IWF vs SPY: Which ETF Is Better in 2026?
A metric-by-metric comparison of iShares Russell 1000 Growth ETF (IWF) and State Street SPDR S&P 500 ETF Trust (SPY) — both US Large Cap Growth / US Large Cap Blend funds — using ETFValuer's daily-updated rankings.
Educational content — not financial advice. Data as of July 25, 2026. ~5 minute read.
The Verdict
IWF (US Large Cap Growth) and SPY (US Large Cap Blend) sit in different corners of the market, so this is less a head-to-head than a question of what role each would play. They can be complements rather than alternatives — the metrics below show how differently the two have actually behaved.
On ETFValuer's overall model — which blends return, risk-adjusted performance, cost, drawdown, size and volatility — SPY scores higher: 74.7 (Grade B) versus 59.2 for IWF. That doesn't make IWF a bad fund; it means SPY currently edges it out on this specific mix of factors. Read the metric-by-metric breakdown below before deciding which matters more for your own portfolio.
Head-to-Head: Every Metric
| IWF | SPY | |
|---|---|---|
| Category | US Large Cap Growth | US Large Cap Blend |
| Expense ratio | 0.18% | 0.09% |
| Fund size (AUM) | $128.9B | $781.2B |
| Dividend yield | 1.28% | 0.77% |
| 1-year return | +8.19% | +17.80% |
| 3-year return | +67.77% | +67.54% |
| Volatility | 17.10% | 12.68% |
| Max drawdown | -23.36% | -18.76% |
| Sharpe ratio | 0.19 | 1.01 |
| ETFValuer score | 59.2 | 74.7 |
| Grade | C | B |
| Overall rank | #257 | #53 |
Bold marks the better value in each row. "Better" is directional only (e.g. lower cost, higher return) — it isn't a recommendation by itself. See the full methodology.
Cost
SPY is the cheaper fund, charging 0.09% a year versus 0.18% for IWF — a gap of 0.09 percentage points (about $8.55/year on a $10,000 position) that compounds meaningfully over a multi-decade holding period. Because these funds do different jobs, though, cost alone shouldn't decide it — a cheaper fund that gives you the wrong exposure is a false economy. See the ETF Fee Calculator for the exact dollar impact at your investment size and horizon.
What IWF's Fees Cost You
IWF charges an expense ratio of 0.18% a year, deducted automatically from the fund's value. Small percentages compound into real money — adjust the figures below to see the impact on your own numbers.
Assumes a constant gross return and no additional contributions — a simplification, but it isolates exactly what the expense ratio costs. Try the full fee calculator to model contributions and compare any two funds.
Performance & Risk
Over the trailing 3 years, IWF returned +67.77% versus +67.54% for SPY — a gap of about 0.2 percentage points. On risk, SPY has held up better historically, with a shallower max drawdown (-18.76% vs. -23.36%). SPY currently has the better risk-adjusted return (Sharpe ratio of 1.01 vs. 0.19), meaning it delivered more return per unit of volatility taken on.
How Closely Do They Track Each Other?
Over the last 3.0 years of daily returns (752 shared trading days), IWF and SPY show a high correlation of 0.955 — closely related, but not identical. Holding both would add very little diversification: when one falls, the other almost always falls with it. Treat these as alternatives to each other, not as complements in the same portfolio.
| Measure | Value | What it means |
|---|---|---|
| Daily return correlation | 0.955 | High — closely related, but not identical |
| R-squared | 91.1% | 91.1% of IWF's daily moves are explained by SPY's |
| Tracking error (annualised) | 6.70% | Typical yearly spread between the two funds' returns |
| Annualised return over 3.0y | IWF +19.32% · SPY +19.12% | IWF ahead by 0.20 points a year |
Correlation alone understates how far these can drift. Across every rolling 12-month window in the period, IWF finished as much as +11.5 points ahead of SPY at the best extreme and -9.7 points at the worst — a 21.1-point spread between the best and worst year of relative performance. Two funds can correlate tightly day to day and still deliver very different outcomes over any single year you happen to hold them.
Calculated from daily total returns over the trailing 3-year window, recomputed every day this site refreshes. Correlation of 1.00 means the two funds moved in lockstep; 0.00 means their daily moves were unrelated.
Which One Should You Pick?
Lean IWF if…
- Current income matters to you — it yields 1.28% against 0.77%
Lean SPY if…
- You want the lower running cost — 0.09% vs 0.18%, about $9 a year less on a $10,000 position
- It has been the calmer ride (12.7% volatility vs 17.1%) with a shallower worst-case fall (-18.8% vs -23.4%)
- You care about return per unit of risk — its Sharpe ratio of 1.01 beats 0.19
- You want the deeper, more liquid market ($781B in assets vs $129B)
These two are not really substitutes, so "both, in some proportion" is often the right answer rather than picking one. Model the blend with the Portfolio Blender.
Frequently Asked Questions
Is IWF or SPY better?
On ETFValuer's overall model — which blends return, risk-adjusted performance, cost, drawdown, size and volatility — SPY scores higher: 74.7 (Grade B) versus 59.2 for IWF. That doesn't make IWF a bad fund; it means SPY currently edges it out on this specific mix of factors. Read the metric-by-metric breakdown below before deciding which matters more for your own portfolio.
Which has the lower expense ratio, IWF or SPY?
SPY currently has the lower expense ratio (0.09% vs. 0.18%).
Can I hold both IWF and SPY?
You can, though the benefit is limited. At a correlation of 0.95, IWF and SPY fall together far more often than not, so owning both adds complexity and a second expense ratio without much real diversification. Most investors are better served picking one.
Go deeper on either fund
Full daily-updated metrics, holdings context, and category peers.