Sec Form 4 Filing - Charles River Partnership XIII, LP @ Millennial Media Inc. - 2013-03-05

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 Charles River Partnership XIII, LP 2. Issuer Name and Ticker or Trading Symbol Millennial Media Inc. [ MM] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) ONE BROADWAY, 15TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 03/05/2013 (Street) CAMBRIDGE, MA02142 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ 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 03/05/2013 J( 1 ) 500,000 ( 1 ) D $ 0 8,172,214 ( 2 ) D ( 3 ) ( 4 ) Common Stock 03/06/2013 S( 5 ) 14,034 D $ 8.1913 8,158,180 ( 6 ) D ( 4 )

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 Charles River Partnership XIII, LP ONE BROADWAY 15TH FLOOR CAMBRIDGE, MA02142 X Charles River Friends XIII-A LP ONE BROADWAY 15TH FLOOR CAMBRIDGE, MA02142 X Charles River XIII GP, LP ONE BROADWAY 15TH FLOOR CAMBRIDGE, MA02142 X Charles River XIII GP, LLC ONE BROADWAY 15TH FLOOR CAMBRIDGE, MA02142 X Signatures /s/ Sarah Reed, as Attorney-in-Fact for Charles River Partnership XIII, LP 03/07/2013 Signature of Reporting Person Date /s/ Sarah Reed, as Attorney-in-Fact for Charles River Friends XIII-A, LP 03/07/2013 Signature of Reporting Person Date /s/ Sarah Reed, as Attorney-in-Fact for Charles River XIII GP, LP 03/07/2013 Signature of Reporting Person Date /s/ Sarah Reed, as Attorney-in-Fact for Charles River XIII GP, LLC 03/07/2013 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents a pro rata distribution for no consideration to the partners of Charles River Partnership XIII, LP ("CRP XIII LP"). Of the 500,000 shares distributed, 8,021 shares were distributed to Charles River XIII GP, LP ("CR XIII GP LP"), which is the general partner of CRP XIII LP, and these shares were then further distributed on a pro rata basis for no consideration to the partners of CR XIII GP LP. Of the 8,021 shares distributed by CR XIII GP LP, 9 shares were received by Charles River XIII GP, LLC ("CR XIII GP LLC") which is the general partner of CR XIII GP, LP. CR XIII GP LLC then distributed these 9 shares on a pro rata basis for no consideration to its members. ( 2 )The number of shares owned after the distribution includes 7,935,447 shares held by CRP XIII LP and 236,767 shares held by Charles River Friends XIII-A, LP ("CRF XIII-A"). ( 3 )The pro rata distribution from CRP XIII LP to its partners, and from one partner to another partner as general partner or member of the distributing partner, reflects a change in form of beneficial ownership only of the ultimate partner, and does not reflect a change in such ultimate partner's pecuniary interest in the securities reported herein. ( 4 )CR XIII GP LP is the general partner of CRP XIII LP. CR XIII GP LLC is the general partner of both CRF XIII-A and CR XIII GP, LP. Each reporting person may be deemed to beneficially own the reported securities, but each disclaims beneficial ownership of such reported securities except to the extent of its pecuniary interest therein. The filing of this statement by any reporting person shall not be deemed an admission that such person is, for purposes of Section 16 of the Securities Exchange Act of 1934 or otherwise, the beneficial owner of any equity securities covered by this statement. ( 5 )Sale by CRF XIII-A. ( 6 )The number of shares owned after the sale includes 7,935,447 shares held by CRP XIII LP and 222,733 shares held by CRF XIII-A.

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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