VANGUARD MORTGAGE-BACKED SECURITIES INDEX FUND
U.S. bond index ETF · tracks Bloomberg U.S. MBS Float Adjusted Index
As of its 2026 Q2 report, VANGUARD MORTGAGE-BACKED SECURITIES INDEX FUND held 5,123 positions with $17.05B in net assets. Its ten largest holdings made up 8.0% of the fund. The VMBS share class costs 0.03% a year. Over the 12 months to May 2026, VMBS returned 6.8%, with dividends reinvested. In 2026 Q2 it added 139 new positions and exited 40.
Vanguard Mortgage-Backed Securities Index Fund (the Fund) seeks to track the performance of a market-weighted mortgage-backed securities index.
The fund tracks the Bloomberg U.S. MBS Float Adjusted Index using a sampling approach, holding a range of mortgage-backed securities issued by Ginnie Mae, Fannie Mae, and Freddie Mac that collectively approximate the index's risk factors and characteristics. Because the fund samples rather than holds all index constituents, its returns may diverge from the index.
What you own
| Company | Weight | Value | Shares |
|---|---|---|---|
Vanguard Cmt Funds-Vanguard Market Liquidity Fund | 5.08% | $866.41M | — |
Fannie Mae or Freddie Mac 2.00% · due 2026-06-11 | 0.52% | $89.14M | — |
Ginnie Mae II Pool 5.50% · due 2026-07-20 | 0.36% | $61.66M | — |
Ginnie Mae II Pool 5.00% · due 2054-11-20 | 0.32% | $54.53M | — |
Ginnie Mae II Pool 5.00% · due 2056-01-20 | 0.31% | $53.12M | — |
Fannie Mae Pool 5.50% · due 2056-03-01 | 0.29% | $50.20M | — |
Ginnie Mae II Pool 5.00% · due 2056-02-20 | 0.29% | $49.19M | — |
Ginnie Mae II Pool 5.50% · due 2026-06-22 | 0.29% | $49.15M | — |
Ginnie Mae II Pool 4.50% · due 2054-11-20 | 0.28% | $48.13M | — |
Freddie Mac Pool 2.00% · due 2052-02-01 | 0.28% | $46.80M | — |
The 200 largest of 5,123 holdings, with the share counts as filed, open with a free account.
What the fund is made of
Percentages are of fund net assets. Rounding, liabilities and short positions can make totals differ from 100%.
| Securitized | 97.79% |
| Cash & short-term | 5.08% |
How it has done
VMBS share class · total returns with dividends reinvested
Volatility over the last 12 months: 3.22%. Past returns are a record, not a forecast.
The 3 share classes hold the same portfolio
| Share class | Expense ratio | 1 year | 3 years | 5 years | Worst fall |
|---|---|---|---|---|---|
| 0.04% | +6.77% | +14.16% | +2.52% | -6.30% | |
| 0.02% | +6.79% | +14.18% | +2.66% | -6.32% | |
| 0.03% | +6.79% | +14.20% | +2.66% | -6.27% |
These classes hold the same portfolio, so the 0.14pp spread over 5 years is the cost difference between them — roughly 0.03pp a year — not a difference in what they own.
Fees & fund details
VANGUARD MORTGAGE-BACKED SECURITIES INDEX FUND is a U.S. bond index ETF that tracks the Bloomberg U.S. MBS Float Adjusted Index.
- Asset class
- Bonds
- Region
- United States
- Management
- Index (passive)
- Fund type
- ETF
- Credit quality
- Investment grade
- Rate sensitivity
- Intermediate duration
- Expense ratio, by class
- 0.02% – 0.04%· VMBS 0.03%
- Portfolio turnover
- 91.00% a year · as of 2026 Q2
Turnover is how much of the portfolio was replaced in a year.
Classified from what the fund holds, not from its name · 2026 Q2. The summary is a paraphrase of the prospectus; the objective is verbatim.
What changed this quarter
Positions that entered or left the fund since its previous filing. Positions that were only resized are not listed.
139 new· the largest 4
40 exited· the largest 2
Debt profile
What this fund holds — value-weighted across its bond and securitized long positions · as of 2026-05-31
Share of the fund's debt by how its coupon behaves — the fact that decides whether a rate move reaches this portfolio at all.
| Fixed rate | 100.0% |
| Floating rate | 0.0% |
Share of the fund's debt value in each maturity band, shortest first.
| <1y | 3.5% |
| 1-3y | 0.1% |
| 3-5y | 0.1% |
| 5-10y | 2.7% |
| 10y+ | 93.7% |
Based on what filers reported; a filer that never reported a flag also reads as none.
Risk profile
Interest-rate and credit-spread sensitivity, both in years · as of 2026Q2
Most of this fund’s sensitivity is to interest rates, with credit spreads carrying nearly as much.
Where the loss would come from. The two shocks are the same size, so this is the balance of the fund's two sensitivities rather than a bet on one moving more.
| Interest rates | 56% |
| Credit spreads | 44% |
Filers report the impact of a 0.01% move only, so the total is our own scaling of that one number and overstates the loss on most bonds — read it as approximate, never as precise. The two sensitivities overlap rather than add up: they measure the same positions against different shocks, which is why the durations above are shown side by side and never summed.
Share of the fund's spread duration carried by each credit tier.
| Investment grade | +4.14 yr |
Share of duration at each point, shortest first. A positive figure loses value when spreads widen; a negative one offsets — a credit hedge.
| 3 mo | 0.03 yr | 1% |
| 1 yr | 0.55 yr | 11% |
| 5 yr | 1.45 yr | 28% |
| 10 yr | 2.50 yr | 48% |
| 30 yr | 0.68 yr | 13% |
| 3 mo | 0.02 yr | 1% |
| 1 yr | 0.41 yr | 10% |
| 5 yr | 1.15 yr | 28% |
| 10 yr | 2.01 yr | 49% |
| 30 yr | 0.54 yr | 13% |
The two bands measure the same positions against different shocks and do not add — a Treasury carries rate duration and no spread duration, a floating-rate credit the reverse. Rate tenors are also summed across every currency the fund discloses.
Show the numbers
| Tenor | Rate yrs | IG yrs | HY yrs | IG $/bp | HY $/bp |
|---|---|---|---|---|---|
| 3 mo | +0.03 | +0.02 | +0.00 | $41.4k | $0 |
| 1 yr | +0.55 | +0.41 | +0.00 | $704.9k | $0 |
| 5 yr | +1.45 | +1.15 | +0.00 | $1.97m | $0 |
| 10 yr | +2.50 | +2.01 | +0.00 | $3.43m | $0 |
| 30 yr | +0.68 | +0.54 | +0.00 | $921.4k | $0 |
Dollar change per 1bp of spread movement, as filed and sign-anchored. A blank cell was not filed; a zero was.
Understand how this fund fits with the rest.
Explore shared holdings, compare funds and follow their businesses with your connected AI:
- “Where do my funds overlap — VMBS, QQQ and the fund in my 401(k)?”
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