IMBA.L vs. MBB
IMBA.L (iShares US Mortgage Backed Securities UCITS ETF (Acc)) and MBB (iShares MBS Bond ETF) are both Mortgage Backed Securities funds from iShares - IMBA.L tracks the Bloomberg US Mortgage Backed Securities Index while MBB tracks the Barclays Capital U.S. MBS Index. Both are passively managed. Over the past 5 years, IMBA.L returned 0.11%/yr vs 0.36%/yr for MBB. A 0.58 correlation means they provide meaningful diversification when combined. IMBA.L charges 0.28%/yr vs 0.06%/yr for MBB.
Performance
IMBA.L vs. MBB - Performance Comparison
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Returns By Period
In the year-to-date period, IMBA.L achieves a 0.11% return, which is significantly lower than MBB's 0.68% return.
IMBA.L
- 1D
- 0.04%
- 1M
- -0.14%
- YTD
- 0.11%
- 6M
- 0.85%
- 1Y
- 6.02%
- 3Y*
- 4.11%
- 5Y*
- 0.11%
- 10Y*
- —
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%
IMBA.L vs. MBB - Yearly Performance Comparison
| 2026 (YTD) | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | |
|---|---|---|---|---|---|---|---|---|---|---|
IMBA.L iShares US Mortgage Backed Securities UCITS ETF (Acc) | 0.11% | 8.36% | 1.51% | 3.65% | -11.44% | -1.51% | 3.69% | 6.24% | 0.55% | 0.92% |
MBB iShares MBS Bond ETF | 0.68% | 8.38% | 1.31% | 5.01% | -11.74% | -1.43% | 4.08% | 6.18% | 0.82% | 1.17% |
Correlation
The correlation between IMBA.L and MBB is 0.58, which is moderate. They share some common price drivers but move independently often enough to provide real diversification benefit when combined.
| Correlation | |
|---|---|
Correlation (1Y) Calculated over the trailing 1-year period | 0.58 |
Correlation (3Y) Calculated over the trailing 3-year period | 0.65 |
Correlation (5Y) Calculated over the trailing 5-year period | 0.64 |
Correlation (All Time) Calculated using the full available price history since Apr 17, 2017 | 0.58 |
The correlation between IMBA.L and MBB has been stable across timeframes, ranging from 0.58 to 0.65 - a consistent structural relationship.
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Return for Risk
IMBA.L vs. MBB — Risk / Return Rank
IMBA.L
MBB
IMBA.L vs. MBB - Risk-Adjusted Trends Comparison
This table presents a comparison of risk-adjusted performance metrics for iShares US Mortgage Backed Securities UCITS ETF (Acc) (IMBA.L) 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.
| IMBA.L | MBB | Difference | |
|---|---|---|---|
| Sharpe ratioReturn per unit of total volatility | -0.17 | ||
| Sortino ratioReturn per unit of downside risk | -0.21 | ||
| Omega ratioGain probability vs. loss probability | 1.22 | 1.25 | -0.03 |
| Calmar ratioReturn relative to maximum drawdown | 1.85 | 2.10 | -0.26 |
| Martin ratioReturn relative to average drawdown | 6.41 | 6.96 | -0.55 |
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
| IMBA.L | MBB | Difference | |
|---|---|---|---|
Sharpe Ratio (1Y)Calculated over the trailing 1-year period | 1.22 | 1.39 | -0.17 |
Sharpe Ratio (5Y)Calculated over the trailing 5-year period | 0.02 | 0.05 | -0.04 |
Sharpe Ratio (10Y)Calculated over the trailing 10-year period | — | 0.25 | — |
Sharpe Ratio (All Time)Calculated using the full available price history | 0.20 | 0.59 | -0.38 |
Drawdowns
IMBA.L vs. MBB - Drawdown Comparison
The maximum IMBA.L drawdown since its inception was -18.05%, roughly equal to the maximum MBB drawdown of -17.64%. Use the drawdown chart below to compare losses from any high point for IMBA.L and MBB.
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Drawdown Indicators
| IMBA.L | MBB | Difference | |
|---|---|---|---|
Max DrawdownLargest peak-to-trough decline | -18.05% | -17.64% | -0.41% |
Max Drawdown (1Y)Largest decline over 1 year | -3.24% | -2.94% | -0.30% |
Max Drawdown (3Y)Largest decline over 3 years | -7.48% | -7.68% | +0.20% |
Max Drawdown (5Y)Largest decline over 5 years | -17.67% | -17.19% | -0.48% |
Max Drawdown (10Y)Largest decline over 10 years | — | -17.64% | — |
Current DrawdownCurrent decline from peak | -1.60% | -1.42% | -0.18% |
Average DrawdownAverage peak-to-trough decline | -4.49% | -2.35% | -2.14% |
Ulcer IndexDepth and duration of drawdowns from previous peaks | 0.94% | 0.89% | +0.05% |
Volatility
IMBA.L vs. MBB - Volatility Comparison
iShares US Mortgage Backed Securities UCITS ETF (Acc) (IMBA.L) has a higher volatility of 1.82% compared to iShares MBS Bond ETF (MBB) at 1.58%. This indicates that IMBA.L's price experiences larger fluctuations and is considered to be riskier than MBB based on this measure. The chart below showcases a comparison of their rolling one-month volatility.
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Volatility by Period
| IMBA.L | MBB | Difference | |
|---|---|---|---|
Volatility (1M)Calculated over the trailing 1-month period | 1.82% | 1.58% | +0.24% |
Volatility (6M)Calculated over the trailing 6-month period | 3.72% | 3.23% | +0.49% |
Volatility (1Y)Calculated over the trailing 1-year period | 4.91% | 4.51% | +0.40% |
Volatility (5Y)Calculated over the trailing 5-year period, annualized | 7.18% | 6.81% | +0.37% |
Volatility (10Y)Calculated over the trailing 10-year period, annualized | 5.75% | 5.31% | +0.44% |
IMBA.L vs. MBB - Expense Ratio Comparison
IMBA.L has a 0.28% expense ratio, which is higher than MBB's 0.06% expense ratio.
Dividends
IMBA.L vs. MBB - Dividend Comparison
IMBA.L has not paid dividends to shareholders, while MBB's dividend yield for the trailing twelve months is around 4.27%.
| Position | TTM | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
IMBA.L iShares US Mortgage Backed Securities UCITS ETF (Acc) | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% |
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
IMBA.L and MBB have a correlation of 0.58, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.
On fees, MBB is cheaper at 0.06% per year. The better choice depends on whether you care most about return, fees, risk, or income.
MBB is cheaper with a 0.06% expense ratio, compared with 0.28% for IMBA.L.
IMBA.L tracks Bloomberg US Mortgage Backed Securities Index, while MBB tracks Barclays Capital U.S. MBS Index. Their fees differ too: 0.28% for IMBA.L and 0.06% for MBB.
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