The S&P 500 (NYSE:SPY) has a concentration problem. Its top 10 holdings command 39% of the portfolio, with mega-cap tech names like NVIDIA (NASDAQ:NVDA), Apple (NASDAQ:AAPL), and Microsoft (NASDAQ:MSFT) alone accounting for over 20%. Information Technology represents 34% of the fund, and when combined with Communication Services, Big Tech exposure pushes past 44%. For investors seeking broader diversification without abandoning U.S. equity growth, JPMorgan BetaBuilders U.S. Mid Cap Equity ETF (NYSE:BBMC) offers a compelling alternative.
True Diversification Across 200+ Mid-Caps
BBMC spreads capital across more than 200 mid-cap companies with no single holding exceeding 0.73%. Its top 10 positions represent just 5% of assets, a stark contrast to SPY’s 39% concentration. This structure eliminates single-stock risk while maintaining exposure to established businesses with room to grow.
The sector allocation reflects a balanced approach. Industrials lead at 20%, followed by Financials at 15%, and Information Technology at just 13%. Healthcare, Consumer Discretionary, Materials, and Energy all receive meaningful representation. This diversification matters when mega-cap tech faces valuation pressure or when economic cycles favor different sectors.
The Mid-Cap Sweet Spot
Mid-cap companies occupy a unique position. They’ve proven their business models and achieved scale, yet retain significant growth potential without the valuation premiums attached to mega-caps. BBMC’s holdings include established names like Jabil (NYSE:JBL), Williams-Sonoma (NYSE:WSM), and Ciena (NYSE:CIEN), companies with pricing power and market share but trading at more reasonable multiples than the Magnificent Seven.
The fund’s 0.07% expense ratio is exceptionally low for this exposure, costing just $7 annually per $10,000 invested. With 13% portfolio turnover, BBMC maintains tax efficiency while rebalancing to capture mid-cap opportunities.
Recent Performance Context
SPY returned 18% year-to-date through late December 2025, outpacing BBMC’s 14%. However, this outperformance stems from the very concentration risk that diversified investors may wish to avoid.
Who Should Avoid BBMC
Investors seeking maximum short-term momentum should stick with mega-cap tech concentration. Those requiring high dividend income will find BBMC’s 1% yield insufficient. The fund also lacks the brand recognition and liquidity of SPY, with $2 billion in assets versus SPY’s $700 billion.
Alternative: Vanguard Mid-Cap ETF (NYSE:VO)
VO offers similar diversification with $80 billion in assets and deeper liquidity. Its 0.04% expense ratio undercuts BBMC slightly, though both remain exceptionally low-cost. VO tracks a broader mid-cap index, while BBMC employs factor tilts that may enhance returns during certain market conditions.
BBMC delivers genuine diversification away from mega-cap tech concentration, but investors must accept potentially lagging returns during periods when the largest stocks dominate market gains.