UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

(Amendment No. ________)*

PARTY CITY HOLDCO INC.

(Name of Issuer)

Common Stock, par value $0.01 per share

(Title of Class of Securities)

702149105

(CUSIP Number)

Richard Terranova, Advent International 75 State Street, Boston MA 02109

(Name, Address and Telephone Number of Person

Authorized to Receive Notices and Communications)

December 31, 2015

(Date of Event which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

¨  Rule 13d-1(b)

¨  Rule 13d-1(c)

x  Rule 13d-1(d)

^* The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

1.	NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Advent International Corporation
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 22,400,000
		6.	SHARED VOTING POWER 0
		7.	SOLE DISPOSITIVE POWER 22,400,000
		8.	SHARED DISPOSITIVE POWER 0
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 22,400,000
10.	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)  ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 18.8%
12.	TYPE OF REPORTING PERSON (see instructions) CO, IA

2

1.	NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Advent International LLC
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Massachusetts
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 22,400,000
		6.	SHARED VOTING POWER 0
		7.	SOLE DISPOSITIVE POWER 22,400,000
		8.	SHARED DISPOSITIVE POWER 0
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 22,400,000
10.	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)  ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 18.8%
12.	TYPE OF REPORTING PERSON (see instructions) OO

3

1.	NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Advent-PartyCity Acquisition Limited Partnership
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 22,400,000
		6.	SHARED VOTING POWER 0
		7.	SOLE DISPOSITIVE POWER 22,400,000
		8.	SHARED DISPOSITIVE POWER 0
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 22,400,000
10.	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)  ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 18.8%
12.	TYPE OF REPORTING PERSON (see instructions) PN

4

1.	NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Advent-PartyCity GP LLC
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 22,400,000
		6.	SHARED VOTING POWER 0
		7.	SOLE DISPOSITIVE POWER 22,400,000
		8.	SHARED DISPOSITIVE POWER 0
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 22,400,000
10.	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)  ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 17.3%
12.	TYPE OF REPORTING PERSON (see instructions) OO

5

1.	NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) GPE VI GP Limited Partnership
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Cayman Islands
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 19,788,160
		6.	SHARED VOTING POWER 0
		7.	SOLE DISPOSITIVE POWER 19,788,160
		8.	SHARED DISPOSITIVE POWER 0
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 19,788,160
10.	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)  ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 16.6%
12.	TYPE OF REPORTING PERSON (see instructions) PN

6

1.	NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) GPE VI GP (Delaware) Limited Partnership
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 2,166,080
		6.	SHARED VOTING POWER 0
		7.	SOLE DISPOSITIVE POWER 2,166,080
		8.	SHARED DISPOSITIVE POWER 0
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 2,166,080
10.	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)  ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 1.8%
12.	TYPE OF REPORTING PERSON (see instructions) PN

7

1.	NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Advent Partners GPE VI 2008 Limited Partnership
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 351,680
		6.	SHARED VOTING POWER 0
		7.	SOLE DISPOSITIVE POWER 351,680
		8.	SHARED DISPOSITIVE POWER 0
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 351,680
10.	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)  ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 0.3%
12.	TYPE OF REPORTING PERSON (see instructions) PN

8

1.	NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Advent Partners GPE VI 2009 Limited Partnership
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 11,200
		6.	SHARED VOTING POWER 0
		7.	SOLE DISPOSITIVE POWER 11,200
		8.	SHARED DISPOSITIVE POWER 0
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 11,200
10.	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)  ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 0.0%
12.	TYPE OF REPORTING PERSON (see instructions) PN

9

1.	NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Advent Partners GPE VI 2010 Limited Partnership
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 24,640
		6.	SHARED VOTING POWER 0
		7.	SOLE DISPOSITIVE POWER 24,640
		8.	SHARED DISPOSITIVE POWER 0
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 24,640
10.	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)  ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 0.0%
12.	TYPE OF REPORTING PERSON (see instructions) PN

10

1.	NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Advent Partners GPE VI-A 2010 Limited Partnership
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 31,360
		6.	SHARED VOTING POWER 0
		7.	SOLE DISPOSITIVE POWER 31,360
		8.	SHARED DISPOSITIVE POWER 0
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 31,360
10.	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)  ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 0.0%
12.	TYPE OF REPORTING PERSON (see instructions) PN

