The Vanguard Mega Cap Growth ETF (MGK +2.61%) and the iShares Russell 2000 Growth ETF (IWO +0.50%) differ sharply by cost, portfolio makeup, and risk profile.
MGK aims to provide broad exposure to the largest U.S. growth companies, tracking the CRSP US Mega Cap Growth Index, while IWO tracks small-cap stocks with growth characteristics.
This comparison explores how their costs, performance, sector exposure, and risk metrics stack up for investors seeking growth-oriented ETFs.
Snapshot (cost & size)
| Metric | MGK | IWO |
|---|---|---|
| Issuer | Vanguard | iShares |
| Expense ratio | 0.05% | 0.24% |
| 1-yr return (as of March 25, 2026) | 15.07% | 17.75% |
| Dividend yield | 0.37% | 0.54% |
| Beta (5Y monthly) | 1.21 | 1.45 |
| AUM | $29.3 billion | $13.1 billion |
Beta measures price volatility relative to the S&P 500; beta is calculated from five-year monthly returns. The 1-yr return represents total return over the trailing 12 months.
IWO is more costly in terms of fees, with a significantly higher expense ratio. However, it also offers a higher dividend yield than MGK, which may appeal to investors seeking a modest income boost alongside growth potential.
Performance & risk comparison
| Metric | MGK | IWO |
|---|---|---|
| Max drawdown (5 y) | -36.01% | -42.02% |
| Growth of $1,000 over 5 years (total returns) | $1,879 | $1,133 |
What's inside
IWO holds over 1,100 stocks and leans heavily into industrials, healthcare, and technology sectors. Its top holdings — Bloom Energy, Fabrinet, and Credo Technology Group — account for a small percentage of the portfolio.
MGK, in contrast, is concentrated in large-cap technology, communication services, and consumer cyclicals industries, with only 60 holdings. Its top positions include Nvidia, Apple, and Microsoft, reflecting a strong tilt toward mega-cap tech. This focus may result in different performance patterns, especially during periods of tech sector volatility.
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What this means for investors
MGK and IWO take significantly different approaches to U.S. equities. While MGK focuses on mega-cap growth stocks, IWO targets small-cap stocks with growth potential.
Small-cap stocks can be more volatile than their industry-leading counterparts, as seen with IWO’s higher beta and steeper max drawdown — signalling larger price swings in recent years.
That said, IWO has an edge with its substantial diversification. IWO holds over 1,100 stocks, while MGK only contains 60. Also, while IWO’s top three holdings make up less than 5% of total assets, MGK’s top three stocks account for more than one-third of the overall portfolio.
This makes MGK more vulnerable to volatility within the tech sector. If Nvidia, Apple, and Microsoft are hit hard during a downturn, it could significantly affect MGK’s performance. While IWO is still susceptible to turbulence in the small-cap market, its extensive diversification can help mitigate single-stock risk.
Neither ETF is necessarily the better buy, as the right fund for you will depend on your priorities and goals. If you’re looking for heavy exposure to mega-cap tech giants, MGK may fit your needs. For investors seeking more diversification and access to smaller companies with growth potential, IWO’s small-cap focus may make it a better choice.
