VMBSX Performance — Vanguard Mortgage-Backed Securities Index Fund, Admiral Shares
Data updated: 2026-07-29
VMBSX returned +0.95% year to date and +6.77% over one year to May 2026. Annualised returns are +4.51% over 3 years and +0.50% 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 6.28% a year. In the 12 months to May 2026 the fund took in a net $620.9M, and assets reached $17.05B.
VMBSX Growth of $100
What $100 invested in Vanguard Mortgage-Backed Securities Index Fund grew to, compounded from monthly returns reported on SEC Form N-PORT, against the Intermediate Securitized Bond category average over the same months.
| Period | VMBSX | Category average |
|---|---|---|
| 1 year (Jun 2025 – May 2026) | $107 | $106 |
| 3 years (Jun 2023 – May 2026) | $114 | $116 |
| 5 years (Jun 2021 – May 2026) | $103 | $105 |
| Since data start (Sep 2019 – May 2026) | $106 | $111 |
VMBSX Trailing Returns
Total returns to May 2026, from SEC N-PORT.
| Period | Total return |
|---|---|
| YTD | +0.95% |
| 1 year | +6.77% |
| 3 years (annualised) | +4.51% |
| 5 years (annualised) | +0.50% |
VMBSX Annual Returns
Calendar-year total returns of Vanguard Mortgage-Backed Securities Index Fund, compounded from monthly SEC N-PORT returns. Partial years show the months covered.
| Year | Total return |
|---|---|
| 2026 (Jan–May) | +0.95% |
| 2025 | +8.42% |
| 2024 | +1.44% |
| 2023 | +4.99% |
| 2022 | −11.56% |
| 2021 | −1.35% |
| 2020 | +3.74% |
| 2019 (Sep–Dec) | +0.83% |
VMBSX 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% | +0.3% | +0.2% | — | — | — | — | — | — | — |
| 2025 | +0.7% | +2.3% | 0.0% | +0.3% | −0.8% | +1.7% | −0.3% | +1.6% | +1.1% | +0.8% | +0.7% | +0.1% |
| 2024 | −0.4% | −1.6% | +1.1% | −3.0% | +2.0% | +1.2% | +2.5% | +1.5% | +1.2% | −2.7% | +1.3% | −1.6% |
| 2023 | +3.1% | −2.5% | +1.9% | +0.5% | −0.8% | −0.3% | 0.0% | −0.9% | −3.0% | −2.2% | +5.3% | +4.2% |
| 2022 | −1.4% | −1.0% | −2.6% | −3.6% | +1.1% | −1.6% | +3.2% | −3.2% | −5.1% | −1.4% | +4.2% | −0.4% |
| 2021 | 0.0% | −0.6% | −0.5% | +0.6% | −0.3% | −0.1% | +0.6% | −0.2% | −0.3% | −0.3% | −0.1% | −0.2% |
| 2020 | +0.7% | +0.9% | +1.6% | +0.2% | 0.0% | −0.1% | +0.1% | 0.0% | −0.1% | −0.1% | +0.1% | +0.3% |
| 2019 | — | — | — | — | — | — | — | — | +0.1% | +0.4% | +0.1% | +0.2% |
VMBSX Risk
Risk measures from monthly returns over Jun 2023 – May 2026.
- 3-year volatility (annualised): 6.28%
- 3-year Sharpe ratio: 0.00 (vs 4.5% risk-free rate)
- Best month: +5.32% (Nov 2023)
- Worst month: −3.02% (Sep 2023)
VMBSX Fund Flows
Monthly money in and out of Vanguard Mortgage-Backed Securities Index Fund, from SEC Form N-PORT.
- 12-month net flow: $620.9M
- 12-month gross sales (incl. reinvestments): $2.5B
- Sales ÷ redemptions: 1.33×
| Month | Sales | Redemptions | Net flow |
|---|---|---|---|
| May 2026 | $265.6M | $36.0M | $229.5M |
| Apr 2026 | $241.8M | $45.3M | $196.5M |
| Mar 2026 | $89.7M | $40.6M | $49.1M |
| Feb 2026 | $333.7M | $199.6M | $134.2M |
| Jan 2026 | $87.0M | $193.2M | −$106.2M |
| Dec 2025 | $521.7M | $23.2M | $498.5M |
| Nov 2025 | $34.8M | $53.4M | −$18.6M |
| Oct 2025 | $49.2M | $1.0B | −$974.6M |
| Sep 2025 | $549.8M | $17.3M | $532.5M |
| Aug 2025 | $50.7M | $90.5M | −$39.8M |
| Jul 2025 | $181.7M | $48.2M | $133.5M |
| Jun 2025 | $98.4M | $112.0M | −$13.7M |
VMBSX Assets Under Management
Net assets of Vanguard Mortgage-Backed Securities Index Fund by report date, from SEC N-PORT filings.
| Report date | Net assets |
|---|---|
| 2026-05-31 | $17.05B |
| 2026-02-28 | $16.93B |
| 2025-11-30 | $16.20B |
| 2025-08-31 | $16.41B |
| 2025-05-31 | $16.03B |
| 2025-02-28 | $21.74B |
| 2024-11-30 | $20.02B |
| 2024-08-31 | $19.82B |
| 2024-05-31 | $18.66B |
| 2024-02-29 | $18.69B |
| 2023-11-30 | $18.82B |
| 2023-08-31 | $17.81B |
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.