SPMB vs. IUSB
SPMB (SPDR Portfolio Mortgage Backed Bond ETF) and IUSB (iShares Core Universal USD Bond ETF) are both exchange-traded funds - SPMB is a Mortgage Backed Securities fund tracking the Bloomberg US Aggregate Securitized - MBS, while IUSB is a Intermediate Core-Plus Bond fund tracking the Bloomberg U.S. Universal Index. Both are passively managed. Over the past 10 years, SPMB returned 1.26%/yr vs 1.97%/yr for IUSB. A 0.73 correlation means they provide meaningful diversification when combined. SPMB charges 0.04%/yr vs 0.06%/yr for IUSB.
Performance
SPMB vs. IUSB - Performance Comparison
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Returns By Period
In the year-to-date period, SPMB achieves a 0.65% return, which is significantly higher than IUSB's 0.56% return. Over the past 10 years, SPMB has underperformed IUSB with an annualized return of 1.26%, while IUSB has yielded a comparatively higher 1.97% annualized return.
SPMB
- 1D
- 0.14%
- 1M
- 0.22%
- YTD
- 0.65%
- 6M
- 0.95%
- 1Y
- 6.29%
- 3Y*
- 4.42%
- 5Y*
- 0.31%
- 10Y*
- 1.26%
IUSB
- 1D
- 0.13%
- 1M
- 0.26%
- YTD
- 0.56%
- 6M
- 0.63%
- 1Y
- 5.05%
- 3Y*
- 4.56%
- 5Y*
- 0.47%
- 10Y*
- 1.97%
SPMB vs. IUSB - Yearly Performance Comparison
| 2026 (YTD) | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | |
|---|---|---|---|---|---|---|---|---|---|---|
SPMB SPDR Portfolio Mortgage Backed Bond ETF | 0.65% | 8.29% | 1.35% | 5.09% | -12.05% | -1.46% | 4.19% | 6.16% | 1.01% | 2.13% |
IUSB iShares Core Universal USD Bond ETF | 0.56% | 7.38% | 2.11% | 6.23% | -13.04% | -1.33% | 7.62% | 9.13% | -0.27% | 3.82% |
Correlation
The correlation between SPMB and IUSB is 0.95 - 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 | 0.95 |
Correlation (3Y) Calculated over the trailing 3-year period | 0.96 |
Correlation (5Y) Calculated over the trailing 5-year period | 0.94 |
Correlation (10Y) Calculated over the trailing 10-year period | 0.80 |
Correlation (All Time) Calculated using the full available price history since Jun 13, 2014 | 0.73 |
Over the past year, SPMB and IUSB have become more correlated (0.95) than their long-term average of 0.73, meaning their price movements have been converging.
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Return for Risk
SPMB vs. IUSB — Risk / Return Rank
SPMB
IUSB
SPMB vs. IUSB - Risk-Adjusted Trends Comparison
This table presents a comparison of risk-adjusted performance metrics for SPDR Portfolio Mortgage Backed Bond ETF (SPMB) and iShares Core Universal USD Bond ETF (IUSB). 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.
| SPMB | IUSB | Difference | |
|---|---|---|---|
| Sharpe ratioReturn per unit of total volatility | +0.07 | ||
| Sortino ratioReturn per unit of downside risk | +0.11 | ||
| Omega ratioGain probability vs. loss probability | 1.27 | 1.25 | +0.02 |
| Calmar ratioReturn relative to maximum drawdown | 2.19 | 2.01 | +0.18 |
| Martin ratioReturn relative to average drawdown | 7.16 | 6.08 | +1.08 |
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
| SPMB | IUSB | Difference | |
|---|---|---|---|
Sharpe Ratio (1Y)Calculated over the trailing 1-year period | 1.49 | 1.42 | +0.07 |
Sharpe Ratio (5Y)Calculated over the trailing 5-year period | 0.05 | 0.08 | -0.03 |
Sharpe Ratio (10Y)Calculated over the trailing 10-year period | 0.17 | 0.39 | -0.23 |
Sharpe Ratio (All Time)Calculated using the full available price history | 0.34 | 0.46 | -0.12 |
Drawdowns
SPMB vs. IUSB - Drawdown Comparison
The maximum SPMB drawdown since its inception was -18.03%, roughly equal to the maximum IUSB drawdown of -17.90%. Use the drawdown chart below to compare losses from any high point for SPMB and IUSB.
