Ownership Submission
FORM 3
 UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

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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(Print or Type Responses)
1. Name and Address of Reporting Person *
  M/C VENTURE PARTNERS VI L P
 2. Date of Event Requiring Statement (Month/Day/Year)
10/16/2014		 3. Issuer Name and Ticker or Trading Symbol
Zayo Group Holdings, Inc. [ZAYO]
(Last)
(First)
(Middle)
C/O M/C PARTNERS, 75 STATE STREET, SUITE 2500		 4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director __X__ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
5. If Amendment, Date Original Filed(Month/Day/Year)
10/16/2014
(Street)

BOSTON, MA 02109		 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 Beneficially Owned
1.Title of Security
(Instr. 4)		 2. Amount of Securities Beneficially Owned
(Instr. 4)		 3. Ownership Form: Direct (D) or Indirect (I)
(Instr. 5)		 4. Nature of Indirect Beneficial Ownership
(Instr. 5)
Common Stock 25,437,645
I
See Footnotes (1) (2)
Common Stock 174,870
I
See Footnotes (3) (4)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 4)		 2. Date Exercisable and Expiration Date
(Month/Day/Year)		 3. Title and Amount of Securities Underlying Derivative Security
(Instr. 4)		 4. Conversion or Exercise Price of Derivative Security 5. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 5)		 6. Nature of Indirect Beneficial Ownership
(Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
M/C VENTURE PARTNERS VI L P
C/O M/C PARTNERS
75 STATE STREET, SUITE 2500
BOSTON, MA 02109		     X    
M/C Venture Investors LLC
C/O M/C PARTNERS
75 STATE STREET, SUITE 2500
BOSTON, MA 02109		     X    
M/C Venture Partners V, L.P.
C/O M/C PARTNERS
75 STATE STREET, SUITE 2500
BOSTON, MA 02109		     X    
Chestnut Venture Partners LP
C/O M/C PARTNERS
75 STATE STREET, SUITE 2500
BOSTON, MA 02109		     X    
M/C VP VI, L.P.
C/O M/C PARTNERS
75 STATE STREET, SUITE 2500
BOSTON, MA 02109		     X    
M/C Venture Partners, LLC
C/O M/C PARTNERS
75 STATE STREET, SUITE 2500
BOSTON, MA 02109		     X    
M/C VP V, LLC
C/O M/C PARTNERS
75 STATE STREET, SUITE 2500
BOSTON, MA 02109		     X    
Chestnut Street Partners Inc
C/O M/C PARTNERS
75 STATE STREET, SUITE 2500
BOSTON, MA 02109		     X    
Corelink Data Centers, LLC
C/O M/C PARTNERS
75 STATE STREET, SUITE 2500
BOSTON, MA 02109		     X    

Signatures

M/C VENTURE PARTNERS VI, L.P., By: M/C VP VI, L.P., its general partner, By: M/C Venture Partners, LLC, its general partner, By: /s/ Gillis S. Cashman, Manager 02/10/2015
**Signature of Reporting Person Date
M/C VENTURE INVESTORS L.L.C., By: /s/ Gillis S. Cashman, Manager 02/10/2015
**Signature of Reporting Person Date
M/C VENTURE PARTNERS V, L.P., By: M/C VP V LLC, its general partner, By: /s/ Gillis S. Cashman, Manager 02/10/2015
**Signature of Reporting Person Date
CHESTNUT VENTURE PARTNERS, L.P., By: Chestnut Street Partners, Inc., its general partner, By: /s/ David D. Croll, President 02/10/2015
**Signature of Reporting Person Date
M/C VP VI, L.P., By: M/C Venture Partners, LLC, its general partner, By: /s/ Gillis S. Cashman, Manager 02/10/2015
**Signature of Reporting Person Date
M/C VENTURE PARTNERS, LLC, By: /s/ Gillis S. Cashman, Manager 02/10/2015
**Signature of Reporting Person Date
M/C VP V LLC, By: /s/ Gillis S. Cashman, Manager 02/10/2015
**Signature of Reporting Person Date
CHESTNUT STREET PARTNERS, INC., By: /s/ David D. Croll, President 02/10/2015
**Signature of Reporting Person Date
CORELINK DATA CENTERS, LLC, By: M/C Venture Partners VI, L.P., its managing member, By: M/C VP VI, L.P., its general partner, By: M/C Venture Partners, LLC, its general partner, By: /s/ Gillis S. Cashman, Manager 02/10/2015
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 5(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).
(1) Consists of (i) 24,160,854 shares held of record by M/C Venture Partners VI, L.P.; (ii) 757,871 shares held of record by M/C Venture Investors L.L.C.; (iii) 497,320 shares held of record by M/C Venture Partners V, L.P.; and (iv) 21,600 shares held of record by Chestnut Venture Partners, L.P. (together, the "M/C Shareholders"). M/C VP VI, L.P. is the sole general partner of M/C Venture Partners VI, L.P. and M/C Venture Partners, LLC is the sole general partner of M/C VP VI, L.P. M/C VP V LLC is the sole general partner of M/C Venture Partners V, L.P. (continued)
(2) (continued from footnote 1) Chestnut Street Partners, Inc. is the sole general partner of Chestnut Venture Partners, L.P. As the Managers of M/C Venture Partners, LLC, M/C Venture Investors L.L.C. and M/C VP V LLC, Gillis S. Cashman, Brian M. Clark, David D. Croll, James F. Wade and John W. Watkins collectively have direct or indirect investment and voting authority over the securities held by M/C Venture Partners VI, L.P., M/C Venture Investors L.L.C. and M/C Venture Partners V, L.P. David D. Croll and James F. Wade collectively have investment and voting authority over the securities held by Chestnut Venture Partners, L.P. Each of the foregoing entities and individuals disclaims beneficial ownership of the shares held of record by the M/C Shareholders, except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that the reporting person is the beneficial owner of the securities for purposes of Section 16 or for any other purpose.
(3) The original Form 3 filed by M/C Venture Partners VI, L.P., M/C Venture Partners, LLC, M/C VP VI, L.P., M/C Venture Investors L.L.C., M/C Venture Partners V, L.P., M/C VP V LLC, Chestnut Venture Partners, L.P and Chestnut Street Partners, Inc. inadvertently omitted holdings by Corelink Data Centers, LLC. M/C Venture Partners VI, L.P., M/C VP VI, L.P. and M/C Venture Partners, LLC may be deemed to share beneficial ownership with respect to the shares held by Corelink Data Centers, LLC. M/C Venture Partners VI, L.P. is the managing member of Corelink Data Centers, LLC. M/C VP VI, L.P. is the sole general partner of M/C Venture Partners VI, L.P. and M/C Venture Partners, LLC is the sole general partner of M/C VP VI, L.P. (continued)
(4) (continued from footnote 3) As the Managers of M/C Venture Partners, LLC, Gillis S. Cashman, Brian M. Clark, David D. Croll, James F. Wade and John W. Watkins collectively have direct or indirect investment and voting authority over the securities held by Corelink Data Centers, LLC. Each of the foregoing entities and individuals disclaims beneficial ownership of the shares held of record by Corelink Data Centers, LLC.

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