MBB vs. IWM
MBB (iShares MBS Bond ETF) and IWM (iShares Russell 2000 ETF) are both exchange-traded funds - MBB is a Mortgage Backed Securities fund tracking the Barclays Capital U.S. MBS Index, while IWM is a Small Cap Blend Equities fund tracking the Russell 2000 Index. Both are passively managed. Over the past 10 years, MBB returned 1.30%/yr vs 10.93%/yr for IWM. At a correlation of -0.07, they often move in opposite directions. MBB charges 0.06%/yr vs 0.19%/yr for IWM.
Performance
MBB vs. IWM - Performance Comparison
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Returns By Period
In the year-to-date period, MBB achieves a 0.58% return, which is significantly lower than IWM's 17.07% return. Over the past 10 years, MBB has underperformed IWM with an annualized return of 1.30%, while IWM has yielded a comparatively higher 10.93% annualized return.
MBB
- 1D
- -0.23%
- 1M
- 0.31%
- YTD
- 0.58%
- 6M
- 0.71%
- 1Y
- 6.76%
- 3Y*
- 4.36%
- 5Y*
- 0.34%
- 10Y*
- 1.30%
IWM
- 1D
- -1.37%
- 1M
- 3.52%
- YTD
- 17.07%
- 6M
- 15.83%
- 1Y
- 39.10%
- 3Y*
- 17.88%
- 5Y*
- 6.11%
- 10Y*
- 10.93%
MBB vs. IWM - Yearly Performance Comparison
| 2026 (YTD) | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | |
|---|---|---|---|---|---|---|---|---|---|---|
MBB iShares MBS Bond ETF | 0.58% | 8.38% | 1.31% | 5.01% | -11.74% | -1.43% | 4.08% | 6.18% | 0.82% | 2.49% |
IWM iShares Russell 2000 ETF | 17.07% | 12.66% | 11.38% | 16.83% | -20.48% | 14.54% | 20.03% | 25.39% | -11.12% | 14.58% |
Correlation
The correlation between MBB and IWM is 0.30, which is low. Their price movements are largely independent, making them effective diversification partners.
| Correlation | |
|---|---|
Correlation (1Y) Calculated over the trailing 1-year period | 0.30 |
Correlation (3Y) Calculated over the trailing 3-year period | 0.27 |
Correlation (5Y) Calculated over the trailing 5-year period | 0.21 |
Correlation (10Y) Calculated over the trailing 10-year period | 0.08 |
Correlation (All Time) Calculated using the full available price history since Mar 19, 2007 | -0.07 |
The correlation between MBB and IWM shifts across timeframes, from -0.07 (all time) to 0.30 (1 year), reflecting how their relationship changes across market environments.
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Return for Risk
MBB vs. IWM — Risk / Return Rank
MBB
IWM
MBB vs. IWM - Risk-Adjusted Trends Comparison
This table presents a comparison of risk-adjusted performance metrics for iShares MBS Bond ETF (MBB) and iShares Russell 2000 ETF (IWM). 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.
| MBB | IWM | Difference | |
|---|---|---|---|
| Sharpe ratioReturn per unit of total volatility | -0.55 | ||
| Sortino ratioReturn per unit of downside risk | -0.64 | ||
| Omega ratioGain probability vs. loss probability | 1.27 | 1.34 | -0.07 |
| Calmar ratioReturn relative to maximum drawdown | 2.31 | 3.56 | -1.26 |
| Martin ratioReturn relative to average drawdown | 7.64 | 12.64 | -5.00 |
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month. | |||
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Sharpe Ratios by Period
| MBB | IWM | Difference | |
|---|---|---|---|
Sharpe Ratio (1Y)Calculated over the trailing 1-year period | 1.51 | 2.05 | -0.55 |
Sharpe Ratio (5Y)Calculated over the trailing 5-year period | 0.05 | 0.27 | -0.22 |
Sharpe Ratio (10Y)Calculated over the trailing 10-year period | 0.25 | 0.48 | -0.23 |
Sharpe Ratio (All Time)Calculated using the full available price history | 0.58 | 0.37 | +0.22 |
Drawdowns
MBB vs. IWM - Drawdown Comparison
The maximum MBB drawdown since its inception was -17.64%, smaller than the maximum IWM drawdown of -59.05%. Use the drawdown chart below to compare losses from any high point for MBB and IWM.
