GNMA vs. MBB
GNMA (iShares GNMA Bond ETF) and MBB (iShares MBS Bond ETF) are both Mortgage Backed Securities funds from iShares - GNMA tracks the Barclays Capital GNMA Index while MBB tracks the Barclays Capital U.S. MBS Index. Both are passively managed. Over the past 10 years, GNMA returned 1.23%/yr vs 1.31%/yr for MBB. A 0.69 correlation means they provide meaningful diversification when combined. GNMA charges 0.15%/yr vs 0.06%/yr for MBB.
Performance
GNMA vs. MBB - Performance Comparison
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Returns By Period
The year-to-date returns for both investments are quite close, with GNMA having a 0.67% return and MBB slightly higher at 0.68%. Over the past 10 years, GNMA has underperformed MBB with an annualized return of 1.23%, while MBB has yielded a comparatively higher 1.31% annualized return.
GNMA
- 1D
- 0.11%
- 1M
- 0.08%
- YTD
- 0.67%
- 6M
- 1.08%
- 1Y
- 5.88%
- 3Y*
- 4.33%
- 5Y*
- 0.55%
- 10Y*
- 1.23%
MBB
- 1D
- 0.11%
- 1M
- 0.25%
- YTD
- 0.68%
- 6M
- 1.10%
- 1Y
- 6.17%
- 3Y*
- 4.42%
- 5Y*
- 0.36%
- 10Y*
- 1.31%
GNMA vs. MBB - Yearly Performance Comparison
| 2026 (YTD) | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | |
|---|---|---|---|---|---|---|---|---|---|---|
GNMA iShares GNMA Bond ETF | 0.67% | 8.25% | 1.07% | 5.34% | -10.83% | -1.86% | 3.51% | 5.85% | 0.85% | 1.74% |
MBB iShares MBS Bond ETF | 0.68% | 8.38% | 1.31% | 5.01% | -11.74% | -1.43% | 4.08% | 6.18% | 0.82% | 2.49% |
Correlation
The correlation between GNMA and MBB 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 | 0.92 |
Correlation (10Y) Calculated over the trailing 10-year period | 0.81 |
Correlation (All Time) Calculated using the full available price history since Feb 22, 2012 | 0.69 |
The correlation between GNMA and MBB shifts across timeframes, from 0.69 (all time) to 0.92 (5 years), reflecting how their relationship changes across market environments.
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Return for Risk
GNMA vs. MBB — Risk / Return Rank
GNMA
MBB
GNMA vs. MBB - Risk-Adjusted Trends Comparison
This table presents a comparison of risk-adjusted performance metrics for iShares GNMA Bond ETF (GNMA) and iShares MBS Bond ETF (MBB). 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.
| GNMA | MBB | Difference | |
|---|---|---|---|
| Sharpe ratioReturn per unit of total volatility | +0.01 | ||
| Sortino ratioReturn per unit of downside risk | +0.08 | ||
| Omega ratioGain probability vs. loss probability | 1.25 | 1.25 | 0.00 |
| Calmar ratioReturn relative to maximum drawdown | 2.26 | 2.10 | +0.16 |
| Martin ratioReturn relative to average drawdown | 7.20 | 6.96 | +0.24 |
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
| GNMA | MBB | Difference | |
|---|---|---|---|
Sharpe Ratio (1Y)Calculated over the trailing 1-year period | 1.40 | 1.39 | +0.01 |
Sharpe Ratio (5Y)Calculated over the trailing 5-year period | 0.08 | 0.05 | +0.03 |
Sharpe Ratio (10Y)Calculated over the trailing 10-year period | 0.24 | 0.25 | -0.01 |
Sharpe Ratio (All Time)Calculated using the full available price history | 0.25 | 0.59 | -0.34 |
Drawdowns
GNMA vs. MBB - Drawdown Comparison
The maximum GNMA drawdown since its inception was -17.09%, roughly equal to the maximum MBB drawdown of -17.64%. Use the drawdown chart below to compare losses from any high point for GNMA and MBB.
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Drawdown Indicators
| GNMA | MBB | Difference | |
|---|---|---|---|
Max DrawdownLargest peak-to-trough decline | -17.09% | -17.64% | +0.55% |
Max Drawdown (1Y)Largest decline over 1 year | -2.61% | -2.94% | +0.33% |
Max Drawdown (3Y)Largest decline over 3 years | -7.13% | -7.68% | +0.55% |
Max Drawdown (5Y)Largest decline over 5 years | -15.83% | -17.19% | +1.36% |
Max Drawdown (10Y)Largest decline over 10 years | -17.09% | -17.64% | +0.55% |
Current DrawdownCurrent decline from peak | -1.30% | -1.42% | +0.12% |
Average DrawdownAverage peak-to-trough decline | -3.66% | -2.35% | -1.31% |
Ulcer IndexDepth and duration of drawdowns from previous peaks | 0.82% | 0.89% | -0.07% |
Volatility
GNMA vs. MBB - Volatility Comparison
iShares GNMA Bond ETF (GNMA) and iShares MBS Bond ETF (MBB) have volatilities of 1.54% and 1.58%, 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
| GNMA | MBB | Difference | |
|---|---|---|---|
Volatility (1M)Calculated over the trailing 1-month period | 1.54% | 1.58% | -0.04% |
Volatility (6M)Calculated over the trailing 6-month period | 3.14% | 3.23% | -0.09% |
Volatility (1Y)Calculated over the trailing 1-year period | 4.29% | 4.51% | -0.22% |
Volatility (5Y)Calculated over the trailing 5-year period, annualized | 6.61% | 6.81% | -0.20% |
Volatility (10Y)Calculated over the trailing 10-year period, annualized | 5.13% | 5.31% | -0.18% |
GNMA vs. MBB - Expense Ratio Comparison
GNMA has a 0.15% expense ratio, which is higher than MBB's 0.06% 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
GNMA vs. MBB - Dividend Comparison
GNMA's dividend yield for the trailing twelve months is around 4.23%, which matches MBB's 4.27% yield.
| Position | TTM | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
GNMA iShares GNMA Bond ETF | 4.23% | 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 | 4.27% | 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
GNMA and MBB 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.
MBB has higher volatility (1.58%) compared to GNMA (1.54%). In terms of maximum drawdown, GNMA dropped -17.09% vs MBB's -17.64%.
On 10-year performance, MBB leads with 1.31% vs 1.23% 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 1.31% return vs 1.23%. 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 4.27%, compared with 4.23% for GNMA.
GNMA tracks Barclays Capital GNMA Index, while MBB tracks Barclays Capital U.S. MBS Index. Their fees differ too: 0.15% for GNMA and 0.06% for MBB.
GNMA currently has the higher Sharpe Ratio (1.40 vs 1.39), 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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