VOO: Vanguard S&P 500 ETF Guide (2026)

VOO is a passively-managed exchange-traded fund issued by Vanguard that tracks the S&P 500 index, the 500 largest US-listed companies, weighted by market capitalization. When you buy one share of VOO, you're effectively buying a tiny slice of all ~503 companies in the S&P 500 (the index occasionally holds slightly more than 500 because of multiple share classes).

The pitch is simple: rather than picking which large-cap US stocks will outperform, you own all of them, and you ride the index. Historically, beating the S&P 500 over 20+ year periods has been one of the hardest things to do in investing, which is why VOO is the most-held ETF among long-term US investors.

VOO is market-cap weighted, so the largest US companies dominate the top of the fund. As of early 2026, the top 10 holdings account for roughly 35% of total assets:

The remaining ~493 holdings make up the other ~65% of the fund, with weights decreasing roughly logarithmically down to the smallest constituents (which sit at less than 0.01% each). Sector mix is approximately 31% technology, 13% financials, 13% healthcare, 11% consumer discretionary, with the rest spread across industrials, communication services, consumer staples, energy, utilities, materials, and real estate.

All three track the same index, so returns are nearly identical. The differences are in fees, liquidity, and provider ecosystem:

• VOO (Vanguard): 0.03% expense ratio. The most-held S&P 500 ETF among long-term retail investors. Currently the largest by AUM.
• SPY (State Street): 0.0945% expense ratio. The oldest US ETF (launched 1993) and the most liquid, preferred by options traders and active strategies. More expensive for long-term holders.
• IVV (iShares / BlackRock): 0.03% expense ratio. Functionally identical to VOO at the same cost. Choice between VOO and IVV is mostly about which provider's ecosystem you prefer.

For a long-term core holding, VOO or IVV. For options strategies or short-term trading, SPY. The expense ratio gap between VOO/IVV (0.03%) and SPY (0.0945%) compounds to thousands of dollars on a six-figure position over 30 years.

VOO's performance is, by construction, the S&P 500's performance minus 0.03% in annual fees. Over the past decade, the S&P 500 has annualized roughly 13% (including dividends), well above its long-run historical average of ~10%. Whether that outperformance continues depends on factors no one can reliably predict, earnings growth, interest rates, valuation multiples, and concentration risk in the top-heavy mega-cap names.

One thing worth understanding: VOO is currently more concentrated than at most points in its history. The top 10 holdings make up ~35% of the fund, up from ~25% a decade ago. If you already own NVDA, MSFT, AAPL, GOOGL, or AMZN directly, you have meaningful overlap with VOO, worth checking before adding both to the same portfolio.

That depends on what else is in your portfolio. VOO is an excellent core holding, a single ETF that captures broad US large-cap exposure at near-zero cost. Many long-term investors run a portfolio that's 60–80% VOO (or equivalent) with the remainder in thematic satellites, international exposure, bonds, or individual conviction picks.

Where VOO falls short: it's heavily concentrated in US large-cap, so you don't get small-cap, international, or factor exposure (value, quality, momentum). If you want those, you'd pair VOO with something like VTI (broader US), VXUS (international), or sector / factor ETFs.

Walnut isn't an investment adviser and this isn't a recommendation, but in conversation, Walnut's AI can sketch portfolios that use VOO as the core plus thematic baskets you actually believe in, and tell you when there's meaningful overlap.

VOO trades on NYSE Arca during US market hours (9:30am–4:00pm ET). You can buy it through any brokerage:

• Major US brokers: Robinhood, Fidelity, Schwab, Vanguard, E*TRADE, Public, M1, Webull, all support VOO with $0 commission.
• Fractional shares: Robinhood, Fidelity, Schwab, Public, M1, Vanguard, and several others support fractional VOO purchases (as little as $1).
• Automated investing: If you want a recurring buy schedule, most brokers support it. M1 and Vanguard handle this most cleanly.

Walnut doesn't replace your broker, it sits on top of it. Connect any major broker and Walnut adds an AI layer that helps you build baskets around VOO, monitor drift against your target allocations, and rebalance with confidence.