Explore how sector focus and portfolio breadth set these two growth ETFs apart for investors weighing diversification against volatility.
Robert Izquierdo, The Motley Fool
4 min read
The Vanguard Mega Cap Growth ETF (NYSEMKT:MGK) and iShares Russell 2000 Growth ETF (NYSEMKT:IWO) differ sharply on cost, sector exposure, and risk profile, with MGK targeting the largest U.S. growth stocks and IWO offering access to a sprawling basket of small-cap growth companies.
Both funds aim to capture U.S. growth equities, but their approaches and underlying portfolios are worlds apart. This comparison lays out how MGK’s mega-cap tech concentration stacks up against IWO’s broad small-cap exposure, helping investors weigh cost, performance, diversification, and volatility.
| Metric | MGK | IWO |
|---|---|---|
| Issuer | Vanguard | IShares |
| Expense ratio | 0.05% | 0.24% |
| 1-yr return (as of 2026-04-16) | 40.8% | 46.5% |
| Dividend yield | 0.4% | 0.5% |
| Beta | 1.17 | 1.46 |
| AUM | $27.9 billion | $12.2 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.
MGK is meaningfully more affordable, with a 0.05% expense ratio versus IWO’s 0.24%. IWO edges out MGK on dividend yield, offering a 0.5% payout compared to MGK’s 0.4%.
| Metric | MGK | IWO |
|---|---|---|
| Max drawdown (5 y) | -36.02% | -40.51% |
| Growth of $1,000 over 5 years | $1,895 | $1,198 |
IWO tracks a small-cap growth universe, holding over 1,100 names and spreading assets primarily across healthcare (25%), technology (22%), and industrials (21%). Its largest positions, such as Bloom Energy Class A (NYSE:BE), Credo Technology Group (NASDAQ:CRDO), and Fabrinet (NYSE:FN), each account for less than 3% of assets, reflecting deep diversification. The fund has a long track record at 25.7 years.
MGK, in contrast, is a concentrated play on the U.S. mega-cap growth space, with technology, communication services, and consumer cyclical stocks dominating the portfolio. Its top holdings — Nvidia (NASDAQ:NVDA), Apple (NASDAQ:AAPL), and Microsoft (NASDAQ:MSFT) — make up a far larger portion of assets, highlighting a heavy tilt toward the largest tech names.
For more guidance on ETF investing, check out the full guide at this link.
Choosing between the Vanguard Mega Cap Growth ETF (MGK) and iShares Russell 2000 Growth ETF (IWO) comes down to individual investor strategies and goals. MGK grants exposure to the biggest companies in the U.S. stock market while IWO focuses on the smallest.
MGK is for those who want to invest in giants such as Nvidia and Microsoft. As a result, the ETF offers more stability and reduced risk. This is illustrated in MGK’s lower beta and max drawdown over the last five years. Other advantages include MGK’s low expense ratio of 0.05% and larger AUM of nearly $30 billion, which offers greater liquidity for those interested in more active trading.