IWO vs. MDY

Last updated Jun 4, 2026

IWO (iShares Russell 2000 Growth ETF) and MDY (SPDR S&P MidCap 400 ETF) are both Small Cap Growth Equities funds - IWO tracks the Russell 2000 Growth Index while MDY tracks the S&P MidCap 400 Index. Both are passively managed. Over the past 10 years, IWO returned 11.23%/yr vs 11.04%/yr for MDY. Their correlation of 0.92 suggests significant overlap in exposure. IWO charges 0.24%/yr vs 0.23%/yr for MDY.

Performance

IWO vs. MDY - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in iShares Russell 2000 Growth ETF (IWO) and SPDR S&P MidCap 400 ETF (MDY). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, IWO achieves a 16.75% return, which is significantly higher than MDY's 13.91% return. Both investments have delivered pretty close results over the past 10 years, with IWO having a 11.23% annualized return and MDY not far behind at 11.04%.

IWO

• 1D: -1.41%
• 1M: 4.28%
• YTD: 16.75%
• 6M: 15.06%
• 1Y: 37.09%
• 3Y*: 18.01%
• 5Y*: 5.56%
• 10Y*: 11.23%

MDY

• 1D: -0.09%
• 1M: 3.81%
• YTD: 13.91%
• 6M: 14.15%
• 1Y: 25.00%
• 3Y*: 15.77%
• 5Y*: 7.92%
• 10Y*: 11.04%

*Multi-year figures are annualized to reflect compound growth (CAGR)

IWO vs. MDY - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
IWO iShares Russell 2000 Growth ETF	16.75%	12.90%	15.04%	18.51%	-26.27%	2.54%	34.68%	28.48%	-9.43%	22.25%
MDY SPDR S&P MidCap 400 ETF	13.91%	7.19%	13.64%	16.07%	-13.28%	24.53%	13.50%	25.78%	-11.29%	15.93%

Correlation

The correlation between IWO and MDY is 0.87, indicating a strong positive relationship between their price movements. Combining them offers limited diversification - they tend to fall together during downturns.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.87
Correlation (3Y) Calculated over the trailing 3-year period	0.91
Correlation (5Y) Calculated over the trailing 5-year period	0.92
Correlation (10Y) Calculated over the trailing 10-year period	0.91
Correlation (All Time) Calculated using the full available price history since Jul 31, 2000	0.92

The correlation between IWO and MDY has been stable across timeframes, ranging from 0.87 to 0.92 - a consistent structural relationship.

IWO vs. MDY - Sectors Allocation Comparison

Sectors	IWO	MDY
Technology	23.6%	15.4%
Industrials	23.1%	25.1%
Healthcare	22.4%	8.7%
Financial Services	8.2%	13.9%
Consumer Cyclical	7.7%	10.8%
Basic Materials	4.2%	4.8%
Energy	3.5%	5.6%
Consumer Defensive	2.6%	3.8%
Communication Services	2.2%	1.0%
Real Estate	2.1%	7.7%
Utilities	0.7%	3.1%

Return for Risk

IWO vs. MDY — Risk / Return Rank

Compare risk-adjusted metric ranks to identify better-performing investments over the past 12 months.

IWO

IWO Risk / Return Rank: 49
IWO Sharpe Ratio Rank: 50
IWO Sortino Ratio Rank: 49
IWO Omega Ratio Rank: 45
IWO Calmar Ratio Rank: 50
IWO Martin Ratio Rank: 52

MDY

MDY Risk / Return Rank: 50
MDY Sharpe Ratio Rank: 46
MDY Sortino Ratio Rank: 46
MDY Omega Ratio Rank: 44
MDY Calmar Ratio Rank: 56
MDY Martin Ratio Rank: 58

The rank (0–100) shows how this investment's returns compare to the risk taken. Higher = better. Based on the past 12 months of data, combining Sharpe, Sortino, and other metrics used by quantitative funds and institutional investors.

IWO vs. MDY - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for iShares Russell 2000 Growth ETF (IWO) and SPDR S&P MidCap 400 ETF (MDY). Risk-adjusted metrics are performance indicators that assess an investment's returns in relation to its risk, enabling a more accurate comparison of different investment options.

	IWO	MDY	Difference
Sharpe ratio: Return per unit of total volatility	1.75	1.63	+0.12
Sortino ratio: Return per unit of downside risk	2.42	2.39	+0.04
Omega ratio: Gain probability vs. loss probability	1.29	1.29	0.00
Calmar ratio: Return relative to maximum drawdown	2.51	2.85	-0.34
Martin ratio: Return relative to average drawdown	8.99	10.38	-1.39
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

IWO vs. MDY - Sharpe Ratio Comparison

The current IWO Sharpe Ratio is 1.75, which is comparable to the MDY Sharpe Ratio of 1.63. The chart below compares the historical Sharpe Ratios of IWO and MDY, calculated using daily returns over the previous 12 months. A higher Sharpe Ratio indicates better risk-adjusted performance relative to the risk-free rate.

