SPMB vs. MBB
SPMB (SPDR Portfolio Mortgage Backed Bond ETF) and MBB (iShares MBS Bond ETF) are both Mortgage Backed Securities funds - SPMB tracks the Bloomberg US Aggregate Securitized - MBS while MBB tracks the Barclays Capital U.S. MBS Index. Both are passively managed. Over the past 10 years, SPMB returned 1.34%/yr vs 1.34%/yr for MBB. A 0.71 correlation means they provide meaningful diversification when combined. SPMB charges 0.04%/yr vs 0.06%/yr for MBB.
Performance
SPMB vs. MBB - Performance Comparison
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Returns By Period
In the year-to-date period, SPMB achieves a 1.33% return, which is significantly higher than MBB's 1.26% return. Over a longer period, both investments have demonstrated similar performance, with their 10-year annualized returns being quite close: SPMB at 1.34% and MBB at 1.34%.
SPMB
- 1D
- 0.45%
- 1M
- 1.22%
- YTD
- 1.33%
- 6M
- 1.17%
- 1Y
- 6.08%
- 3Y*
- 4.46%
- 5Y*
- 0.51%
- 10Y*
- 1.34%
MBB
- 1D
- 0.43%
- 1M
- 1.07%
- YTD
- 1.26%
- 6M
- 1.05%
- 1Y
- 5.71%
- 3Y*
- 4.50%
- 5Y*
- 0.54%
- 10Y*
- 1.34%
SPMB vs. MBB - Yearly Performance Comparison
| 2026 (YTD) | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | |
|---|---|---|---|---|---|---|---|---|---|---|
SPMB SPDR Portfolio Mortgage Backed Bond ETF | 1.33% | 8.29% | 1.35% | 5.09% | -12.05% | -1.46% | 4.19% | 6.16% | 1.01% | 2.13% |
MBB iShares MBS Bond ETF | 1.26% | 8.38% | 1.31% | 5.01% | -11.74% | -1.43% | 4.08% | 6.18% | 0.82% | 2.49% |
Correlation
The correlation between SPMB and MBB is 0.96 - these two move nearly in lockstep. At this level, holding both provides almost no diversification benefit. If you already own one, adding the other does little to reduce portfolio risk.
| Correlation | |
|---|---|
Correlation (1Y) Calculated over the trailing 1-year period | 0.96 |
Correlation (3Y) Calculated over the trailing 3-year period | 0.97 |
Correlation (5Y) Calculated over the trailing 5-year period | 0.97 |
Correlation (10Y) Calculated over the trailing 10-year period | 0.86 |
Correlation (All Time) Calculated using the full available price history since Jan 30, 2009 | 0.71 |
Over the past year, SPMB and MBB have become more correlated (0.96) than their long-term average of 0.71, meaning their price movements have been converging.
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Return for Risk
SPMB vs. MBB — Risk / Return Rank
SPMB
MBB
SPMB vs. MBB - Risk-Adjusted Trends Comparison
This table presents a comparison of risk-adjusted performance metrics for SPDR Portfolio Mortgage Backed Bond ETF (SPMB) 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.
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 | MBB | Difference | |
|---|---|---|---|
| Sharpe ratioReturn per unit of total volatility | +0.15 | ||
| Sortino ratioReturn per unit of downside risk | +0.28 | ||
| Omega ratioGain probability vs. loss probability | 1.26 | 1.23 | +0.03 |
| Calmar ratioReturn relative to maximum drawdown | 2.11 | 1.95 | +0.17 |
| Martin ratioReturn relative to average drawdown | 6.54 | 6.07 | +0.47 |
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Drawdowns
SPMB vs. MBB - Drawdown Comparison
The maximum SPMB drawdown since its inception was -18.03%, roughly equal to the maximum MBB drawdown of -17.64%. Use the drawdown chart below to compare losses from any high point for SPMB and MBB.
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Drawdown Indicators
| SPMB | MBB | Difference | |
|---|---|---|---|
Max DrawdownLargest peak-to-trough decline | -18.03% | -17.64% | -0.39% |
Max Drawdown (1Y)Largest decline over 1 year | -2.89% | -2.94% | +0.05% |
Max Drawdown (3Y)Largest decline over 3 years | -7.66% | -7.68% | +0.02% |
Max Drawdown (5Y)Largest decline over 5 years | -17.49% | -17.19% | -0.30% |
Max Drawdown (10Y)Largest decline over 10 years | -18.03% | -17.64% | -0.39% |
Current DrawdownCurrent decline from peak | -0.79% | -0.85% | +0.06% |
Average DrawdownAverage peak-to-trough decline | -2.85% | -2.34% | -0.51% |
Ulcer IndexDepth and duration of drawdowns from previous peaks | 0.93% | 0.94% | -0.01% |
Volatility
SPMB vs. MBB - Volatility Comparison
SPDR Portfolio Mortgage Backed Bond ETF (SPMB) and iShares MBS Bond ETF (MBB) have volatilities of 1.28% and 1.32%, 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
| SPMB | MBB | Difference | |
|---|---|---|---|
Volatility (1M)Calculated over the trailing 1-month period | 1.28% | 1.32% | -0.04% |
Volatility (6M)Calculated over the trailing 6-month period | 3.20% | 3.34% | -0.14% |
Volatility (1Y)Calculated over the trailing 1-year period | 4.25% | 4.47% | -0.22% |
Volatility (5Y)Calculated over the trailing 5-year period, annualized | 6.79% | 6.83% | -0.04% |
Volatility (10Y)Calculated over the trailing 10-year period, annualized | 7.61% | 5.32% | +2.29% |
SPMB vs. MBB - Expense Ratio Comparison
SPMB has a 0.04% expense ratio, which is lower than MBB's 0.06% 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. MBB - Dividend Comparison
SPMB's dividend yield for the trailing twelve months is around 4.06%, less than MBB's 4.25% yield.
| Position | TTM | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
MBB iShares MBS Bond ETF | 4.25% | 4.21% | 3.94% | 3.40% | 2.31% | 1.05% | 2.10% | 2.77% | 2.64% | 2.23% | 2.58% | 2.66% |
SPMB SPDR Portfolio Mortgage Backed Bond ETF | 4.06% | 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
With a correlation of 0.96, SPMB and MBB move almost identically. Holding both adds very little diversification - you're essentially doubling your position in the same market segment. Choosing one is usually more capital-efficient.
MBB has higher volatility (1.32%) compared to SPMB (1.28%). In terms of maximum drawdown, SPMB dropped -18.03% vs MBB's -17.64%.
On 10-year performance, MBB leads with 1.34% vs 1.34% for SPMB. On fees, SPMB is cheaper at 0.04% 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 1.34% return vs 1.34%. 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 0.06% for MBB.
MBB has the higher dividend yield at 4.25%, compared with 4.06% for SPMB.
SPMB tracks Bloomberg US Aggregate Securitized - MBS, while MBB tracks Barclays Capital U.S. MBS Index. They also come from different issuers: State Street and iShares. Their fees differ too: 0.04% for SPMB and 0.06% for MBB.
SPMB currently has the higher Sharpe Ratio (1.44 vs 1.29), 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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