MUB — iShares National Muni Bond ETF
Data updated: 2026-10-22
MUB — iShares National Muni Bond ETF. 0.05% expense ratio · since 2007 · Intermediate Municipal Bond. Holdings, fees, performance and SEC filings.
MUB Fund Overview
MUB — iShares National Muni Bond ETF is a US ETF managed by BlackRock Fund Advisors, categorised as Intermediate Municipal Bond. MUB tracks the ICE AMT-Free US National Municipal Index. ABC INVEST provides holdings, performance, costs, cashflows, risk data, prospectus documents and SEC filings, sourced from SEC filings.
- Type: US ETF (index fund)
- Adviser: BlackRock Fund Advisors
- Trust: iSHARES TRUST
- Category: Intermediate Municipal Bond
- Minimum investment: none, traded on an exchange
- Benchmark: ICE AMT-Free US National Municipal Index
- Inception date: September 7, 2007
- Exchange: NYSE Arca
- Assets under management: $45,378,340,357
- 1-year return: 3.9%
- Ticker: MUB
- SEC CIK: 0001100663
- SEC series ID: S000018861
- Share class ID: C000052220
- CUSIP: 464288414
- ISIN: US4642884146
- FIGI: BBG000TC0WT9
- LEI: 549300H21FUYFQW9N157
About MUB
The iShares National Muni Bond ETF (MUB) seeks to track the investment results, before fees and expenses, of the ICE AMT-Free US National Municipal Index. It uses representative sampling to invest at least 80% of its assets in the index's component securities, primarily investment-grade U.S. municipal bonds whose interest is exempt from federal income tax and the federal alternative minimum tax. Listed on NYSE Arca since September 7, 2007, MUB costs 0.05% a year and returned 3.9% in the 12 months to August 31, 2026, based on monthly returns reported to the SEC on Form N-PORT, with 4.2% volatility.
MUB Holdings
Top 10 holdings of iShares National Muni Bond ETF by percentage of net assets, from the fund's latest SEC N-PORT filing.
| Holding | % of net assets |
|---|---|
| Board of Regents of the University of Texas System | 0.18% |
| San Antonio Water System | 0.15% |
| New York State Thruway Authority | 0.15% |
| New York State Dormitory Authority | 0.13% |
| Northwest Independent School District | 0.12% |
| Houston Higher Education Finance Corp. | 0.12% |
| State of New Jersey | 0.12% |
| Ohio State University (The) | 0.12% |
| State of Washington | 0.12% |
| State of California | 0.12% |
MUB Portfolio Allocation
Asset-class allocation of iShares National Muni Bond ETF by percentage of net assets, from the latest SEC N-PORT filing.
| Asset class | Allocation |
|---|---|
| Fixed Income | 97.4% |
| Cash & Equivalents | 2.1% |
MUB Performance
Total returns for MUB through August 2026, from SEC filings.
| Period | Total return |
|---|---|
| YTD | 0.07% |
| 1 year | 3.89% |
| 3 years (annualised) | 3.03% |
| 5 years (annualised) | 0.55% |
MUB Risk Information
Risk metrics for MUB, derived from monthly returns in SEC filings.
- 1-year volatility (annualised): 4.24%
MUB Costs and Fees
MUB costs about $5 per $10,000 invested per year in fund expenses.
- Net expense ratio: 0.05%
- Gross expense ratio: 0.05%
- Portfolio turnover: 11%
- Brokerage commissions: 0.00 bps of average net assets (SEC N-CEN)
MUB Cashflows
Over the 12 months to 2026-08, iShares National Muni Bond ETF had net inflows of $6,648,137,729, from monthly SEC N-PORT filings.
| Month | Net flow |
|---|---|
| 2026-08 | $306,423,503 |
| 2026-07 | $351,663,416 |
| 2026-06 | $654,728,134 |
| 2026-05 | $1,194,832,874 |
| 2026-04 | $768,130,124 |
| 2026-03 | $441,733,774 |
MUB Debt Constituents
Largest debt holdings of iShares National Muni Bond ETF by percentage of net assets, from the latest SEC N-PORT filing.
| Debt holding | % of net assets |
|---|---|
| Board of Regents of the University of Texas System | 0.18% |
| New York State Thruway Authority | 0.15% |
| New York State Dormitory Authority | 0.13% |
| Northwest Independent School District | 0.12% |
| Houston Higher Education Finance Corp. | 0.12% |
| State of New Jersey | 0.12% |
| Ohio State University (The) | 0.12% |
| State of Washington | 0.12% |
| State of California | 0.12% |
| Chicago Transit Authority Sales Tax Receipts Fund | 0.11% |
MUB Prospectus and SEC Filings
Official iShares National Muni Bond ETF filings on SEC EDGAR — prospectus, portfolio holdings and annual reports.
