# iShares US Mortgage Backed Securities UCITS ETF Acc (IMBA)

**Source:** https://fundology.uk/fund/imba · ISIN IE00BYXYYN70 · Data: TradingView (LSE closes and returns, delayed), issuer documents and holdings (iShares), ONS CPIH, FCA FIRDS

## At a glance

> Capital at risk. Past performance is not a guide to future returns. The value of investments can fall as well as rise.

As of 01/10/2026, IMBA (iShares US Mortgage Backed Securities UCITS ETF Acc, ISIN IE00BYXYYN70) closed at $5.38 on the London Stock Exchange. Its ongoing charge is 0.28% a year (about £28 on £10,000). Over the five years to 01/10/2026 its total return was −1.1%, or −22.7% after UK CPIH inflation.

## Summary

iShares US Mortgage Backed Securities UCITS ETF Acc is an exchange-traded fund (ETF) from iShares, launched in 2017. It tracks the Bloomberg U.S. MBS Index. You buy and sell it through a share-dealing account or platform during stock-market hours, like a share. Its ongoing charge is 0.28% a year — about £28 a year on every £10,000 invested, taken from the fund's value rather than billed to you. Income from its investments is reinvested inside the fund, so it shows up as a rising price rather than cash paid to you.

Latest close: **$5.38** (01/10/2026).

## Key facts

| Fact | Value |
|---|---|
| Ticker (LSE) | IMBA |
| ISIN | IE00BYXYYN70 |
| Category | Corporate & other bonds |
| Type | ETF |
| Provider | iShares |
| Tracks | Bloomberg U.S. MBS Index |
| Income | Accumulating |
| Ongoing charge | 0.28% a year (£28 per £10,000) |
| Fund size | £1.6bn |
| Launched | 2017 |
| Domicile | Ireland |

## Past returns (periods to 01/10/2026)

After the fund's ongoing charges. "Income reinvested" is total return; "price only" leaves out income paid out. Real returns are after ONS CPIH inflation.

| Window | Return | After CPIH inflation | Measured as |
|---|---|---|---|
| 1 year | -0.24% | -3.37% | income reinvested |
| 3 years | +5.76% | -4.57% | income reinvested |
| 5 years | -1.09% | -22.68% | income reinvested |

Returns: TradingView (delayed data). Inflation: ONS CPIH, latest month published.

## Calendar-year returns

Calendar-year returns of iShares US Mortgage Backed Securities UCITS ETF Acc in pounds (price, with income reinvested in the fund): 2022 −0.7%, 2023 −2.0%, 2024 +2.6%, 2025 +0.6%; 2026 to 01/10/2026 −1.1%. Returns of iShares US Mortgage Backed Securities UCITS ETF Acc in pounds (price, with income reinvested in the fund) over the 12 months to 30/09/2026: −1.7%; to 30/09/2025: +3.0%; to 30/09/2024: +2.6%; to 30/09/2023: −10.5%; to 30/09/2022: +7.3%.

| Year | Return | After CPIH inflation | Measured as |
|---|---|---|---|
| 2022 | -0.7% | -9.1% | Price |
| 2023 | -2.0% | -5.9% | Price |
| 2024 | +2.6% | -0.9% | Price |
| 2025 | +0.6% | -2.9% | Price |
| 2026 to 01/10/2026 | -1.1% | -3.9% | Price |

## Risk metrics

| Window | Volatility | Max drawdown |
|---|---|---|
| 1 year | 6.91% | -4.63% |
| 3 years | 7.51% | -8.43% |
| 5 years | 8.05% | -12.82% |

## Largest fall

Volatility of iShares US Mortgage Backed Securities UCITS ETF Acc in pounds, annualised from weekly returns to 01/10/2026: 6.9% over 1 year, 7.5% over 3 years, 8.1% over 5 years. Largest fall in the price of iShares US Mortgage Backed Securities UCITS ETF Acc since October 2021, in pounds: −12.8% from 30/09/2022 to 14/07/2023. The lowest 12-month return of iShares US Mortgage Backed Securities UCITS ETF Acc in pounds (price, with income reinvested in the fund) since January 2021 was −11.4% (12 months to 14/07/2023); the highest was +9.7% (12 months to 26/06/2026). On 01/10/2026 the price of iShares US Mortgage Backed Securities UCITS ETF Acc was 6.3% below its highest weekly close since October 2021 (30/09/2022), in pounds.

## Charges compared with similar funds

Ongoing charge of iShares US Mortgage Backed Securities UCITS ETF Acc 0.28% a year, as of 02/10/2026: 157 of the 392 other corporate and other bond funds charge more, 2 the same and 233 less (share classes counted once).

## Funds tracking the same index

3 funds track Bloomberg U.S. MBS Index, this one included and share classes counted once; their ongoing charges range from 0.28% to 0.30% a year (01/10/2026).

| Fund | Ongoing charge | 1 year | 3 years | 5 years |
|---|---|---|---|---|
| iShares US Mortgage Backed Securities UCITS ETF Acc (this fund) | 0.28% | -0.2% | +5.8% | -1.1% |
| iShares US Mortgage Backed Securities UCITS ETF Hedged GBP | 0.30% | -2.1% | +4.1% | — |
| iShares US Mortgage Backed Securities UCITS ETF USD | 0.28% | -0.7% | +4.1% | -2.2% |

Returns are the data vendor’s, in pounds, income reinvested unless marked "(price)".

