Vanguard’s $94 Billion Mid Cap ETF Is Steadily Outperforming the S&P 500 Using a Fifty-Year-Old Approach

May 20, 2026

quick read

The Vanguard Midcap ETF (VO) manages $94 billion in assets, has an expense ratio of just 0.04%, and tracks over 300 U.S. firms with market valuations between $2 billion and $20 billion. Notable companies include Williams-Sonoma (WSM) at $20.22 billion and Builders First Source (BLDR) at $7.14 billion. Meanwhile, the SPDR S&P 500 ETF (SPY) leans heavily on its top three holdings, which account for about 19% of its total assets. This concentration leaves investors without a significant mid-cap presence, despite research indicating that size can be a key source of return.
Over the last decade, VO has achieved a return of 195%, compared to SPY’s 257%. Although it has underperformed during the AI-driven rally since 2016, its heightened economic sensitivity (beta of 1.49) and lower fees compared to other mid-cap funds make it appealing for diversification, albeit at the cost of a strong focus on AI investment.
Interestingly, analysts who highlighted NVIDIA back in 2010 listed only their top 10 stocks, omitting the Vanguard Midcap ETF.

Many retirees relying on S&P 500 index funds find their portfolios heavily weighted in mega-cap tech stocks, leaving them with minimal exposure to mid-cap companies. This gap is where the Vanguard Midcap ETF steps in, effectively infusing the middle tier of market cap into portfolios, drawing from decades of research on size factors.

The role VO was created to play

VO tracks the CRSP US Mid Cap Index, which includes companies with market capitalizations from $2 billion to $20 billion. Names like Williams-Sonoma, with its market cap close to $20.22 billion, or Builder’s First Source at $7.14 billion, are great examples. These companies are established and profitable, but still have potential for growth that can outpace larger firms like those worth $3 trillion. By investing in a few hundred stocks weighted by market cap, you can also enjoy an almost 1.5% distribution yield.

It’s worth noting that the SPDR S&P 500 ETF has become more concentrated. Its three largest holdings—NVIDIA, Apple, and Microsoft—constitute about 19% of the fund. Investors relying solely on SPY alongside bond funds effectively yield no exposure to the size categories recognized as structural return sources in over 50 years of factor research.

Analysts who identified NVIDIA in 2010 listed only their top 10 stocks, and strangely, the Vanguard Midcap ETF was not one of them.

This infographic lays out an overview of the Vanguard Mid-Cap ETF (VO), highlighting its exposure to mid-cap stocks along with its role in diversification and potential growth, as well as the trade-offs that come with such a strategy.

Test promises against reality

For a decade now, mid-cap stocks haven’t quite kept pace with their large-cap counterparts. Over the past 10 years, VO has delivered about 195%, against SPY’s 257%. A similar trend emerged over the previous five years: about 43% for VO versus 77% for SPY. The most recent year saw VO up about 13%, while SPY gained 23%.

The idea that mid-cap stocks are quietly outperforming the index doesn’t seem to hold water within this timeframe. While size premiums do exist in long-term academic studies, the current AI-driven mega-cap surge continues to overshadow the market since 2016. Within mid-cap stocks, there’s a fair amount of variation; for instance, Williams-Sonoma managed an impressive 768% growth over the last decade, while Builders First Source clocked in around 470% but saw a 44% downturn recently due to housing market challenges. VO, however, smooths out these inconsistencies by maintaining a diverse portfolio of hundreds of names.

What do you give up and what do you gain?

Investors considering mid-cap allocations must weigh three key trade-offs. This sector tends to exhibit much higher economic sensitivity compared to large-cap benchmarks. Take Williams-Sonoma and Builders First Source; both have a beta of 1.49, indicating they generally amplify larger market trends—both up and down. Also, diving into mid-caps means stepping away from the focus on AI that underpins the S&P 500 index. Moreover, the baseline dividend yield tends to be modest, which suggests VO is more geared for growth than income.

VO sticks to a low fee of just 0.04%, making it significantly less expensive than the SPY’s 0.0945% expense ratio. Competing entities like the iShares Core S&P Midcap ETF and SPDR S&P Midcap 400 take different benchmarks and employ stringent quality measures, leading to varying performance profiles compared to Vanguard’s broader index.