SPMB vs. GNMA
SPMB (SPDR Portfolio Mortgage Backed Bond ETF) and GNMA (iShares GNMA Bond ETF) are both Mortgage Backed Securities funds - SPMB tracks the Bloomberg US Aggregate Securitized - MBS while GNMA tracks the Barclays Capital GNMA Index. Both are passively managed. Over the past 10 years, SPMB returned 1.28%/yr vs 1.20%/yr for GNMA. A 0.61 correlation means they provide meaningful diversification when combined. SPMB charges 0.04%/yr vs 0.15%/yr for GNMA.
Performance
SPMB vs. GNMA - Performance Comparison
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Returns By Period
The year-to-date returns for both stocks are quite close, with SPMB having a 0.76% return and GNMA slightly lower at 0.73%. Over the past 10 years, SPMB has outperformed GNMA with an annualized return of 1.28%, while GNMA has yielded a comparatively lower 1.20% annualized return.
SPMB
- 1D
- -0.25%
- 1M
- 0.65%
- YTD
- 0.76%
- 6M
- 0.83%
- 1Y
- 5.97%
- 3Y*
- 4.27%
- 5Y*
- 0.40%
- 10Y*
- 1.28%
GNMA
- 1D
- -0.14%
- 1M
- 0.81%
- YTD
- 0.73%
- 6M
- 1.01%
- 1Y
- 5.85%
- 3Y*
- 4.20%
- 5Y*
- 0.60%
- 10Y*
- 1.20%
SPMB vs. GNMA - Yearly Performance Comparison
| 2026 (YTD) | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | |
|---|---|---|---|---|---|---|---|---|---|---|
SPMB SPDR Portfolio Mortgage Backed Bond ETF | 0.76% | 8.29% | 1.35% | 5.09% | -12.05% | -1.46% | 4.19% | 6.16% | 1.01% | 2.13% |
GNMA iShares GNMA Bond ETF | 0.73% | 8.25% | 1.07% | 5.34% | -10.83% | -1.86% | 3.51% | 5.85% | 0.85% | 1.74% |
Correlation
The correlation between SPMB 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 | 0.90 |
Correlation (5Y) Calculated over the trailing 5-year period | 0.91 |
Correlation (10Y) Calculated over the trailing 10-year period | 0.75 |
Correlation (All Time) Calculated using the full available price history since Feb 21, 2012 | 0.61 |
Over the past year, SPMB and GNMA have become more correlated (0.82) than their long-term average of 0.61, meaning their price movements have been converging.
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Return for Risk
SPMB vs. GNMA — Risk / Return Rank
SPMB
GNMA
SPMB vs. GNMA - Risk-Adjusted Trends Comparison
This table presents a comparison of risk-adjusted performance metrics for SPDR Portfolio Mortgage Backed Bond ETF (SPMB) 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.
| SPMB | GNMA | Difference | |
|---|---|---|---|
| Sharpe ratioReturn per unit of total volatility | +0.04 | ||
| Sortino ratioReturn per unit of downside risk | +0.04 | ||
| Omega ratioGain probability vs. loss probability | 1.26 | 1.24 | +0.01 |
| Calmar ratioReturn relative to maximum drawdown | 2.08 | 2.25 | -0.17 |
| Martin ratioReturn relative to average drawdown | 6.45 | 6.76 | -0.31 |
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Drawdowns
SPMB vs. GNMA - Drawdown Comparison
The maximum SPMB drawdown since its inception was -18.03%, which is greater than GNMA's maximum drawdown of -17.09%. Use the drawdown chart below to compare losses from any high point for SPMB and GNMA.
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Drawdown Indicators
| SPMB | GNMA | Difference | |
|---|---|---|---|
Max DrawdownLargest peak-to-trough decline | -18.03% | -17.09% | -0.94% |
Max Drawdown (1Y)Largest decline over 1 year | -2.89% | -2.61% | -0.28% |
Max Drawdown (3Y)Largest decline over 3 years | -7.66% | -7.13% | -0.53% |
Max Drawdown (5Y)Largest decline over 5 years | -17.49% | -15.83% | -1.66% |
Max Drawdown (10Y)Largest decline over 10 years | -18.03% | -17.09% | -0.94% |
Current DrawdownCurrent decline from peak | -1.34% | -1.24% | -0.10% |
Average DrawdownAverage peak-to-trough decline | -2.85% | -3.65% | +0.80% |
Ulcer IndexDepth and duration of drawdowns from previous peaks | 0.93% | 0.87% | +0.06% |
Volatility
SPMB vs. GNMA - Volatility Comparison
The current volatility for SPDR Portfolio Mortgage Backed Bond ETF (SPMB) is 1.23%, while iShares GNMA Bond ETF (GNMA) has a volatility of 1.37%. This indicates that SPMB experiences smaller price fluctuations and is considered to be less risky than GNMA based on this measure. The chart below showcases a comparison of their rolling one-month volatility.
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Volatility by Period
| SPMB | GNMA | Difference | |
|---|---|---|---|
Volatility (1M)Calculated over the trailing 1-month period | 1.23% | 1.37% | -0.14% |
Volatility (6M)Calculated over the trailing 6-month period | 3.19% | 3.29% | -0.10% |
Volatility (1Y)Calculated over the trailing 1-year period | 4.23% | 4.26% | -0.03% |
Volatility (5Y)Calculated over the trailing 5-year period, annualized | 6.79% | 6.63% | +0.16% |
Volatility (10Y)Calculated over the trailing 10-year period, annualized | 7.61% | 5.14% | +2.47% |
SPMB vs. GNMA - Expense Ratio Comparison
SPMB has a 0.04% 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
SPMB vs. GNMA - Dividend Comparison
SPMB's dividend yield for the trailing twelve months is around 4.08%, less than GNMA's 4.23% 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% |
SPMB SPDR Portfolio Mortgage Backed Bond ETF | 4.08% | 3.98% | 3.76% | 3.21% | 2.98% | 2.59% | 2.95% | 3.24% | 3.36% | 3.13% | 2.99% | 3.05% |
Frequently Asked Questions
SPMB 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 (1.37%) compared to SPMB (1.23%). In terms of maximum drawdown, SPMB dropped -18.03% vs GNMA's -17.09%.
On 10-year performance, SPMB leads with 1.28% vs 1.20% for GNMA. On fees, SPMB is cheaper at 0.04% per year. On volatility, SPMB has been the lower-risk option at 1.23%. The better choice depends on whether you care most about return, fees, risk, or income.
Over the 10-year period, SPMB has performed better with a 1.28% return vs 1.20%. Past performance does not guarantee future results, so compare this with risk, fees, and fund exposure.
SPMB is cheaper with a 0.04% expense ratio, compared with 0.15% for GNMA.
GNMA has the higher dividend yield at 4.23%, compared with 4.08% for SPMB.
SPMB tracks Bloomberg US Aggregate Securitized - MBS, while GNMA tracks Barclays Capital GNMA Index. They also come from different issuers: State Street and iShares. Their fees differ too: 0.04% for SPMB and 0.15% for GNMA.
SPMB currently has the higher Sharpe Ratio (1.42 vs 1.38), 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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