to the brief holding period between receipt and distribution, not the full dividend amount for a full year. It’s real, structurally different, and worth knowing about, but it’s a smaller practical factor than the expense ratio difference for most holding periods.
Securities lending revenue is another structural difference worth naming. All three funds may lend out a portion of their underlying holdings to short sellers and other market participants for a fee, and this lending revenue can partially offset the fund’s own costs - the specific lending programs, revenue-sharing arrangements, and how much of that revenue benefits shareholders versus the fund manager vary by provider and aren’t always fully transparent to retail investors, making it a difficult factor to compare precisely across the three funds without direct disclosure from each provider.
Tracking the Same Index Doesn’t Guarantee Identical Returns
All three funds aim to replicate the S&P 500’s performance, but none of them do so with mathematically perfect precision. Small tracking differences arise from each fund’s expense ratio, cash drag (particularly for SPY), securities lending revenue, and the specific mechanics of how each fund handles index reconstitution (when companies are added to or removed from the S&P 500). Over any given year, these funds’ actual returns can differ from each other, and from the index itself, by small amounts - generally in a range close to the expense ratio differential, though not perfectly predictable in advance.
VOO vs SPY vs IVV in Practical Terms
If your plan is pure buy-and-hold with no options trading: VOO or IVV deliver identical S&P 500 exposure to SPY at a lower ongoing cost, with the cost advantage compounding meaningfully over a long holding period - choose between VOO and IVV based on which broker’s platform you’re using or minor preference, since their expense ratios are typically close enough that the choice between them matters far less than choosing either over SPY for a pure buy-and-hold strategy.
If you plan to run options strategies against your S&P 500 position: SPY’s superior liquidity - tighter spreads, more strikes, deeper open interest - is likely worth the higher expense ratio, since options-strategy costs from wide bid-ask spreads on a less liquid underlying can easily exceed the annual expense ratio gap.
If you’re unsure which category you fall into: default to VOO or IVV. Most individual investors on this site are pursuing long-term, buy-and-hold exposure rather than active options overlay strategies, and the lower-cost funds serve that use case without any offsetting downside.
Frequently Asked Questions
Does the choice between VOO, SPY, and IVV affect my US dividend withholding tax as a non-resident? No - all three are US-domiciled funds subject to the same NRA dividend withholding framework covered in our main dividend withholding guide, since the withholding treatment depends on the fund’s domicile and your tax status, not on which specific S&P 500 ETF you hold.
Can I hold all three at once, or does that create unnecessary overlap? Holding more than one of these funds simultaneously doesn’t add diversification value, since they track the identical index - it would only make sense as a deliberate tax-lot management technique (for instance, harvesting a loss in one while maintaining S&P 500 exposure through another to avoid a wash sale under US rules), not as a genuine portfolio diversification move.
Is IVV meaningfully different from VOO in any way beyond expense ratio? The two are close enough in structure and cost that the practical difference for most investors is minimal - both are standard open-end funds from major providers with competitive, similar expense ratios. Provider-specific factors like securities lending programs or platform availability at your specific broker are more likely to be the deciding factor than any inherent difference in the funds themselves.
For EU/UK investors, is there a UCITS equivalent to VOO, SPY, or IVV? Yes - PRIIPs regulation blocks direct retail access to all three US-domiciled funds for EU/UK investors, requiring an Irish-domiciled UCITS equivalent instead, covered in detail in our UCITS vs US-domiciled comparison.
Where VOO vs SPY vs IVV Leaves You
VOO, SPY, and IVV are functionally the same investment - identical index, identical underlying holdings, near-identical performance - differentiated by cost (VOO and IVV structurally lower) and liquidity (SPY structurally deeper, particularly for options). Choose based on whether you’re optimizing for cost as a long-term buy-and-hold investor, in which case VOO or IVV wins with no real downside, or liquidity as an active options trader, in which case SPY’s deeper market can justify its higher ongoing cost.
This explains VOO vs SPY vs IVV; it does not advise you on what to do about it. The compounding example uses hypothetical figures to illustrate the mechanic described, not a performance forecast or guarantee. Expense ratios, securities lending programs, and fund structures can change - confirm current figures directly with each fund provider before investing.
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- US Dividend Withholding Tax for Foreign Investors
