13D Filing: Par Investment Partners Lp and Trivago N.v. (TRVG)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No.     )*

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)

c/o 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)

April 4, 2017

(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).

Item 1. SECURITY AND ISSUER

This Statement on Schedule 13D relates to the Class A Shares (the Class A Shares) of trivago N.V. (the Issuer) that
are held directly by PAR Investment Partners, L.P., a Delaware limited partnership (PAR Investment Partners), through American Depositary Shares, each representing one Class A Share. The address of the Issuers principal
executive office is Bennigsen-Platz 1, 40474, Düsseldorf, Germany. Information given in response to each item shall be deemed incorporated by reference in all other items, as applicable.

Item 2. IDENTITY AND BACKGROUND

(a), (b) and
(c) This statement is being filed by the following persons: PAR Investment Partners, PAR Group, L.P., a Delaware limited partnership (PAR Group), and PAR Capital Management, Inc., a Delaware corporation (PAR Capital
Management). PAR Investment Partners, PAR Group and PAR Capital Management are sometimes individually referred to herein as a Reporting Person and collectively as the Reporting Persons.

The principal business of PAR Investment Partners is that of a private investment partnership engaging in the purchase and sale of securities for its own
account and its address is 200 Clarendon Street, 48^th Floor, Boston, MA 02116. The sole general partner of PAR Investment Partners is PAR Group. The principal business of PAR Group is to act as
the general partner of PAR Investment Partners and its address is 200 Clarendon Street, 48^th Floor, Boston, MA 02116. The sole general partner of PAR Group is PAR Capital Management. The principal
business of PAR Capital Management is to act as the general partner of PAR Group and its address is 200 Clarendon Street, 48^th Floor, Boston, MA 02116.

Paul A. Reeder, III is the President and sole director of PAR Capital Management and each of Frederick S. Downs, Jr., Arthur G. Epker, III, Edward L. Shapiro,
Steven M. Smith, Michael J. Tucker and Herbert A. (Chip) Frazier is a shareholder of PAR Capital Management. The business address of each of Mr. Reeder, Mr. Downs, Mr. Epker, Mr. Smith, Mr. Tucker and
Mr. Frazier is 200 Clarendon Street, 48^th Floor, Boston, MA 02116.

(d) and (e) During the
last five years, none of the persons identified in this Item 2 has been convicted in any criminal proceeding (excluding traffic violations or similar misdemeanors), or has been a party to any civil proceeding of a judicial or administrative
body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, Federal or state securities laws or finding
any violations with respect to such laws.

(f) Each natural person identified in this Item 2 is a citizen of the United States. PAR Investment
Partners and PAR Group are Delaware limited partnerships and PAR Management is a Delaware corporation.

Item 3. SOURCE AND AMOUNT OF FUNDS OR
OTHER CONSIDERATION

PAR Investment Partners used approximately $73.3 mn (including brokerage commissions) of the working capital of PAR Investment
Partners in the aggregate to purchase the Class A Shares reported in this Schedule 13D. Such Class A Shares are or may be held from time to time by PAR Investment Partners in margin accounts established with its brokers or banks and a
portion of the purchase price for the Class A Shares may be obtained through margin borrowing. Securities positions which may be held in the margin accounts, including the Class A Shares, may be pledged as collateral security for the
repayment of debit balances in the margin accounts.

Item 4. PURPOSE OF TRANSACTION

The Reporting Persons acquired the Class A Shares for investment purposes in the ordinary course of their business of investing in securities for their
own accounts or for one or more accounts over which the Reporting Persons have investment or voting power. The Reporting Persons reserve the right to formulate plans and/or make proposals, and take such actions with respect to their investment in
the Issuer, including, subject to applicable law, (i) to hold the Class A Shares as a passive investor or as an active investor (whether or not as a member of a group with other

beneficial owners of Shares or otherwise), (ii) to acquire beneficial ownership of additional shares in the open market, in privately negotiated transactions or otherwise, (iii) to
dispose of all or part of its holdings, (iv) to take other actions which could involve one or more of the types of transactions or have one or more of the results described in Item 4 of this Schedule 13D, or (v) to change its
intention with respect to any or all of the matters referred to in this Item 4.

Item 5. INTEREST IN SECURITIES OF THE ISSUER

(a)-(b) As of April 13, 2017, PAR Investment Partners may be deemed to beneficially own 6,234,000 Class A Shares, representing approximately
20.8% (determined in accordance with Rule 13d-3 under the Act) of the outstanding Class A Shares.

As of April 13, 2017, PAR Group, through its
control of PAR Investment Partners as general partner, may be deemed to beneficially own 6,234,000 Class A Shares, representing approximately 20.8% (determined in accordance with Rule 13d-3 under the Act) of the outstanding Class A Shares.

As of April 13, 2017, PAR Capital Management, through its control of PAR Group as general partner, may be deemed to beneficially own 6,234,000
Class A Shares, representing approximately 20.8% (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 are based on 30,026,635 Class A Shares issued and outstanding as of
December 31, 2016, as disclosed in the Issuers Annual Report on Form 20-F filed with the Securities and Exchange Commission on March 9, 2017.

(c) Information with respect to all transactions by the Reporting Persons relating to the Class A Shares that were effected during the past sixty days is
set forth in Annex A hereto and is incorporated by reference herein.

ITEM 6. CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH RESPECT TO
SECURITIES OF THE ISSUER.

Except as otherwise set forth in this Schedule 13D, 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.

Item 7.
Material to be Filed as Exhibits.

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.

Date: April 13, 2017

Annex A

TRANSACTIONS IN CLASS A SHARES BY THE REPORTING PERSONS

The following table sets forth all transactions relating to the Class A Shares effected by the Reporting Persons in the past sixty days that have not
been previously reported on Schedule 13D. Unless otherwise noted, all such transactions were effected in the open market through a broker and all prices per share include commissions.

PAR Investment Partners, L.P.