11

1.	NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Advent Partners GPE VI-A Limited Partnership
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 26,880
		6.	SHARED VOTING POWER 0
		7.	SOLE DISPOSITIVE POWER 26,880
		8.	SHARED DISPOSITIVE POWER 0
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 26,880
10.	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)  ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 0.0%
12.	TYPE OF REPORTING PERSON (see instructions) PN

12

1.	NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Advent International GPE VI Limited Partnership
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Cayman Islands
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 9,602,880
		6.	SHARED VOTING POWER 0
		7.	SOLE DISPOSITIVE POWER 9,602,880
		8.	SHARED DISPOSITIVE POWER 0
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 9,602,880
10.	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)  ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 8.1%
12.	TYPE OF REPORTING PERSON (see instructions) PN

13

1.	NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Advent International GPE VI-A Limited Partnership
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Cayman Islands
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 6,751,360
		6.	SHARED VOTING POWER 0
		7.	SOLE DISPOSITIVE POWER 6,751,360
		8.	SHARED DISPOSITIVE POWER 0
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 6,751,360
10.	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)  ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.7%
12.	TYPE OF REPORTING PERSON (see instructions) PN

14

1.	NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Advent International GPE VI-B Limited Partnership
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Cayman Islands
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 486,080
		6.	SHARED VOTING POWER 0
		7.	SOLE DISPOSITIVE POWER 486,080
		8.	SHARED DISPOSITIVE POWER 0
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 486,080
10.	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)  ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 0.4%
12.	TYPE OF REPORTING PERSON (see instructions) PN

15

1.	NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Advent International GPE VI-C Limited Partnership
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 495,040
		6.	SHARED VOTING POWER 0
		7.	SOLE DISPOSITIVE POWER 495,040
		8.	SHARED DISPOSITIVE POWER 0
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 495,040
10.	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)  ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 0.4%
12.	TYPE OF REPORTING PERSON (see instructions) PN

16

1.	NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Advent International GPE VI-D Limited Partnership
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 474,880
		6.	SHARED VOTING POWER 0
		7.	SOLE DISPOSITIVE POWER 474,880
		8.	SHARED DISPOSITIVE POWER 0
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 474,880
10.	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)  ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 0.4%
12.	TYPE OF REPORTING PERSON (see instructions) PN

17

1.	NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Advent International GPE VI-E Limited Partnership
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 1,196,160
		6.	SHARED VOTING POWER 0
		7.	SOLE DISPOSITIVE POWER 1,196,160
		8.	SHARED DISPOSITIVE POWER 0
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,196,160
10.	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)  ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 1.0%
12.	TYPE OF REPORTING PERSON (see instructions) PN

18

1.	NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Advent International GPE VI-F Limited Partnership
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Cayman Islands
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 1,807,680
		6.	SHARED VOTING POWER 0
		7.	SOLE DISPOSITIVE POWER 1,807,680
		8.	SHARED DISPOSITIVE POWER 0
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,807,680
10.	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)  ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 1.5%
12.	TYPE OF REPORTING PERSON (see instructions) PN

19

1.	NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Advent International GPE VI-G Limited Partnership
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Cayman Islands
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 1,140,160
		6.	SHARED VOTING POWER 0
		7.	SOLE DISPOSITIVE POWER 1,140,160
		8.	SHARED DISPOSITIVE POWER 0
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,140,160
10.	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)  ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 1.0%
12.	TYPE OF REPORTING PERSON (see instructions) PN

20

Item 1.

(a) Name of Issuer

Party City Holdco Inc.

(b) Address of Issuer’s Principal Executive Offices

80 Grasslands Road Elmsford, NY 10523 (914) 345-2020

Item 2.

