UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

(Amendment No. 1)*

PARTY CITY HOLDCO INC.

(Name of Issuer)

COMMON STOCK, PAR VALUE $0.01 PER SHARE

(Title of Class of Securities)

702149105

(CUSIP Number)

December 31, 2017

(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)

☒

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 the disclosures provided in a prior cover page.

The information required in 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).

CUSIP NO. 702149105

13G

PAGE 2 OF 28

1	NAME OF REPORTING PERSON
	Thomas H. Lee Advisors, LLC

2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
	(a)☐
	(b)☒
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
			-0-

		6	SHARED VOTING POWER
			57,716,258

		7	SOLE DISPOSITIVE POWER
			-0-

		8	SHARED DISPOSITIVE POWER
			57,716,258

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
	57,716,258

10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*


11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
	59.88% (1)

12	TYPE OF REPORTING PERSON*
	OO

(1)

The calculation of the foregoing percentage is based on 96,380,102 shares of Common Stock outstanding as of December 31, 2017, as provided by the Issuer.

CUSIP NO. 702149105

13G

PAGE 3 OF 28

1	NAME OF REPORTING PERSON
	THL PC Topco, L.P.

2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
	(a)☐
	(b)☒
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
			-0-

		6	SHARED VOTING POWER
			57,716,258

		7	SOLE DISPOSITIVE POWER
			-0-

		8	SHARED DISPOSITIVE POWER
			57,716,258

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
	57,716,258

10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*


11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
	59.88% (1)

12	TYPE OF REPORTING PERSON*
	PN

*SEE INSTRUCTIONS BEFORE FILLING OUT

(1)

The calculation of the foregoing percentage is based on 96,380,102 shares of Common Stock outstanding as of December 31, 2017, as provided by the Issuer.

CUSIP NO. 702149105

13G

PAGE 4 OF 28

1	NAME OF REPORTING PERSON
	Thomas H. Lee Equity Fund VI, L.P.

2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
	(a)☐
	(b)☒
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
			-0-

		6	SHARED VOTING POWER
			24,640,697

		7	SOLE DISPOSITIVE POWER
			-0-

		8	SHARED DISPOSITIVE POWER
			24,640,697

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
	24,640,697

10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*


11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
	25.57% (1)

12	TYPE OF REPORTING PERSON*
	PN

*SEE INSTRUCTIONS BEFORE FILLING OUT

(1)

The calculation of the foregoing percentage is based on 96,380,102 shares of Common Stock outstanding as of December 31, 2017, as provided by the Issuer.

CUSIP NO. 702149105

13G

PAGE 5 OF 28

1	NAME OF REPORTING PERSON
	Thomas H. Lee Parallel Fund VI, L.P.

2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
	(a)☐
	(b)☒
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
			-0-

		6	SHARED VOTING POWER
			16,685,370

		7	SOLE DISPOSITIVE POWER
			-0-

		8	SHARED DISPOSITIVE POWER
			16,685,370

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
	16,685,370

10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*


11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
	17.31% (1)

12	TYPE OF REPORTING PERSON*
	PN

*SEE INSTRUCTIONS BEFORE FILLING OUT

(1)

The calculation of the foregoing percentage is based on 96,380,102 shares of Common Stock outstanding as of December 31, 2017, as provided by the Issuer.

CUSIP NO. 702149105

13G

PAGE 6 OF 28

1	NAME OF REPORTING PERSON
	Thomas H. Lee Parallel (DT) Fund VI, L.P.

2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
	(a)☐
	(b)☒
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
			-0-

		6	SHARED VOTING POWER
			2,914,599

		7	SOLE DISPOSITIVE POWER
			-0-

		8	SHARED DISPOSITIVE POWER
			2,914,599

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
	2,914,599

10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*


11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
	3.02% (1)

12	TYPE OF REPORTING PERSON*
	PN

*SEE INSTRUCTIONS BEFORE FILLING OUT

(1)

The calculation of the foregoing percentage is based on 96,380,102 shares of Common Stock outstanding as of December 31, 2017, as provided by the Issuer.

CUSIP NO. 702149105

13G

PAGE 7 OF 28

1	NAME OF REPORTING PERSON
	THL Coinvestment Partners, L.P.

2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
	(a)☐
	(b)☒
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
			-0-

		6	SHARED VOTING POWER
			793,994

		7	SOLE DISPOSITIVE POWER
			-0-

		8	SHARED DISPOSITIVE POWER
			793,994

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
	793,994

10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*


11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
	0.82% (1)

12	TYPE OF REPORTING PERSON*
	PN

*SEE INSTRUCTIONS BEFORE FILLING OUT

(1)

The calculation of the foregoing percentage is based on 96,380,102 shares of Common Stock outstanding as of December 31, 2017, as provided by the Issuer.

