UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 9)*

trivago N.V.

(Name of Issuer)

Class A Shares, nominal value of €0.06 per share

(Title of Class of Securities)

89686D105 (for American Depositary Shares, each representing one Class A Share)

(CUSIP Number)

PAR Investment Partners, L.P.

200 Clarendon Street, 48^th Floor

Boston, MA 02116

Attn: Steven M. Smith

(617) 526-8990

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

May 21, 2021

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box:

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

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).

CUSIP No. 89686D105

CUSIP No. 89686D105

CUSIP No. 89686D105

Introduction

This Amendment No. 9 to Schedule 13D amends Amendment No. 8 to Schedule 13D filed on May 14, 2021, which amended Amendment No. 7 to Schedule 13D filed on April 14, 2021, which amended Amendment No. 6 to Schedule 13D filed on March 26, 2021, which amended Amendment No. 5 to Schedule 13D filed on February 26, 2021, which amended Amendment No. 4 to Schedule 13D filed on February 10, 2021, which amended, Amendment No. 3 to Schedule 13D filed on February 1, 2021, which amended Amendment No. 2 to Schedule 13D filed on January 29, 2021, which amended Amendment No. 1 to Schedule 13 filed on June 13, 2019, which amended the Statement on Schedule 13D filed on September 18, 2018 (the “Schedule 13D”), and is being filed by PAR Investment Partners, L.P., a Delaware limited partnership (“PAR Investment Partners”), PAR Group II, L.P., a Delaware limited partnership (“PAR Group”), and PAR Capital Management, Inc., a Delaware corporation (“PAR Capital Management” and, together with PAR Investment Partners and PAR Group, the “Reporting Persons”), and relates to the Class A Shares, nominal value of €0.06 per share (the “Class A Shares”) of trivago N.V. (the “Issuer”). The Class A Shares reported herein are represented by an equal number of American Depositary Shares (“ADSs”) that are held directly by PAR Investment Partners, L.P.

Capitalized terms used but not defined herein shall have the meanings ascribed to them in the Schedule 13D. The Schedule 13D is amended on a supplementary basis as follows; all items or responses not described herein, or exhibits not filed herewith, remain as previously reported in, or filed with, the Schedule 13D, as amended.

Item 5. INTEREST IN SECURITIES OF THE ISSUER

(a)-(b) As of May 14, 2021, each of (i) PAR Investment Partners, (ii) PAR Group, through its control of PAR Investment Partners as general partner, and (iii) PAR Capital Management, through is control of PAR Group as general partner, may be deemed to beneficially own 19,318,683 Class A Shares, representing approximately 29.8% (determined in accordance with Rule 13d-3 under the Act) of the outstanding Class A Shares.

The percentage of Class A Shares beneficially owned as set forth above is based on 64,746,247 Class A Shares issued and outstanding as of March 31, 2021, as disclosed in the Issuer’s Prospectus Supplement on Form 424B5 filed with the Securities and Exchange Commission on May 3, 2021.

(c) Other than as described in Item 4 of this report, and those described in the attached Annex I, there were no transactions by the Reporting Persons relating to the Class A Shares effected during the past sixty days.

Except as otherwise set forth in this report, there are no contracts, arrangements, understandings or relationships among the persons named in Item 2 or between such persons and any other person with respect to any securities of the Issuer.

SIGNATURE

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.

May 25, 2021

Annex I

Information With Respect to Transactions of Class A Shares during the Past 60 Days