(a) Name of Person Filing

(b) Address of Principal Business Office

(c) Citizenship

This statement is being filed on behalf of the following Reporting Persons:

Advent International Corporation, a Delaware corporation;

Advent International LLC, a Massachusetts LLC;

Advent-Party City Acquisition Limited Partnership, a Delaware limited partnership;

Advent-Party City GP LLC, a Delaware LLC;

GPE VI GP Limited Partnership, a Cayman Islands limited partnership

GPE VI GP (Delaware) Limited Partnership, a Delaware limited partnership;

Advent Partners GPE VI 2008 Limited Partnership, a Delaware limited partnership;

Advent Partners GPE VI 2009 Limited Partnership, a Delaware limited partnership;

Advent Partners GPE VI 2010 Limited Partnership, a Delaware limited partnership;

Advent Partners GPE VI-A 2010 Limited Partnership, a Delaware Islands limited partnership;

Advent Partners GPE VI-A Limited Partnership, a Delaware limited partnership;

Advent International GPE VI Limited Partnership, a Cayman Islands limited partnership;

Advent International GPE VI-A Limited Partnership, a Cayman Islands limited partnership;

Advent International GPE VI-B Limited Partnership, a Cayman Islands limited partnership;

Advent International GPE VI-C Limited Partnership, a Delaware limited partnership;

Advent International GPE VI-D Limited Partnership, a Delaware limited partnership;

Advent International GPE VI-E Limited Partnership, a Delaware limited partnership;

Advent International GPE VI-F Limited Partnership, a Cayman Islands limited partnership; and

Advent International GPE VI-G Limited Partnership, a Cayman Islands limited partnership.

Advent International Corporation is the manager of Advent International LLC, which in turn is the general partner of GPE VI GP Limited Partnership, GPE VI GP (Delaware) Limited Partnership, Advent Partners GPE VI 2008 Limited Partnership, Advent Partners GPE VI 2009 Limited Partnership, Advent Partners GPE VI 2010 Limited Partnership, Advent Partners GPE VI-A 2010 Limited Partnership, and Advent Partners GPE VI-A Limited Partnership. GPE VI GP Limited Partnership is the general partner of Advent International GPE VI Limited Partnership, Advent International GPE VI-A Limited Partnership, Advent International GPE VI-B Limited Partnership, Advent International GPE VI-F Limited Partnership and Advent International GPE VI-G Limited Partnership. GPE VI GP (Delaware) Limited Partnership is the general partner of Advent International GPE VI-C Limited Partnership, Advent International GPE VI-D Limited Partnership and Advent International GPE VI-E Limited Partnership. Advent-Party City GP LLC is a general partner of Advent-Party City Acquisition Limited Partnership. Advent Partners GPE VI 2008 Limited Partnership, Advent Partners GPE VI

21

2009 Limited Partnership, Advent Partners GPE VI 2010 Limited Partnership, Advent Partners GPE VI-A 2010 Limited Partnership, Advent Partners GPE VI-A Limited Partnership, Advent International GPE VI Limited Partnership, Advent International GPE VI-A Limited Partnership, Advent International GPE VI-B Limited Partnership, Advent International GPE VI-G Limited Partnership Advent International GPE VI-C Limited Partnership, Advent International GPE VI-D Limited Partnership and Advent International GPE VI-E Limited Partnership are members of Advent-Party City GP LLC.

The principal business address of each Reporting Person is c/o Advent International Corporation, 75 State Street, Boston, MA 02109.

(d) Title of Class of Securities

Common stock, par value $0.01 per share

(e) CUSIP Number

702149105

Item 3. If this statement is filed pursuant to §§240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

Not applicable

Item 4. Ownership.

Provide the following information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1.