CUSIP NO. 702149105

13G

PAGE 8 OF 28

1	NAME OF REPORTING PERSON
	THL Operating Partners, L.P.

2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
	(a)☐
	(b)☒
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
			-0-

		6	SHARED VOTING POWER
			64,245

		7	SOLE DISPOSITIVE POWER
			-0-

		8	SHARED DISPOSITIVE POWER
			64,245

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
	64,245

10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*


11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
	0.07% (1)

12	TYPE OF REPORTING PERSON*
	PN

*SEE INSTRUCTIONS BEFORE FILLING OUT

(1)

The calculation of the foregoing percentage is based on 96,380,102 shares of Common Stock outstanding as of December 31, 2017, as provided by the Issuer.

CUSIP NO. 702149105

13G

PAGE 9 OF 28

1	NAME OF REPORTING PERSON
	THL Equity Fund VI Investors (PC), L.P.

2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
	(a)☐
	(b)☒
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
			-0-

		6	SHARED VOTING POWER
			12,361,376

		7	SOLE DISPOSITIVE POWER
			-0-

		8	SHARED DISPOSITIVE POWER
			12,361,376

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
	12,361,376

10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*


11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
	12.83% (1)

12	TYPE OF REPORTING PERSON*
	PN

*SEE INSTRUCTIONS BEFORE FILLING OUT

(1)

The calculation of the foregoing percentage is based on 96,380,102 shares of Common Stock outstanding as of December 31, 2017, as provided by the Issuer.

CUSIP NO. 702149105

13G

PAGE 10 OF 28

1	NAME OF REPORTING PERSON
	Great-West Investors, LP

2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
	(a)☐
	(b)☒
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
			-0-

		6	SHARED VOTING POWER
			128,212

		7	SOLE DISPOSITIVE POWER
			-0-

		8	SHARED DISPOSITIVE POWER
			128,212

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
	128,212

10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*


11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
	0.13% (1)

12	TYPE OF REPORTING PERSON*
	PN

*SEE INSTRUCTIONS BEFORE FILLING OUT

(1)

The calculation of the foregoing percentage is based on 96,380,102 shares of Common Stock outstanding as of December 31, 2017, as provided by the Issuer.

CUSIP NO. 702149105

13G

PAGE 11 OF 28

1	NAME OF REPORTING PERSON
	Putnam Investments Employees’ Securities Company III LLC

2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
	(a)☐
	(b)☒
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
			-0-

		6	SHARED VOTING POWER
			127,765

		7	SOLE DISPOSITIVE POWER
			-0-

		8	SHARED DISPOSITIVE POWER
			127,765

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
	127,765

10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*


11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
	0.13% (1)

12	TYPE OF REPORTING PERSON*
	OO

*SEE INSTRUCTIONS BEFORE FILLING OUT

(1)

The calculation of the foregoing percentage is based on 96,380,102 shares of Common Stock outstanding as of December 31, 2017, as provided by the Issuer.

CUSIP NO. 702149105

13G

Item 1 (a).

Name of Issuer:

Party City Holdco Inc.

Item 1 (b).

Address of Issuer’s Principal Executive Offices:

80 Grasslands Road

Elmsford, NY 10523

Item 2 (a).

Name of Person Filing:

This statement is being filed on behalf of the following (collectively, the “Reporting Persons): (1) Thomas H. Lee Advisors, LLC, a Delaware limited liability company (“Advisors”); (2) Thomas H. Lee Equity Fund VI, L.P., a Delaware limited partnership (“THL Equity VI”); (3) Thomas H. Lee Parallel Fund VI, L.P., a Delaware limited partnership (“Parallel Fund VI”); (4) Thomas H. Lee Parallel (DT) Fund VI, L.P., a Delaware limited partnership (“DT Fund VI”); (5) THL Coinvestment Partners, L.P., a Delaware limited partnership (“THL Coinvestment”); (6) THL Operating Partners, L.P., a Delaware limited partnership (“THL Operating”); (7) THL PC Topco, L.P., a Delaware limited partnership (“THL Topco”); (8) THL Equity Fund VI Investors (PC), L.P., a Delaware limited partnership (“THL PC”); (9) Great-West Investors, L.P., a Delaware limited partnership (“Great West”); (10) Putnam Investments Employees’ Securities Company III LLC, a Delaware limited liability company (“Putnam III”). Entities (1) through (8) are referred to as the “THL Entities”.

Advisors is the general partner of Thomas H. Lee Partners, L.P., which in turn is the general partner of THL Coinvestment and the sole member of THL Equity Advisors VI, LLC (“THL Advisors VI”), which in turn is the general partner of the THL Equity VI, Parallel Fund VI, DT Fund VI, THL Operating, THL Topco and THL PC. THL Advisors is attorney-in-fact of Great West and Putnam Investments, LLC, which is the managing member of Putnam Investments Holdings, LLC, which in turn is the managing member of Putnam III.

