You Bought VOO and VTI for Diversification. About 85% of Your Money Sits in the Same Stocks
Buying two broad Vanguard index funds feels like spreading your risk across the market, but the holdings inside each fund tell a very different story about where your money actually ends up.
This post may contain links from our sponsors and affiliates, and Flywheel Publishing may receive compensation for actions taken through them.
You bought the Vanguard S&P 500 ETF (NYSEARCA:VOO) because it tracks the S&P 500. Then you added the Vanguard Total Stock Market ETF (NYSEARCA:VTI) because “total market” sounded broader. Look inside both, and roughly 80% to 85% of VTI’s weight sits in the same S&P 500 names VOO already owns. Those are the same stocks twice, in slightly different wrappers, and you’re paying two funds to hold them.
What You’re Actually Paying Twice For
VOO’s sticker fee is genuinely cheap. Its June 30, 2026 semi-annual report shows fund costs of just $1.50 on a hypothetical $10,000 investment over six months, at an annualized 0.03% expense ratio. VTI carries a similarly low expense ratio. The real cost is paying that fee twice for overlapping exposure. If about 85% of VTI’s holdings are already sitting inside VOO, than your VTI position is simply a duplicate holding wearing a different label. That said, the bigger cost is the opportunity cost: account space dedicated to an exposure you already have, rather than to an asset that moves differently.
What the Fact Sheet Doesn’t Highlight
VOO holds 519 stocks as of June 30, 2026, with Information Technology at 38.0% of net assets ($1.68 billion). VTI’s roughly 3,600-name portfolio sounds far broader, but it is market-cap-weighted, so the same mega-cap S&P 500 slice dominates the top of the book. The small- and mid-cap tail adds names, not weight.
The performance gap tells you how little the “total market” tail actually contributes. Over the past year, VOO returned 17.66% against VTI’s 15.95%. Year to date, VOO is up 12.79% against VTI’s 12.32%. Over five years, VOO is up 84.21% against VTI’s 63.68%. Over ten years, VOO gained 323.61% against VTI’s 245.75%. Two funds, one dominant bet, distinguished mostly by how much drag the small-cap sleeve has added.
There is also a quiet tax angle. Two funds mean two distribution streams to reconcile each December if you hold these funds in a taxable account. Duplicate exposure also complicates tax loss harvesting, because pairing two funds that hold nearly the same book creates a gray area around IRS “substantially identical” treatment.
A Cheaper Way to Own the Same Market
If you want the S&P 500, own it once. VOO does the job at 0.03%, and a peer like SPDR Portfolio S&P 500 ETF (NYSEARCA:SPLG) offers comparable exposure at a comparable fee. If you want the total US market, own VTI and stop there. Stacking a second broad Vanguard core fund gets you almost the same thing at almost the same cost.
Real diversification comes from a sleeve that behaves differently. For example, the Vanguard Total International Stock ETF (NASDAQ:VXUS) holds companies VOO and VTI structurally exclude. The Avantis U.S. Small Cap Value ETF (NYSEARCA:AVUV) tilts toward a factor that market-cap-weighted funds underweight by design. Either one adds exposure the S&P 500 top 10 do not already dominate.
What This Means for You
Before you buy a second broad US index fund, ask one question: what does this add that my first fund does not already hold? If the real answer is “a rounding error,” the second fund is charging you to duplicate the first.
Contact [email protected] for any questions or corrections.
Ryne Mauck is an investment writer covering exchange-traded funds, retirement planning, and portfolio strategy. Through his work at 24/7 Wall St. and other investment platforms, including Seeking Alpha, he aims to provide clear, research-driven insights that help investors make more informed decisions while maintaining a long-term approach to investing.
Ryne holds a B.Sc. in Finance and an M.A. in Political Science. He is a formerly registered Municipal Advisor Representative and has passed the Series 50, Series 63, and Series 65 exams. His articles are not intended to be, nor should they be interpreted as, financial advice.
