MBB Performance — iShares MBS ETF
Data updated: 2026-07-24
MBB returned +0.82% year to date and +6.79% over one year to May 2026. Annualised returns are +4.35% over 3 years and +0.42% over 5 years. Against its Intermediate Securitized Bond category average the fund came out behind over three years but ahead over one: $100 invested three years ago grew to $114, against $116 for the category, and to $107 over one year, against $106. Volatility over the past three years was 6.38% a year. In the 12 months to May 2026 the fund lost a net $450.6M, and assets reached $38.74B.
MBB Growth of $100
What $100 invested in iShares MBS ETF grew to, compounded from monthly returns reported on SEC Form N-PORT, against the Intermediate Securitized Bond category average over the same months.
| Period | MBB | Category average |
|---|---|---|
| 1 year (Jun 2025 – May 2026) | $107 | $106 |
| 3 years (Jun 2023 – May 2026) | $114 | $116 |
| 5 years (Jun 2021 – May 2026) | $102 | $105 |
| Since data start (Sep 2019 – May 2026) | $106 | $111 |
MBB Trailing Returns
Total returns to May 2026, from SEC N-PORT.
| Period | Total return |
|---|---|
| YTD | +0.82% |
| 1 year | +6.79% |
| 3 years (annualised) | +4.35% |
| 5 years (annualised) | +0.42% |
MBB Annual Returns
Calendar-year total returns of iShares MBS ETF, compounded from monthly SEC N-PORT returns. Partial years show the months covered.
| Year | Total return |
|---|---|
| 2026 (Jan–May) | +0.82% |
| 2025 | +8.44% |
| 2024 | +1.33% |
| 2023 | +4.98% |
| 2022 | −11.85% |
| 2021 | −1.27% |
| 2020 | +4.02% |
| 2019 (Sep–Dec) | +0.64% |
MBB Monthly Returns
Monthly total returns as reported on SEC Form N-PORT.
| Year | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2026 | +0.5% | +1.6% | −1.6% | +0.1% | +0.3% | — | — | — | — | — | — | — |
| 2025 | +0.5% | +2.5% | 0.0% | +0.3% | −0.9% | +1.8% | −0.4% | +1.6% | +1.2% | +0.9% | +0.6% | +0.1% |
| 2024 | −0.4% | −1.6% | +0.9% | −2.9% | +2.0% | +1.2% | +2.6% | +1.6% | +1.2% | −2.8% | +1.4% | −1.7% |
| 2023 | +3.4% | −2.6% | +1.9% | +0.5% | −0.8% | −0.4% | −0.1% | −0.9% | −3.1% | −2.2% | +5.3% | +4.2% |
| 2022 | −1.5% | −1.0% | −2.6% | −3.5% | +1.1% | −1.6% | +3.1% | −3.3% | −5.0% | −1.4% | +4.1% | −0.6% |
| 2021 | +0.1% | −0.7% | −0.6% | +0.5% | −0.3% | 0.0% | +0.6% | −0.2% | −0.4% | −0.3% | −0.1% | −0.1% |
| 2020 | +0.7% | +1.1% | +0.8% | +0.9% | +0.2% | −0.1% | +0.2% | +0.1% | −0.1% | 0.0% | +0.1% | +0.2% |
| 2019 | — | — | — | — | — | — | — | — | +0.1% | +0.3% | 0.0% | +0.3% |
MBB Risk
Risk measures from monthly returns over Jun 2023 – May 2026.
- 3-year volatility (annualised): 6.38%
- 3-year Sharpe ratio: -0.02 (vs 4.5% risk-free rate)
- Best month: +5.29% (Nov 2023)
- Worst month: −3.12% (Sep 2023)
MBB Fund Flows
Monthly money in and out of iShares MBS ETF, from SEC Form N-PORT.
- 12-month net flow: −$450.6M
- 12-month gross sales (incl. reinvestments): $3.7B
- Sales ÷ redemptions: 0.89×
| Month | Sales | Redemptions | Net flow |
|---|---|---|---|
| May 2026 | $450.8M | $0 | $450.8M |
| Apr 2026 | $0 | $343.1M | −$343.1M |
| Mar 2026 | $0 | $286.4M | −$286.4M |
| Feb 2026 | $0 | $0 | $0 |
| Jan 2026 | $352.7M | $248.7M | $103.9M |
| Dec 2025 | $0 | $142.8M | −$142.8M |
| Nov 2025 | $0 | $2.5B | −$2.5B |
| Oct 2025 | $475.6M | $641.8M | −$166.2M |
| Sep 2025 | $380.7M | $0 | $380.7M |
| Aug 2025 | $505.4M | $0 | $505.4M |
| Jul 2025 | $977.6M | $0 | $977.6M |
| Jun 2025 | $554.9M | $0 | $554.9M |
MBB Assets Under Management
Net assets of iShares MBS ETF by report date, from SEC N-PORT filings.
| Report date | Net assets |
|---|---|
| 2026-05-31 | $38.74B |
| 2026-02-28 | $39.82B |
| 2025-11-30 | $39.41B |
| 2025-08-31 | $41.02B |
| 2025-05-31 | $38.23B |
| 2025-02-28 | $37.65B |
| 2024-11-30 | $35.65B |
| 2024-08-31 | $33.45B |
| 2024-05-31 | $30.50B |
| 2024-02-29 | $27.88B |
| 2023-11-30 | $27.96B |
| 2023-08-31 | $26.64B |
For information only. Not investment advice: figures are as reported in SEC filings and may contain errors or be out of date. Past performance does not guarantee future results.