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Drawdown Indicators
| SPMB | IUSB | Difference | |
|---|---|---|---|
Max DrawdownLargest peak-to-trough decline | -18.03% | -17.90% | -0.13% |
Max Drawdown (1Y)Largest decline over 1 year | -2.89% | -2.53% | -0.36% |
Max Drawdown (3Y)Largest decline over 3 years | -7.66% | -5.82% | -1.84% |
Max Drawdown (5Y)Largest decline over 5 years | -17.49% | -17.87% | +0.38% |
Max Drawdown (10Y)Largest decline over 10 years | -18.03% | -17.90% | -0.13% |
Current DrawdownCurrent decline from peak | -1.45% | -1.20% | -0.25% |
Average DrawdownAverage peak-to-trough decline | -2.85% | -3.59% | +0.74% |
Ulcer IndexDepth and duration of drawdowns from previous peaks | 0.88% | 0.83% | +0.05% |
Volatility
SPMB vs. IUSB - Volatility Comparison
SPDR Portfolio Mortgage Backed Bond ETF (SPMB) has a higher volatility of 1.58% compared to iShares Core Universal USD Bond ETF (IUSB) at 1.24%. This indicates that SPMB's price experiences larger fluctuations and is considered to be riskier than IUSB based on this measure. The chart below showcases a comparison of their rolling one-month volatility.
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Volatility by Period
| SPMB | IUSB | Difference | |
|---|---|---|---|
Volatility (1M)Calculated over the trailing 1-month period | 1.58% | 1.24% | +0.34% |
Volatility (6M)Calculated over the trailing 6-month period | 3.08% | 2.62% | +0.46% |
Volatility (1Y)Calculated over the trailing 1-year period | 4.28% | 3.62% | +0.66% |
Volatility (5Y)Calculated over the trailing 5-year period, annualized | 6.77% | 5.79% | +0.98% |
Volatility (10Y)Calculated over the trailing 10-year period, annualized | 7.61% | 5.04% | +2.57% |
SPMB vs. IUSB - Expense Ratio Comparison
SPMB has a 0.04% expense ratio, which is lower than IUSB'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. IUSB - Dividend Comparison
SPMB's dividend yield for the trailing twelve months is around 4.08%, less than IUSB's 4.23% yield.
| Position | TTM | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
IUSB iShares Core Universal USD Bond ETF | 4.23% | 4.17% | 4.04% | 3.46% | 2.53% | 1.74% | 2.68% | 3.04% | 2.98% | 2.56% | 2.60% | 1.95% |
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
With a correlation of 0.95, SPMB and IUSB 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.
SPMB has higher volatility (1.58%) compared to IUSB (1.24%). In terms of maximum drawdown, SPMB dropped -18.03% vs IUSB's -17.90%.
On 10-year performance, IUSB leads with 1.97% vs 1.26% for SPMB. On fees, SPMB is cheaper at 0.04% per year. On volatility, IUSB has been the lower-risk option at 1.24%. The better choice depends on whether you care most about return, fees, risk, or income.
Over the 10-year period, IUSB has performed better with a 1.97% return vs 1.26%. 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 IUSB.
IUSB has the higher dividend yield at 4.23%, compared with 4.08% for SPMB.
SPMB is categorized as Mortgage Backed Securities, while IUSB is Intermediate Core-Plus Bond. SPMB tracks Bloomberg US Aggregate Securitized - MBS, while IUSB tracks Bloomberg U.S. Universal Index. They also come from different issuers: State Street and iShares. Their fees differ too: 0.04% for SPMB and 0.06% for IUSB.
SPMB currently has the higher Sharpe Ratio (1.49 vs 1.42), 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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