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Drawdown Indicators
| MBB | IWM | Difference | |
|---|---|---|---|
Max DrawdownLargest peak-to-trough decline | -17.64% | -59.05% | +41.41% |
Max Drawdown (1Y)Largest decline over 1 year | -2.94% | -11.03% | +8.09% |
Max Drawdown (3Y)Largest decline over 3 years | -7.68% | -27.50% | +19.82% |
Max Drawdown (5Y)Largest decline over 5 years | -17.19% | -31.91% | +14.72% |
Max Drawdown (10Y)Largest decline over 10 years | -17.64% | -41.13% | +23.49% |
Current DrawdownCurrent decline from peak | -1.52% | -1.49% | -0.03% |
Average DrawdownAverage peak-to-trough decline | -2.35% | -10.77% | +8.42% |
Ulcer IndexDepth and duration of drawdowns from previous peaks | 0.89% | 3.10% | -2.21% |
Volatility
MBB vs. IWM - Volatility Comparison
The current volatility for iShares MBS Bond ETF (MBB) is 1.59%, while iShares Russell 2000 ETF (IWM) has a volatility of 5.75%. This indicates that MBB experiences smaller price fluctuations and is considered to be less risky than IWM based on this measure. The chart below showcases a comparison of their rolling one-month volatility.
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Volatility by Period
| MBB | IWM | Difference | |
|---|---|---|---|
Volatility (1M)Calculated over the trailing 1-month period | 1.59% | 5.75% | -4.16% |
Volatility (6M)Calculated over the trailing 6-month period | 3.23% | 13.53% | -10.30% |
Volatility (1Y)Calculated over the trailing 1-year period | 4.51% | 19.20% | -14.69% |
Volatility (5Y)Calculated over the trailing 5-year period, annualized | 6.81% | 22.52% | -15.71% |
Volatility (10Y)Calculated over the trailing 10-year period, annualized | 5.31% | 23.04% | -17.73% |
MBB vs. IWM - Expense Ratio Comparison
MBB has a 0.06% expense ratio, which is lower than IWM's 0.19% expense ratio. Despite the difference, both funds are considered low-cost compared to the broader market, where average expense ratios usually range from 0.3% to 0.9%.
Dividends
MBB vs. IWM - Dividend Comparison
MBB's dividend yield for the trailing twelve months is around 4.28%, more than IWM's 0.88% yield.
| Position | TTM | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
IWM iShares Russell 2000 ETF | 0.88% | 1.04% | 1.15% | 1.35% | 1.48% | 0.94% | 1.04% | 1.26% | 1.40% | 1.26% | 1.38% | 1.54% |
MBB iShares MBS Bond ETF | 4.28% | 4.21% | 3.94% | 3.40% | 2.31% | 1.05% | 2.10% | 2.77% | 2.64% | 2.23% | 2.58% | 2.66% |
Frequently Asked Questions
MBB and IWM have a correlation of 0.30, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.
IWM has higher volatility (5.75%) compared to MBB (1.59%). In terms of maximum drawdown, MBB dropped -17.64% vs IWM's -59.05%.
On 10-year performance, IWM leads with 10.93% vs 1.30% for MBB. On fees, MBB is cheaper at 0.06% per year. On volatility, MBB has been the lower-risk option at 1.59%. The better choice depends on whether you care most about return, fees, risk, or income.
Over the 10-year period, IWM has performed better with a 10.93% return vs 1.30%. Past performance does not guarantee future results, so compare this with risk, fees, and fund exposure.
MBB is cheaper with a 0.06% expense ratio, compared with 0.19% for IWM.
MBB has the higher dividend yield at 4.28%, compared with 0.88% for IWM.
MBB is categorized as Mortgage Backed Securities, while IWM is Small Cap Blend Equities. MBB tracks Barclays Capital U.S. MBS Index, while IWM tracks Russell 2000 Index. Their fees differ too: 0.06% for MBB and 0.19% for IWM.
IWM currently has the higher Sharpe Ratio (2.05 vs 1.51), 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.
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