	Number of Shares Beneficially Owned		Sole Voting Power		Shared Voting Power		Sole Dispositive Power		Shared Dispositive Power		Percentage of Common Stock Outstanding
Advent International Corporation		22,400,000		22,400,000		—		22,400,000		—		18.8	%
Advent International LLC		22,400,000		22,400,000		—		22,400,000		—		18.8	%
Advent-Party Cith Acquisition Limited Partnership		22,400,000		22,400,000		—		22,400,000		—		18.8	%
Advent-Party City GP LLC		22,400,000		22,400,000		—		22,400,000		—		18.8	%
GPE VI GP Limited Partnership		19,788,160		19,788,160		—		19,788,160		—		16.6	%
GPE VI GP (Delaware) Limited Partnership		2,166,080		2,166,080		—		2,166,080		—		1.8	%
Advent Partners GPE VI 2008 Limited Partnership		351,680		351,680		—		351,680		—		0.3	%
Advent Partners GPE VI 2009 Limited Partnership		11,200		11,200		—		11,200		—		0.0	%
Advent Partners GPE VI 2010 Limited Partnership		24,640		24,640		—		24,640		—		0.0	%
Advent Partners GPE VI-A 2010 Limited Partnership		31,360		31,360		—		31,360		—		0.0	%
Advent Partners GPE VI-A Limited Partnership		26,880		26,880		—		26,880		—		0.0	%
Advent International GPE VI Limited Partnership		9,602,880		9,602,880		—		9,602,880		—		8.1	%
Advent International GPE VI-A Limited Partnership		6,751,360		6,751,360		—		6,751,360		—		5.7	%
Advent International GPE VI-B Limited Partnership		486,080		486,080		—		486,080		—		0.4	%
Advent International GPE VI-C Limited Partnership		495,040		495,040		—		495,040		—		0.4	%
Advent International GPE VI-D Limited Partnership		474,880		474,880		—		474,880		—		0.4	%
Advent International GPE VI-E Limited Partnership		1,196,160		1,196,160		—		1,196,160		—		1.0	%
Advent International GPE VI-F Limited Partnership		1,807,680		1,807,680		—		1,807,680		—		1.5	%
Advent International GPE VI-G Limited Partnership		1,140,160		1,140,160		—		1,140,160		—		1.0	%

Item 5. Ownership of Five Percent or Less of a Class.

Not applicable

22

Item 6. Ownership of More than Five Percent on Behalf of Another Person.

Not applicable

Item 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company. 

Not applicable

Item 8. Identification and Classification of Members of the Group

See Exhibit 2.

Item 9. Notice of Dissolution of Group

Not Applicable

Item 10. Certification

Not Applicable

23

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

February 12, 2016

Date

Advent International GPE VI Limited Partnership

Advent International GPE VI-A Limited Partnership

Advent International GPE VI-B Limited Partnership

Advent International GPE VI-F Limited Partnership

Advent International GPE VI-G Limited Partnership

By: GPE VI GP Limited Partnership, General Partner

By: Advent International LLC, General Partner

By: Advent International Corporation, Manager

By: Richard Terranova, Authorized Signatory

/s/ Richard Terranova

Signature

Advent International GPE VI-C Limited Partnership

Advent International GPE VI-D Limited Partnership

Advent International GPE VI-E Limited Partnership

By: GPE VI GP (Delaware) Limited Partnership, General Partner

By: Advent International LLC, General Partner

By: Advent International Corporation, Manager

By: Richard Terranova, Authorized Signatory

/s/ Richard Terranova

Signature

Advent Partners GPE VI 2008 Limited Partnership

Advent Partners GPE VI 2009 Limited Partnership

Advent Partners GPE VI 2010 Limited Partnership

Advent Partners GPE VI-A Limited Partnership

Advent Partners GPE VI-A 2010 Limited Partnership

By: Advent International LLC, General Partner

By: Advent International Corporation, Manager

By: Richard Terranova, Authorized Signatory

/s/ Richard Terranova

Signature

GPE VI GP Limited Partnership

By: Advent International LLC, General Partner

By: Advent International Corporation, Manager

By: Richard Terranova, Authorized Signatory

/s/ Richard Terranova

Signature

24

GPE VI GP (Delaware) Limited Partnership

By: Advent International LLC, General Partner

By: Advent International Corporation, Manager

By: Richard Terranova, Authorized Signatory

/s/ Richard Terranova

Signature

Advent International LLC

By: Advent International Corporation, Manager

By: Richard Terranova, Authorized Signatory

/s/ Richard Terranova

Signature

Advent International Corporation

By: Richard Terranova, Authorized Signatory

/s/ Richard Terranova

Signature

Advent-Party City Acquisition Limited Partnership

By: Advent-Party City GP LLC, General Partner

By: Richard Terranova, Authorized Signatory

/s/ Richard Terranova

Signature

Advent-Party City GP LLC

By: Richard Terranova, Authorized Signatory

/s/ Richard Terranova

Signature

25

EXHIBIT INDEX

Exhibit 1.	Joint Filing Agreement as required by Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended.
Exhibit 2.	List of Members of a Group