- Prospectus (485BPOS) — filed 2026-06-18
- Prospectus (485BPOS) — filed 2025-06-20
- Prospectus (485BPOS) — filed 2024-06-26
- Portfolio holdings (N-PORT) — filed 2026-10-22
- Portfolio holdings (N-PORT) — filed 2026-07-24
- Portfolio holdings (N-PORT) — filed 2026-04-22
- Annual census (N-CEN) — filed 2026-05-14
- Annual census (N-CEN) — filed 2025-05-14
MUB Service Providers
Firms that manage, distribute, hold, administer and audit iShares National Muni Bond ETF, as reported on SEC Form N-CEN, fiscal year ending February 28, 2026.
- Adviser: BlackRock Fund Advisors
- Distributor: BlackRock Investments, LLC
- Custodian: JPMorgan Chase Bank, N.A.
- Transfer agent: JPMorgan Chase Bank, N.A.
- Administrator: JPMorgan Chase Bank, N.A.
- Auditor: PricewaterhouseCoopers LLP
- Securities lending agent: BlackRock Institutional Trust Company, National Association
Related Funds
Other Intermediate Municipal Bond funds tracked on ABC INVEST:
MUB: Frequently Asked Questions
What is the expense ratio of iShares National Muni Bond ETF (MUB)?
MUB has a net expense ratio of 0.05%, about $5 a year for every $10,000 invested. MUB fees and costs
What index does MUB track?
MUB is an index fund that tracks the ICE AMT-Free US National Municipal Index.
What are MUB's top holdings?
As of August 31, 2026, MUB held 7,053 positions. The largest are Board of Regents of the University of Texas System (0.18%), San Antonio Water System (0.15%), New York State Thruway Authority (0.15%), New York State Dormitory Authority (0.13%) and Northwest Independent School District (0.12%). All MUB holdings
Can I download the full list of MUB holdings?
Yes. The complete MUB holdings list as of August 31, 2026 can be downloaded as a CSV file from the Holdings page: holding, ticker, FIGI, sector, country, asset type, shares, value and share of net assets, from the fund's SEC N-PORT filing. Download MUB holdings (CSV)
How has iShares National Muni Bond ETF performed?
MUB returned +3.9% over the 12 months to August 2026, +3.0% a year over 3 years and +0.6% a year over 5 years. MUB performance and risk
How large is MUB?
MUB manages $45,378,340,357 (SEC N-PORT, August 2026). Investors added a net $6,648,137,729 over the past 12 months.
Who manages MUB and when did it launch?
MUB is managed by BlackRock Fund Advisors. It is a series of iSHARES TRUST. It has traded on NYSE Arca since September 7, 2007.
How does MUB compare with similar Intermediate Municipal Bond funds?
Among 209 Intermediate Municipal Bond funds with $100,000,000+ in assets, MUB ranks #7 of 209 on net expense ratio (0.05%) and #2 of 209 by assets. The largest is Vanguard Intermediate-Term Tax-Exempt Fund (VWIUX). Compare MUB with VWIUX
Where can I find MUB's prospectus and SEC filings?
MUB's latest prospectus (485BPOS) was filed June 18, 2026 and its latest N-PORT holdings report was filed October 22, 2026. All 59 filings are linked on ABC INVEST and on SEC EDGAR (series S000018861). MUB SEC filings
What is the CUSIP and ISIN of MUB?
iShares National Muni Bond ETF (MUB) has CUSIP 464288414 and ISIN US4642884146. Brokers and trading platforms use these codes to look up the fund.
Data Sources
ABC INVEST compiles this page from public filings made to the U.S. Securities and Exchange Commission (SEC) through EDGAR: portfolio holdings and monthly cashflows from Form N-PORT, expenses and returns from fund prospectuses (Form 485BPOS) and the SEC DERA Risk/Return Summary data sets, and annual data from Form N-CEN.
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.