Investors combining Vanguard Total Stock Market ETF (VTI) and Vanguard Growth ETF (VUG) in equal measure may find nearly half of their assets concentrated in a handful of stocks. As of recent data, nine shared holdings account for approximately 47.6% of such a portfolio, raising questions about diversification in popular index funds.
On Monday, those overlapping names dragged both funds lower. VUG fell about 1.2% by early afternoon, while VTI and the Vanguard S&P 500 ETF (VOO) each declined roughly 0.7%. The Vanguard High Dividend Yield ETF (VYM) edged down 0.2%, showing relative resilience.
The concentration stems from market-cap weighting. At the end of May, VTI's top ten holdings represented 34.6% of its assets, while VOO's top ten accounted for 39.2%. VUG was even more top-heavy, with its top ten making up 64.6% of the fund. Three mega-cap stocks—Nvidia (NVDA), Apple (AAPL), and Microsoft (MSFT)—alone would represent roughly 26% of a 50-50 VTI/VUG portfolio.
This overlap has been easy to overlook amid strong returns. As of July 9, VOO posted a 10-year average annual return of 15.36%, while VTI returned 14.90%. VOO recently became the first ETF to surpass $1 trillion in assets, reflecting investor appetite for low-cost broad market exposure, according to Todd Rosenbluth of VettaFi.
Monday's market action provided a real-time test. Rising U.S.-Iran tensions pushed crude futures up about 5%, while tech led the S&P 500 lower, falling 1.4%. The Philadelphia semiconductor index dropped 3.7% near midday. "A broader pullback in risk taking," noted Brian Mulberry of Zacks Investment Management.
VYM offered a contrast, with only one top-ten name—Broadcom (AVGO)—shared with VTI. Its yield of roughly 2.3% and tilt toward financials (about 20% of assets) and energy (9%) provide a different risk profile. However, VYM remains vulnerable to credit losses or oil price declines, while VUG could rebound if AI investment and chip stocks recover. The 10-year Treasury yield hovering near 4.6%—roughly double VYM's dividend yield—highlights the equity risk income-seeking investors still take.
Looking ahead, investors face a busy week with U.S. inflation data, Fed Chair Kevin Warsh's testimony, producer prices, retail sales, and big bank earnings. S&P 500 second-quarter profits are expected to climb 23.7%. "It just seems like a lot of factors coming to a head all at once," said Michael Reynolds of Glenmede.
The takeaway: ETF labels may be simple, but portfolio stories are not. VTI covers thousands of stocks, VOO mirrors many of the same top names, and VUG amplifies that concentration. VYM shifts exposure but doesn't eliminate risk. Simply adding more tickers does not guarantee diversification.