Item 2 (b).

Address of Principal Business Office or, if none, Residence:

For the THL Entities:

c/o Thomas H. Lee Partners, L.P.

100 Federal Street, 35th Floor

Boston, MA 02110

For Great West:

Great-West Investors, L.P.

8515 East Orchard Road, 3T2

Greenwood Village, CO 80111

Page 12 of 28

CUSIP NO. 702149105

13G

For Putnam III:

c/o Putnam Investments, LLC

One Post Office Square

Boston, MA 02109

Item 2 (c).

Citizenship:

Thomas H. Lee Advisors, LLC – Delaware

Thomas H. Lee Equity Fund VI, L.P. – Delaware

Thomas H. Lee Parallel Fund VI, L.P. – Delaware

Thomas H. Lee Parallel (DT) Fund VI, L.P. – Delaware

THL Coinvestment Partners, L.P. – Delaware

THL Operating Partners, L.P. – Delaware

THL PC Topco, L.P. – Delaware

THL Equity Fund VI Investors (PC), L.P. – Delaware

Great-West Investors, LP – Delaware

Putnam Investments Employees’ Securities Company III LLC – Delaware

Item 2 (d).

Title of Class of Securities:

Common Stock, par value $0.01 per share

Item 2 (e).

CUSIP Number:

702149105

Item 3.

Not Applicable

Item 4

Ownership

Item 4(a)

Amount Beneficially Owned

This Schedule 13G is being filed on behalf of the Reporting Persons. The Reporting Persons may be deemed to beneficially own in the aggregate 57,716,258 shares of the Issuer’s Common Stock, representing, in the aggregate, 59.88% of the Issuer’s Common Stock. The percentage of Common Stock held by the Reporting Persons is based on 96,380,102 shares of Common Stock of the Issuer outstanding as of December 1, 2017 (the “Outstanding Shares”), as provided by the Issuer.

The following shares were owned by the Reporting Persons on December 31, 2017:

Advisors owned 57,716,258 shares of the Issuer, representing approximately 59.88% of the Outstanding Shares.

THL Topco owned 57,716,258 shares of the Issuer, representing approximately 59.88% of the Outstanding Shares.

Page 13 of 28

CUSIP NO. 702149105

13G

THL Equity VI owned 24,640,697 shares of the Issuer, representing approximately 25.57% of the Outstanding Shares.

Parallel Fund VI owned 16,685,370 shares of the Issuer, representing approximately 17.31% of the Outstanding Shares.

DT Fund VI owned 2,914,599 shares of the Issuer, representing approximately 3.02% of the Outstanding Shares.

THL Coinvestment owned 793,994 shares of the Issuer, representing approximately 0.82% of the Outstanding Shares.

THL Operating owned 64,245 shares of the Issuer, representing approximately 0.07% of the Outstanding Shares.

THL PC owned 12,361,376 shares of the Issuer, representing approximately 12.83% of the Outstanding Shares.

Great West owned 128,212 shares of the Issuer, representing approximately 0.13% of the Outstanding Shares.

Putnam III owned 127,765 shares of the Issuer, representing approximately 0.13% of the Outstanding Shares.

Each of the Reporting Persons disclaims beneficial ownership of the shares listed in this report, and this report shall not be deemed an admission that any of the Reporting Persons is the beneficial owner of the securities for the purpose of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein.

Item 4(b)

Percent of Class

See Item 4(a) hereof.

Item 4(c)

Number of Shares as to which Such Person has:

(i)

Sole power to vote or to direct the vote:

See Item 5 of each cover page

(ii)

Shared power to vote or to direct the vote:

See Item 6 of each cover page

(iii)

Sole power to dispose or to direct the disposition of:

See Item 7 of each cover page

(iv)

Shared power to dispose or to direct the disposition of:

See Item 8 of each cover page

Item 5.

Ownership of Five Percent or Less of a Class

Not applicable.

Page 14 of 28

CUSIP NO. 702149105

13G

Item 6.

Ownership of More Than Five Percent on Behalf of Another Person

The responses of the Reporting Persons to Items 2(a) and 4(a) are incorporated herein by reference. Other than set forth herein, no knowledge of anyone owning 5% or more.

Under certain circumstances, partners or members of a Reporting Person, as the case may be, could have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, shares of Common Stock owned by such Reporting Person.

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 Item 4(a) above.

Item 9.

Notice of Dissolution of Group

Not Applicable.

Item 10.

Certification

Not Applicable.

Page 15 of 28

SIGNATURE