Sharpe Ratios by Period

	IWO	MDY	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.75	1.63	+0.12
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.23	0.40	-0.17
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.47	0.52	-0.06
Sharpe Ratio (All Time) Calculated using the full available price history	0.28	0.53	-0.24

Drawdowns

IWO vs. MDY - Drawdown Comparison

The maximum IWO drawdown since its inception was -60.11%, which is greater than MDY's maximum drawdown of -55.33%. Use the drawdown chart below to compare losses from any high point for IWO and MDY.

Drawdown Indicators

	IWO	MDY	Difference
Max Drawdown Largest peak-to-trough decline	-60.11%	-55.33%	-4.78%
Max Drawdown (1Y) Largest decline over 1 year	-14.87%	-8.82%	-6.05%
Max Drawdown (3Y) Largest decline over 3 years	-28.57%	-24.03%	-4.54%
Max Drawdown (5Y) Largest decline over 5 years	-40.51%	-24.03%	-16.48%
Max Drawdown (10Y) Largest decline over 10 years	-42.02%	-42.22%	+0.20%
Current Drawdown Current decline from peak	-1.51%	-0.09%	-1.42%
Average Drawdown Average peak-to-trough decline	-16.71%	-7.03%	-9.68%
Ulcer Index Depth and duration of drawdowns from previous peaks	4.14%	2.42%	+1.72%

Volatility

IWO vs. MDY - Volatility Comparison

iShares Russell 2000 Growth ETF (IWO) has a higher volatility of 6.61% compared to SPDR S&P MidCap 400 ETF (MDY) at 4.33%. This indicates that IWO's price experiences larger fluctuations and is considered to be riskier than MDY based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	IWO	MDY	Difference
Volatility (1M) Calculated over the trailing 1-month period	6.61%	4.33%	+2.28%
Volatility (6M) Calculated over the trailing 6-month period	15.65%	11.28%	+4.37%
Volatility (1Y) Calculated over the trailing 1-year period	21.34%	15.48%	+5.86%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	24.48%	19.77%	+4.71%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	24.13%	21.19%	+2.94%

IWO vs. MDY - Expense Ratio Comparison

IWO has a 0.24% expense ratio, which is higher than MDY's 0.23% expense ratio. However, both funds are considered low-cost compared to the broader market, where average expense ratios usually range from 0.3% to 0.9%.

Dividends

IWO vs. MDY - Dividend Comparison

IWO's dividend yield for the trailing twelve months is around 0.40%, less than MDY's 1.04% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
IWO iShares Russell 2000 Growth ETF	0.40%	0.56%	0.80%	0.73%	0.73%	0.32%	0.44%	0.71%	0.76%	0.73%	0.97%	0.89%
MDY SPDR S&P MidCap 400 ETF	1.04%	1.15%	1.18%	1.21%	1.37%	0.96%	1.12%	1.34%	1.39%	1.18%	1.31%	1.35%

Frequently Asked Questions

Can I hold both IWO and MDY in my portfolio?

IWO and MDY have a correlation of 0.87, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, IWO or MDY?

IWO has higher volatility (6.61%) compared to MDY (4.33%). In terms of maximum drawdown, IWO dropped -60.11% vs MDY's -55.33%.

Which ETF is better, IWO or MDY?

On 10-year performance, IWO leads with 11.23% vs 11.04% for MDY. On fees, MDY is cheaper at 0.23% per year. On volatility, MDY has been the lower-risk option at 4.33%. The better choice depends on whether you care most about return, fees, risk, or income.

Which ETF has performed better, IWO or MDY?

Over the 10-year period, IWO has performed better with a 11.23% return vs 11.04%. Past performance does not guarantee future results, so compare this with risk, fees, and fund exposure.

Which ETF is cheaper, IWO or MDY?

MDY is cheaper with a 0.23% expense ratio, compared with 0.24% for IWO.

Which ETF pays a higher dividend yield, IWO or MDY?

MDY has the higher dividend yield at 1.04%, compared with 0.40% for IWO.

What is the main difference between IWO and MDY?

IWO tracks Russell 2000 Growth Index, while MDY tracks S&P MidCap 400 Index. They also come from different issuers: iShares and State Street. Their fees differ too: 0.24% for IWO and 0.23% for MDY.

Which has better risk-adjusted returns?

IWO currently has the higher Sharpe Ratio (1.75 vs 1.63), meaning it's delivered slightly more return per unit of risk over the trailing 12 months. However, this ranking shifts over time - use the Risk/Return Score above for a more comprehensive view that combines Sharpe, Sortino, and other measures used by quantitative funds.