## Charges & eligibility

- Ongoing charges figure (OCF): **0.28%** per year
- ISA eligible: yes
- SIPP eligible: yes

## What it holds

As of 30/09/2026, IMBA holds 612 positions, according to the holdings iShares publishes. The largest is Blk Ics USD Leaf Agency Dist at 9.03% of the fund; the ten largest make up 35.8%.

### Top holdings

Largest positions (as of 30/09/2026), as a percentage of the whole fund:

| # | Holding | Ticker | Weight |
|---|---|---|---|
| 1 | Blk Ics USD Leaf Agency Dist | — | 9.03% |
| 2 | Fhlmc 30YR Umbs 2.00% 01/02/2051 | — | 8.59% |
| 3 | Fnma 30YR Umbs 2.50% 01/08/2051 | — | 3.79% |
| 4 | Fnma 30YR Umbs 2.00% 01/12/2050 | — | 3.30% |
| 5 | Fnma 30YR Umbs Super 2.50% 01/02/2051 | — | 2.77% |
| 6 | GNMA2 30YR 2021 Production 2.00% 20/10/2051 | — | 2.15% |
| 7 | GNMA2 30YR 2021 Production 2.50% 20/02/2051 | — | 1.94% |
| 8 | Fnma 30YR Umbs 4.50% 01/09/2052 | — | 1.46% |
| 9 | GNMA2 30YR 2024 Production 5.00% 20/11/2054 | — | 1.41% |
| 10 | Fnma 30YR Umbs 2.50% 01/04/2052 | — | 1.40% |

Source: iShares, holdings as published, as of 30/09/2026.

## Where it invests

Shares of the whole fund. Bonds, cash and positions the source does not classify are shown as they come, not guessed.

### By sector

As published by iShares, as of 30/09/2026.

| Sector | Weight |
|---|---|
| MBS Pass-Through | 99.9% |
| Cash and derivatives | 0.1% |

### By type of asset

Added up from the holdings iShares publishes, as of 30/09/2026.

| Type of asset | Weight |
|---|---|
| Bonds | 99.7% |
| Cash and money market | 9.1% |

The 447 holdings on record (of 612 iShares reports): https://fundology.uk/fund/imba/holdings

## Questions people ask

**What is the ongoing charge of IMBA?**

The ongoing charge of IMBA is 0.28% a year — about £28 a year on every £10,000 invested, taken from the fund’s value rather than billed to you. Platform and dealing fees are charged separately. Ongoing charge of iShares US Mortgage Backed Securities UCITS ETF Acc 0.28% a year, as of 02/10/2026: 157 of the 392 other corporate and other bond funds charge more, 2 the same and 233 less (share classes counted once).

**What does IMBA track?**

IMBA tracks the Bloomberg U.S. MBS Index.

**Is IMBA accumulating or distributing?**

IMBA is accumulating: income is reinvested inside the fund, so it shows up as a rising price rather than cash paid to you.

**What is the ISIN of IMBA?**

The ISIN of IMBA is IE00BYXYYN70. An ISIN identifies one exact share class of a fund; IMBA is its ticker on the London Stock Exchange.

**What does IMBA hold?**

As of 30/09/2026, IMBA holds 612 positions, according to the holdings iShares publishes. The largest is Blk Ics USD Leaf Agency Dist at 9.03% of the fund; the ten largest make up 35.8%. Its ten largest holdings are Blk Ics USD Leaf Agency Dist (9.03%), Fhlmc 30YR Umbs 2.00% 01/02/2051 (8.59%), Fnma 30YR Umbs 2.50% 01/08/2051 (3.79%), Fnma 30YR Umbs 2.00% 01/12/2050 (3.30%), Fnma 30YR Umbs Super 2.50% 01/02/2051 (2.77%), GNMA2 30YR 2021 Production 2.00% 20/10/2051 (2.15%), GNMA2 30YR 2021 Production 2.50% 20/02/2051 (1.94%), Fnma 30YR Umbs 4.50% 01/09/2052 (1.46%), GNMA2 30YR 2024 Production 5.00% 20/11/2054 (1.41%) and Fnma 30YR Umbs 2.50% 01/04/2052 (1.40%).

**What were IMBA’s returns in each of the last five years?**

Calendar-year returns of IMBA in pounds (price, with income reinvested in the fund): 2022 −0.7%, 2023 −2.0%, 2024 +2.6%, 2025 +0.6%; 2026 to 01/10/2026 −1.1%. Past performance is not a guide to future returns.

**How has IMBA done after inflation?**

Over the five years to 01/10/2026 IMBA’s total return was −1.1%, or −22.7% after UK CPIH inflation. Past performance is not a guide to future returns.

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Capital at risk. Past performance is not a guide to future returns. The value of investments can fall as well as rise.