MBB vs. GNMA
MBB (iShares MBS Bond ETF) and GNMA (iShares GNMA Bond ETF) are both Mortgage Backed Securities funds from iShares - MBB tracks the Barclays Capital U.S. MBS Index while GNMA tracks the Barclays Capital GNMA Index. Both are passively managed. Over the past 10 years, MBB returned 1.19%/yr vs 1.12%/yr for GNMA. A 0.69 correlation means they provide meaningful diversification when combined. MBB charges 0.06%/yr vs 0.15%/yr for GNMA.
Performance
MBB vs. GNMA - Performance Comparison
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Returns By Period
In the year-to-date period, MBB achieves a 0.02% return, which is significantly lower than GNMA's 0.03% return. Over the past 10 years, MBB has outperformed GNMA with an annualized return of 1.19%, while GNMA has yielded a comparatively lower 1.12% annualized return.
MBB
- 1D
- -0.49%
- 1M
- -0.83%
- 6M
- -0.43%
- YTD
- 0.02%
- 1Y
- 4.79%
- 3Y*
- 4.12%
- 5Y*
- 0.21%
- 10Y*
- 1.19%
GNMA
- 1D
- -0.56%
- 1M
- -0.48%
- 6M
- -0.44%
- YTD
- 0.03%
- 1Y
- 4.96%
- 3Y*
- 4.06%
- 5Y*
- 0.43%
- 10Y*
- 1.12%
MBB vs. GNMA - Yearly Performance Comparison
| 2026 (YTD) | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | |
|---|---|---|---|---|---|---|---|---|---|---|
MBB iShares MBS Bond ETF | 0.02% | 8.38% | 1.31% | 5.01% | -11.74% | -1.43% | 4.08% | 6.18% | 0.82% | 2.49% |
GNMA iShares GNMA Bond ETF | 0.03% | 8.25% | 1.07% | 5.34% | -10.83% | -1.86% | 3.51% | 5.85% | 0.85% | 1.74% |
Correlation
The correlation between MBB and GNMA is 0.82, 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 | 0.82 |
Correlation (3Y) Calculated over the trailing 3-year period | 0.91 |
Correlation (5Y) Calculated over the trailing 5-year period | 0.93 |
Correlation (10Y) Calculated over the trailing 10-year period | 0.81 |
Correlation (All Time) Calculated using the full available price history since Feb 21, 2012 | 0.70 |
The correlation between MBB and GNMA shifts across timeframes, from 0.69 (all time) to 0.93 (5 years), reflecting how their relationship changes across market environments.
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Return for Risk
MBB vs. GNMA — Risk / Return Rank
MBB
GNMA
MBB vs. GNMA - Risk-Adjusted Trends Comparison
This table presents a comparison of risk-adjusted performance metrics for iShares MBS Bond ETF (MBB) and iShares GNMA Bond ETF (GNMA). 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.
Values are calculated on a 1-year rolling basis and updated daily. Risk-adjusted metrics are more stable over longer periods — use the period switch above to explore them.
| MBB | GNMA | Difference | |
|---|---|---|---|
| Sharpe ratioReturn per unit of total volatility | -0.09 | ||
| Sortino ratioReturn per unit of downside risk | -0.20 | ||
| Omega ratioGain probability vs. loss probability | 1.19 | 1.21 | -0.01 |
| Calmar ratioReturn relative to maximum drawdown | 1.63 | 1.91 | -0.27 |
| Martin ratioReturn relative to average drawdown | 4.97 | 5.65 | -0.69 |
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Drawdowns
MBB vs. GNMA - Drawdown Comparison
The maximum MBB drawdown since its inception was -17.64%, roughly equal to the maximum GNMA drawdown of -17.09%. Use the drawdown chart below to compare losses from any high point for MBB and GNMA.
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Drawdown Indicators
| MBB | GNMA | Difference | |
|---|---|---|---|
Max DrawdownLargest peak-to-trough decline | -17.64% | -17.09% | -0.55% |
Max Drawdown (1Y)Largest decline over 1 year | -2.94% | -2.61% | -0.33% |
Max Drawdown (3Y)Largest decline over 3 years | -7.59% | -7.00% | -0.59% |
Max Drawdown (5Y)Largest decline over 5 years | -17.19% | -15.83% | -1.36% |
Max Drawdown (10Y)Largest decline over 10 years | -17.64% | -17.09% | -0.55% |
Current DrawdownCurrent decline from peak | -2.06% | -1.92% | -0.14% |
Average DrawdownAverage peak-to-trough decline | -2.34% | -3.64% | +1.30% |
Ulcer IndexDepth and duration of drawdowns from previous peaks | 0.97% | 0.88% | +0.09% |
Volatility
MBB vs. GNMA - Volatility Comparison
iShares MBS Bond ETF (MBB) and iShares GNMA Bond ETF (GNMA) have volatilities of 1.44% and 1.46%, respectively, indicating that both stocks experience similar levels of price fluctuations. This suggests that the risk associated with both stocks, as measured by volatility, is nearly the same. The chart below showcases a comparison of their rolling one-month volatility.
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Volatility by Period
| MBB | GNMA | Difference | |
|---|---|---|---|
Volatility (1M)Calculated over the trailing 1-month period | 1.44% | 1.46% | -0.02% |
Volatility (6M)Calculated over the trailing 6-month period | 3.44% | 3.35% | +0.09% |
Volatility (1Y)Calculated over the trailing 1-year period | 4.43% | 4.24% | +0.19% |
Volatility (5Y)Calculated over the trailing 5-year period, annualized | 6.84% | 6.64% | +0.20% |
Volatility (10Y)Calculated over the trailing 10-year period, annualized | 5.33% | 5.14% | +0.19% |
MBB vs. GNMA - Expense Ratio Comparison
MBB has a 0.06% expense ratio, which is lower than GNMA's 0.15% 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. GNMA - Dividend Comparison
MBB's dividend yield for the trailing twelve months is around 4.32%, which matches GNMA's 4.28% yield.
| Position | TTM | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
GNMA iShares GNMA Bond ETF | 4.28% | 4.19% | 4.15% | 3.43% | 2.01% | 0.64% | 1.89% | 2.61% | 2.41% | 2.15% | 1.89% | 1.50% |
MBB iShares MBS Bond ETF | 4.32% | 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 GNMA have a correlation of 0.82, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.
GNMA has higher volatility (1.46%) compared to MBB (1.44%). In terms of maximum drawdown, MBB dropped -17.64% vs GNMA's -17.09%.
On 10-year performance, MBB leads with 1.19% vs 1.12% for GNMA. On fees, MBB is cheaper at 0.06% per year. Their volatility is very similar. The better choice depends on whether you care most about return, fees, risk, or income.
Over the 10-year period, MBB has performed better with a 1.19% return vs 1.12%. 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 0.15% for GNMA.
MBB has the higher dividend yield at 4.32%, compared with 4.28% for GNMA.
MBB tracks Barclays Capital U.S. MBS Index, while GNMA tracks Barclays Capital GNMA Index. Their fees differ too: 0.06% for MBB and 0.15% for GNMA.
GNMA currently has the higher Sharpe Ratio (1.18 vs 1.09), 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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