Exhibit 99.1

Name and Address of Reporting Person:	Thomas H. Lee Advisors, LLC
	c/o Thomas H. Lee Partners, L.P.
	100 Federal Street, 35th Floor
	Boston, MA 02110

Issuer Name and Ticker or Trading Symbol:	Party City Holdco Inc.

Date of Earliest Transaction Required to be Reported (Month/Day/Year):	May 18, 2018

Footnotes to Form 4

(1) This report is being filed by the following Reporting Persons: Thomas H. Lee Advisors, LLC (“THL Advisors”), Thomas H. Lee Equity Fund VI, L.P. (“THL Equity VI”), Thomas H. Lee Parallel Fund VI, L.P. (“Parallel Fund VI”), Thomas H. Lee Parallel (DT) Fund VI, L.P. (“DT Fund VI”), THL Coinvestment Partners, L.P. (“THL Coinvestment”), THL Operating Partners, L.P. (“THL Operating”), THL PC Topco, L.P. (“THL Topco”), THL Equity Fund VI Investors (PC), L.P. (“THL PC”) together with THL Equity VI, Parallel Fund VI, DT Fund VI, THL Coinvestment, THL Operating, THL Topco and THL PC, (the “THL Funds”) as well as Great-West Investors, L.P. (“Great West”) and Putnam Investments Employees’ Securities Company III LLC (“Putnam III”); Todd M. Abbrecht, Joshua M. Nelson, Uttam K. Jain and Douglas A. Haber. This Form 4 is in two parts and is jointly filed with the Reporting Persons in both parts. See Remarks.

(2) THL 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.

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

(4) Represents shares of common stock held directly and sold by THL Topco, although such shares are beneficially owned by the following entities: 5,123,139 shares sold by THL Equity VI; 3,469,117 shares sold by Parallel Fund VI; 605,985 shares sold by DT Fund VI; 165,082 shares sold by THL Coinvestment; 13,357 shares sold by THL Operating; 2,570,099 shares sold by THL PC; 26,657 shares sold by Great West; and 26,564 shares sold by Putnam III.

(5) Represents shares of common stock held directly following the transaction by THL Topco, although such shares are beneficially owned by the following entities: 19,517,558 shares owned by THL Equity VI; 13,216,253 shares owned by Parallel Fund VI; 2,308,614 shares owned by DT Fund VI; 628,912 shares owned by THL Coinvestment; 50,888 shares owned by THL Operating; 9,791,277 shares owned by THL PC; 101,555 shares owned by Great West; and 101,201 shares owned by Putnam III.

THL Coinvestment Partners, L.P. 4