# EDGAR Filing Document

**Accession Number:** 0000225635
**File Stem:** 0001193125-25-203932
**Filing Date:** 2025-9
**Character Count:** 6209
**Document Hash:** 7b5e44fefd268321f23455951d1fac9b
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-25-203932.hdr.sgml**: 20250916

**ACCESSION NUMBER**: 0001193125-25-203932

**CONFORMED SUBMISSION TYPE**: 497K

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20250916

**DATE AS OF CHANGE**: 20250915

**EFFECTIVENESS DATE**: 20250916

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** BLACKROCK MUNICIPAL BOND FUND, INC.
- **CENTRAL INDEX KEY:** 0000225635

**ORGANIZATION NAME:**
- **EIN:** 132896246
- **STATE OF INCORPORATION:** NJ
- **FISCAL YEAR END:** 0630

**FILING VALUES:**
- **FORM TYPE:** 497K
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 002-57354
- **FILM NUMBER:** 251315398

**BUSINESS ADDRESS:**
- **STREET 1:** 100 BELLEVUE PARKWAY
- **CITY:** WILMINGTON
- **STATE:** DE
- **ZIP:** 19809
- **BUSINESS PHONE:** 800-441-7762

**MAIL ADDRESS:**
- **STREET 1:** 100 BELLEVUE PARKWAY
- **CITY:** WILMINGTON
- **STATE:** DE
- **ZIP:** 19809

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** MERRILL LYNCH MUNICIPAL BOND FUND INC
- **DATE OF NAME CHANGE:** 19920703

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** ONE LIBERTY MUNICIPAL BOND FUND INC
- **DATE OF NAME CHANGE:** 19780622

## Series and Classes Contracts Data

### BlackRock National Municipal Fund (Series ID: S000002334)

| Class ID   | Class Name     | Ticker Symbol   |
|:---|:---|:---|
| C000006118 | Investor A     |  |
| C000006121 | Institutional  |  |
| C000038033 | Investor C     |  |
| C000100249 | Service Shares |  |
| C000100250 | Class K        |  |

**BLACKROCK MUNICIPAL BOND FUND, INC.** 

**BlackRock National Municipal Fund** 

(the "Fund")

**Supplement dated September 16, 2025 (the "Supplement") to the Fund's** 

**Summary Prospectuses and Prospectuses, each dated October 28, 2024, as supplemented to date** 

**The following changes are made to the Fund's Summary Prospectuses and Prospectuses, as applicable:** 

**The section of the Summary Prospectuses entitled "Key Facts About BlackRock National Municipal Fund — Portfolio Managers" and the section of the Prospectuses entitled "Fund Overview — Key Facts About BlackRock National Municipal Fund — Portfolio Managers" are deleted in their entirety and replaced with the following:** 

***Portfolio Managers***

---

| | | |
|:---|:---|:---|
| **Portfolio Managers** | **Portfolio Manager of<br>the Fund Since** | **Title** |
| Walter O'Conner, CFA<sup>1</sup> | 1996 | Managing Director of BlackRock, Inc. |
| Michael Kalinoski, CFA | 2016 | Director of BlackRock, Inc. |
| Kevin Maloney, CFA | 2022 | Managing Director of BlackRock, Inc. |
| Phillip Soccio, CFA | 2022 | Director of BlackRock, Inc. |
| Sean Carney | 2025 | Managing Director of BlackRock, Inc. |

---

<sup>1</sup> On or about March 17, 2026, Walter O'Connor, CFA, will no longer serve as a portfolio manager of the Fund.

**The section of the Prospectuses for Investor A Shares, Investor C Shares, Institutional Shares and Class K Shares entitled "Details About the Funds — How Each Fund Invests — National Fund — About the Portfolio Management of the National Fund" and the section of the Prospectus for Service Shares "Details About the Fund — How the Fund Invests — About the Portfolio Management of the Fund" are deleted in their entirety and replaced with the following:** 

---

| |
|:---|
| &nbsp;&nbsp;&nbsp;**ABOUT THE PORTFOLIO MANAGEMENT OF THE NATIONAL FUND** |
| &nbsp;&nbsp;&nbsp;The Fund is managed by a team of financial professionals. Walter O'Conner, CFA,<sup>1</sup> Michael Kalinoski, CFA, Kevin Maloney, CFA, Phillip Soccio, CFA, and Sean Carney are the portfolio managers and are jointly and primarily responsible for the day-to-day management of the Fund. Please see "Management of the Funds — Portfolio Manager Information" for additional information about the portfolio management team. |

---

<sup>1</sup> On or about March 17, 2026, Walter O'Connor, CFA, will no longer serve as a portfolio manager of the Fund.

**The section of the Prospectuses for Investor A Shares, Investor C Shares, Institutional Shares and Class K Shares entitled "Management of the Funds — Portfolio Manager Information — National Fund" and the section of the Prospectus for Service Shares "Management of the Fund — Portfolio Manager Information" are deleted in their entirety and replaced with the following:** 

**National Fund** 

The Fund is managed by a team of financial professionals. Walter O'Connor, CFA, Michael Kalinoski, CFA, Kevin Maloney, CFA, and Phillip Soccio, CFA, are jointly and primarily responsible for the day-to-day management of the Fund.

------

---

| | | | |
|:---|:---|:---|:---|
| **Portfolio Manager** | **Primary Role** | **Since** | **Title and Recent Biography** |
| Walter O'Conner, CFA | Responsible for the day-to-day management of the Fund's portfolio, including setting the Fund's overall investment strategy and overseeing the management of the Fund. | 1996 | Managing Director of BlackRock, Inc. since 2006. |
| Michael Kalinoski, CFA | Responsible for the day-to-day management of the Fund's portfolio, including setting the Fund's overall investment strategy and overseeing the management of the Fund. | 2016 | Director of BlackRock, Inc. since 2006. |
| Kevin Maloney, CFA | Responsible for the day-to-day management of the Fund's portfolio, including setting the Fund's overall investment strategy and overseeing the management of the Fund. | 2022 | Managing Director of BlackRock since 2025; Director of BlackRock from 2021 to 2024; Vice President of BlackRock, Inc. from 2018 to 2020. |
| Phillip Soccio, CFA | Responsible for the day-to-day management of the Fund's portfolio, including setting the Fund's overall investment strategy and overseeing the management of the Fund. | 2022 | Director of BlackRock, Inc. since 2009. |
| Sean Carney | Responsible for the day-to-day management of the Fund's portfolio, including setting the Fund's overall investment strategy and overseeing the management of the Fund. | 2025 | Managing Director of BlackRock, Inc. since 2018. |

---

<sup>1</sup> On or about March 17, 2026, Walter O'Connor, CFA, will no longer serve as a portfolio manager of the Fund.

**Shareholders should retain this Supplement for future reference.**