Bridge Builder Municipal Bond Fund
Actively managed U.S. bond fund
As of its 2026 Q2 report, Bridge Builder Municipal Bond Fund held 5,793 positions with $20.79B in net assets. Its ten largest holdings made up 3.6% of the fund. The BBMUX share class costs 0.12% a year. Over the 12 months to May 2026, BBMUX returned 6.5%, with dividends reinvested. In 2026 Q2 it added 361 new positions and exited 292.
The investment objective of the Bridge Builder Municipal Bond Fund (the Fund or the Municipal Bond Fund) is to provide current income exempt from federal tax,
The fund invests at least 80% of assets in municipal securities whose interest is exempt from federal income tax, with day-to-day management delegated to four sub-advisers—Baird, BlackRock, FIAM, and MacKay Shields—each employing distinct strategies ranging from duration-neutral relative-value approaches to top-down macro combined with bottom-up credit research. The fund may hold municipal securities rated below investment grade, also known as junk bonds, or unrated securities that a sub-adviser believes are of comparable quality to investment-grade instruments. Because returns depend on the security selections and sector positioning decisions made by the sub-advisers, performance will diverge from any single benchmark.
What you own
| Company | Weight | Value | Shares |
|---|---|---|---|
FIDELITY INV MMKT GOVT-INST | 0.94% | $195.56M | — |
SOUTHEAST ENERGY A 5% 10/01/30 5.00% · due 2030-10-01 | 0.46% | $94.71M | — |
KENTUCKY ST PUBLI V/R 01/01/55 5.00% floating · due 2055-01-01 | 0.37% | $77.64M | — |
CALIFORNIA CMNTY V/R 01/01/55 5.00% floating · due 2055-01-01 | 0.29% | $60.88M | — |
PUERTO RICO SA 4.329% 07/01/40 4.33% · due 2040-07-01 | 0.28% | $57.25M | — |
MIAMI-DADE CNTY FL 5% 10/01/32 5.00% · due 2032-10-01 | 0.26% | $54.75M | — |
CHICAGO IL BRD OF 6% 04/01/46 6.00% · due 2046-04-01 | 0.26% | $53.65M | — |
MAIN STREET ENERGY 5% 10/01/33 5.00% · due 2033-10-01 | 0.25% | $51.64M | — |
BLACK BELT ENERGY 5% 11/01/36 5.00% · due 2036-11-01 | 0.24% | $50.57M | — |
UNIV OF TEXAS TX V/R 08/01/56 1.45% floating · due 2056-08-01 | 0.24% | $50.00M | — |
The 200 largest of 5,793 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%.
| Bonds | 96.24% |
| Securitized | 1.51% |
| Cash & short-term | 1.04% |
| Derivatives | -0.34% |
The outer band is exposure held short — written against the portfolio rather than part of it, which is why it sits outside the ring and why the two are never netted into one figure.
Derivatives are shown at market value, not notional exposure.
How it has done
BBMUX share class · total returns with dividends reinvested
Volatility over the last 12 months: 3.49%. Past returns are a record, not a forecast.
Jun 2026 has been filed since the trailing figures were struck, so it is not in the table above or the curve — every figure here shares one cut-off, which is what makes them comparable with other funds.
Fees & fund details
Bridge Builder Municipal Bond Fund is an actively managed U.S. bond fund.
- Asset class
- Bonds
- Region
- United States
- Management
- Actively managed
- Fund type
- Open-end fund
- Credit quality
- Investment grade
- Rate sensitivity
- Intermediate duration
- Expense ratio, by class
- 0.12%· BBMUX 0.12%
- Portfolio turnover
- 37.00% a year · as of 2025 Q4
Net is what a holder pays after the adviser's contractual waiver; gross is before it. A waiver can expire.
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.
361 new· the largest 8
292 exited· the largest 8
Debt profile
What this fund holds — value-weighted across its bond and securitized long positions · as of 2026-06-30
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 | 80.3% |
| Floating rate | 19.7% |
Share of the fund's debt value in each maturity band, shortest first.
| <1y | 1.7% |
| 1-3y | 4.4% |
| 3-5y | 4.5% |
| 5-10y | 21.6% |
| 10y+ | 67.7% |
These three overlap — one holding can be in arrears and paying in kind at once — so they are shown separately and never summed.
Risk profile
Interest-rate and credit-spread sensitivity, both in years · as of 2026Q2
More of this fund’s sensitivity sits in credit spreads than in interest rates — a rate rally that comes with a credit selloff works against it.
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.
| Credit spreads | 54% |
| Interest rates | 46% |
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 | +5.37 yr |
| High yield | +0.08 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 | 0.02 yr | 0% |
| 1 yr | 0.30 yr | 6% |
| 5 yr | 1.92 yr | 41% |
| 10 yr | 2.27 yr | 48% |
| 30 yr | 0.18 yr | 4% |
| 3 mo | 0.25 yr | 5% |
| 1 yr | 0.33 yr | 6% |
| 5 yr | 2.20 yr | 40% |
| 10 yr | 2.54 yr | 47% |
| 30 yr | 0.13 yr | 2% |
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 | +0.02 | +0.25 | +0.00 | $526.2k | $843 |
| 1 yr | +0.30 | +0.33 | +0.01 | $677.4k | $14.0k |
| 5 yr | +1.92 | +2.17 | +0.03 | $4.51m | $64.4k |
| 10 yr | +2.27 | +2.50 | +0.03 | $5.21m | $63.9k |
| 30 yr | +0.18 | +0.12 | +0.01 | $247.1k | $18.8k |
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.
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