SEC Form 4

FORM 4		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 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
X	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* CHARLES RIVER PARTNERSHIP XI LP (Last) (First) (Middle) 1000 WINTER STREET SUITE 3300 (Street) WALTHAM MA 02451 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol BigBand Networks, Inc. [ BBND ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 12/21/2009
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	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	12/21/2009		J(1)		1,889,274(2)	D	$0	5,454,099(3)	I	See Footnotes(4)(5)

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 (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	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 (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (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: 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

1. Name and Address of Reporting Person* CHARLES RIVER PARTNERSHIP XI LP (Last) (First) (Middle) 1000 WINTER STREET SUITE 3300 (Street) WALTHAM MA 02451 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Charles River XI GP, LP (Last) (First) (Middle) 1000 WINTER STREET SUITE 3300 (Street) WALTHAM MA 02451 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Charles River XI GP, LLC (Last) (First) (Middle) 1000 WINTER STREET SUITE 3300 (Street) WALTHAM MA 02451 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

1. Pro rata distribution for no consideration to partners of the limited partnership.

2. These securities are owned by Charles River Partnership XI, LP ("CRP XI"), which is a member of a "group" with Charles River Friends XI-A, LP and Charles River Friends XI-B, LP for purposes of Section 13(d) of the Exchange Act. Charles River XI GP, LP ("CR XI GP LP") is the General Partner of CRP XI. Charles River XI GP, LLC ("CR XI GP LLC") is in turn the General Partner of CR XI GP LP.

3. CRP XI and its affiliated entities hold an aggregate of 6,212,558, which consists of 5,454,099 shares held by CRP XI, 191,346 shares held by Charles River Friends XI-A, LP, 37,820 shares held by Charles River Friends XI-B, LP, and 529,293 shares held by CR XI GP LP.

4. Held by CRP XI and its affiliated funds as a group for purposes of Section 13(d) of the Exchange Act. Each of Izhar Armony, Christopher Baldwin, Richard M. Burnes, Jr., Ted R. Dintersmith, Bruce I. Sachs, William P. Tai and Michael J. Zak is a managing member of CR XI GP LLC. Accordingly, each of CR XI GP, LP, CR XI GP LLC and Messrs. Armony, Baldwin, Burnes, Dintersmith, Sachs, Tai and Zak (collectively, the "Management Persons") may be deemed to beneficially own the securities owned by the Partnerships. Each of the Management Persons disclaims beneficial ownership of the securities reported herein held by the Partnership, except to the extent of such person's pecuniary interest in each applicable Partnership, if any.

5. 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 Exchange Act or otherwise, the beneficial owner of any equity securities. Each pro rata distribution from the Partnerships to the Management Persons, and from one Management Person to another Management Person as general partner or member of the distributing Management Person, reflects a change in form of beneficial ownership only of the ultimate Management Persons, and does not reflect a change in such ultimate Management Persons' pecuniary interest in the securities reported herein.

	Sarah Reed, as Attorney-in-Fact for Charles River XI GP, LLC, the General Partner of Charles River XI GP, LP, which is the General Partner of Charles River Partnership XI, LP	12/23/2009
	Sarah Reed, as Attorney-in-Fact for Charles River XI GP, LLC, the General Partner of Charles River XI GP, LP	12/23/2009
	Sarah Reed, as Attorney-in-Fact for Charles River XI GP, LLC	12/23/2009
	** Signature of Reporting Person	Date
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* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
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