26

Exhibit 1

JOINT FILING AGREEMENT PURSUANT TO RULE 13d-1(k)(1)

The undersigned acknowledge and agree that the foregoing statement on Schedule 13G is filed on behalf of each of the undersigned and that all subsequent amendments to this statement on Schedule 13G shall be filed on behalf of each of the undersigned without the necessity of filing additional joint filing statements. The undersigned acknowledge that each shall be responsible for the timely filing of such amendments, and for the completeness and accuracy of the information concerning him, her or it contained herein, but shall not be responsible for the completeness and accuracy of the information concerning the other entities or persons, except to the extent that he, she or it knows or has reason to believe that such information is inaccurate.

February 12, 2016

Date

Advent International GPE VI Limited Partnership

Advent International GPE VI-A Limited Partnership

Advent International GPE VI-B Limited Partnership

Advent International GPE VI-F Limited Partnership

Advent International GPE VI-G Limited Partnership

By: GPE VI GP Limited Partnership, General Partner

By: Advent International LLC, General Partner

By: Advent International Corporation, Manager

By: Richard Terranova, Authorized Signatory

/s/ Richard Terranova

Signature

Advent International GPE VI-C Limited Partnership

Advent International GPE VI-D Limited Partnership

Advent International GPE VI-E Limited Partnership

By: GPE VI GP (Delaware) Limited Partnership, General Partner

By: Advent International LLC, General Partner

By: Advent International Corporation, Manager

By: Richard Terranova, Authorized Signatory

/s/ Richard Terranova

Signature

Advent Partners GPE VI 2008 Limited Partnership

Advent Partners GPE VI 2009 Limited Partnership

Advent Partners GPE VI 2010 Limited Partnership

Advent Partners GPE VI-A Limited Partnership

Advent Partners GPE VI-A 2010 Limited Partnership

By: Advent International LLC, General Partner

By: Advent International Corporation, Manager

By: Richard Terranova, Authorized Signatory

/s/ Richard Terranova

Signature

GPE VI GP Limited Partnership

By: Advent International LLC, General Partner

By: Advent International Corporation, Manager

By: Richard Terranova, Authorized Signatory

/s/ Richard Terranova

Signature

27

GPE VI GP (Delaware) Limited Partnership

By: Advent International LLC, General Partner

By: Advent International Corporation, Manager

By: Richard Terranova, Authorized Signatory

/s/ Richard Terranova

Signature

Advent International LLC

By: Advent International Corporation, Manager

By: Richard Terranova, Authorized Signatory

/s/ Richard Terranova

Signature

Advent International Corporation

By: Richard Terranova, Authorized Signatory

/s/ Richard Terranova

Signature

Advent-Party City Acquisition Limited Partnership

By: Advent-Party City GP LLC, General Partner

By: Richard Terranova, Authorized Signatory

/s/ Richard Terranova

Signature

Advent-Party City GP LLC

By: Richard Terranova, Authorized Signatory

/s/ Richard Terranova

Signature

28

Exhibit 2

MEMBERS OF A GROUP

Advent International Corporation

Advent International LLC

Advent-Party City Acquisition Limited Partnership

Advent-Party City GP LLC

GPE VI GP Limited Partnership

GPE VI GP (Delaware) Limited Partnership

Advent Partners GPE VI 2008 Limited Partnership

Advent Partners GPE VI 2009 Limited Partnership

Advent Partners GPE VI 2010 Limited Partnership

Advent Partners GPE VI-A 2010 Limited Partnership

Advent Partners GPE VI-A Limited Partnership

Advent International GPE VI Limited Partnership

Advent International GPE VI-A Limited Partnership

Advent International GPE VI-B Limited Partnership

Advent International GPE VI-C Limited Partnership

Advent International GPE VI-D Limited Partnership

Advent International GPE VI-E Limited Partnership

Advent International GPE VI-F Limited Partnership

Advent International GPE VI-G Limited Partnership

29