Sec Form 4 Filing - CAVANAGH RICHARD @ BLACKROCK MUNIASSETS FUND, INC. - 2011-02-28

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person CAVANAGH RICHARD 2. Issuer Name and Ticker or Trading Symbol BLACKROCK MUNIASSETS FUND, INC. [ MUA] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 55 EAST 52ND STREET 3. Date of Earliest Transaction (MM/DD/YY) 02/28/2011 (Street) NEW YORK, NY10055 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 02/28/2011 A 72 A 172 D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other CAVANAGH RICHARD 55 EAST 52ND STREET NEW YORK, NY10055 X Signatures /s/ Aaron Wasserman as Attorney-in-Fact 03/02/2011 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Effective as of February 28, 2011, BlackRock Apex Municipal Fund, Inc. (the "Target Fund") merged into the Issuer (the "Reorganization"). In the Reorganization, common stockholders of the Target Fund received shares of common stock of the Issuer in an amount equal to the aggregate net asset value of the Target Fund's common stock as determined at the close of business on February 25, 2011, less the costs of the Reorganization (although cash was distributed for any fractional shares of common stock). As of February 25, 2011, the Target Fund reported a net asset value per share of $8.8277 and the Issuer reported a net asset value per share of $12.1158. The conversion ratio for the Target Fund's shares of common stock was 0.72861057. In the Reorganization, Mr. Cavanagh received 72 shares of common stock of the Issuer in exchange for his 100 shares of common stock of the Target Fund.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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