What Is ITOT? iShares Core S&P Total US Stock Market ETF

ITOT is the iShares Core S&P Total US Stock Market ETF, a single ticker that gives you ownership of roughly 2,500 to 3,500 US-listed stocks weighted by market capitalization. It tracks the S&P Total Market Index, which is designed to capture the entire investable US equity market: large-caps at the top, then mid-caps, then all the way down into the small-cap tail. At a 0.03% expense ratio, it is one of the cheapest equity funds in the world.

The simplest way to understand ITOT is as the iShares equivalent of Vanguard's VTI, or as VOO plus everything VOO leaves out. The top of the fund mirrors the S&P 500 because cap-weighting dominates, so the same mega-caps lead. The difference is the thousands of mid- and small-cap names below the S&P 500 line that ITOT adds and a large-cap fund does not. In one purchase you own essentially the whole US market.

Approximate weights as of early 2026; refresh quarterly from iShares (BlackRock)'s fund page. Each ticker links to its individual stock guide in Walnut.

Because ITOT is cap-weighted, its top holdings look almost identical to the S&P 500's: NVIDIA, Microsoft, Apple, Amazon, Meta, both Alphabet share classes, Broadcom, Berkshire Hathaway, and Tesla. The top 10 account for roughly 30% of the fund, and the largest US companies dominate the weighting the same way they do in VOO. See the top-10 table above for current weights.

The remaining holdings make up the other roughly 70%, with the very smallest constituents sitting at fractions of a basis point each. Of the total, large-caps are around 75 to 79% of the fund, mid-caps around 15 to 18%, and small-caps around 6 to 8%. That mid- and small-cap layer is the central reason to choose ITOT over a pure S&P 500 fund: it is the part of the US market a large-cap index simply does not reach.

ITOT and VTI are the two big total US market core funds, and they are functionally identical. ITOT (iShares, BlackRock, 0.03%) tracks the S&P Total Market Index; VTI (Vanguard, 0.03%) tracks the CRSP US Total Market Index. Slightly different methodologies over essentially the same universe, with returns that have tracked extremely closely. VOO (Vanguard, 0.03%) is the narrower option, holding only the S&P 500's roughly 500 large-caps, so ITOT and VTI are both VOO plus the mid- and small-cap tail.

In short: VOO is the large-cap-only core, while ITOT and VTI are the whole-US-market cores from BlackRock and Vanguard respectively. SCHB (Schwab) is a third total-market option at the same 0.03%. Because all of the total-market funds cover nearly the same universe at nearly the same cost, the choice among ITOT, VTI, and SCHB comes down mostly to which provider's ecosystem you prefer rather than any meaningful difference in what you own.

ITOT's total return comes from price appreciation across its holdings plus a dividend that yields roughly 1.3%, paid quarterly. Because the fund is dominated by the same mega-caps as the S&P 500, its returns have tracked VOO and VTI closely over long stretches. The mid- and small-cap layer adds a modest source of divergence: it can lift returns when smaller companies lead and weigh on them when the market narrows to a handful of mega-caps.

One thing to understand before buying: ITOT is a bet on the breadth of the US market rather than on any single segment of it. In years when mega-cap technology leads, ITOT and VOO behave almost identically, since those names sit at the top of both. The total-market structure tends to matter most over full cycles, when the smaller names contribute, so ITOT is best judged on long-run total return rather than any single year.

ITOT is a common single-fund core for long-term passive investors because one purchase covers the whole US equity market at near-zero cost. It also pairs naturally as the US sleeve of a broader allocation, often sitting alongside an international fund and a bond fund in a simple three-fund structure. For investors already in the iShares and BlackRock ecosystem who want US equity breadth without choosing between large, mid, and small caps, the total-market approach removes that decision entirely.

Where it falls short: ITOT is US-only, so it gives you no international exposure, and its heavy large-cap weighting means it overlaps almost completely with VOO or VTI if you already hold one. Walnut isn't an investment adviser and this isn't a recommendation, but in conversation Walnut's AI can show you how much ITOT overlaps with what you already own and where it fits as a core around your other holdings.

ITOT trades on NYSE Arca during US market hours (9:30am to 4:00pm ET) and is available commission-free at every major broker, including Robinhood, Fidelity, Schwab, Vanguard, Public, M1, and Webull. Fractional shares are supported at most modern brokers, which also lets the quarterly dividends reinvest automatically as fractional shares (DRIP), useful for a long-term core position.

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 ITOT, track how your holdings are doing against your targets, and rebalance when your allocation drifts.

ITOT is essentially VOO plus the mid- and small-cap slice of the US market, at the same 0.03% fee, and is functionally identical to VTI from a different provider. It works as a single-fund US equity core for investors in the iShares and BlackRock ecosystem who want total-market breadth, rather than as a sector or factor tilt.

Whether ITOT is worth buying today depends more on your time horizon and what you already hold than on any single call. We walk through valuation, concentration, and what would have to be true for it to outperform from here in is ITOT a buy?

ITOT yields ~1.3% as of early 2026, paid by passing through the dividends of its underlying holdings. For the payout schedule, history, and how the distributions are taxed, see ITOT dividend: yield and schedule.