13D Filing: PAR Capital and United Continental Holdings, Inc. (UAL)

SCHEDULE 13D

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 1)*

United
Continental Holdings, Inc.

(Name of Issuer)

Common Stock, $0.01 par value

(Title of Class of Securities)

910047109

(CUSIP Number)

PAR Capital Management, Inc.

Attn: Steven M. Smith

One International Place, Suite 2401

Boston, MA 02110

(617)
526-8990

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

February 5, 2016

(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).

SCHEDULE 13D

SCHEDULE 13D

SCHEDULE 13D

SCHEDULE 13D

This
Amendment No. 1 (this Amendment) to Schedule 13D (the Schedule 13D) is being filed by PAR Investment Partners, L.P., a Delaware limited partnership (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. Capitalized terms used but not otherwise defined in this Amendment shall have the meanings ascribed to them in the
Schedule 13D. Except as otherwise specifically amended in this Amendment, items in the Schedule 13D remain unchanged.

Item 3. SOURCE AND AMOUNT
OF FUNDS OR OTHER CONSIDERATION

Item 3 of Schedule 13D is hereby amended and restated as follows:

PAR Investment Partners used approximately $709,203,281 (including brokerage commissions) of the working capital of PAR Investment Partners in the aggregate
to purchase the shares of Common Stock reported in this Schedule 13D. Such shares of Common Stock 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 Common Stock may be obtained through margin borrowing. Securities positions which may be held in the margin accounts, including the Common Stock, may be pledged as collateral security for the repayment of debit balances in the margin
accounts.

Item 4. PURPOSE OF TRANSACTION

Item 4 of Schedule 13D is hereby amended by adding the following paragraph to the end thereof:

On February 5, 2016, the Reporting Persons were granted early termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of
1976, as amended.

Item 5. INTEREST IN SECURITIES OF THE ISSUER

Item 5 of Schedule 13D is hereby amended and restated as follows:

(a)-(b) As of February 10, 2016, PAR Investment Partners may be deemed to beneficially own 14,134,711 shares of Common Stock, representing
approximately 3.8% (determined in accordance with Rule 13d-3 under the Act) of the outstanding Common Stock.

As of February 10, 2016, PAR Group,
through its control of PAR Investment Partners as general partner, may be deemed to beneficially own 14,134,711 shares of Common Stock, representing approximately 3.8% (determined in accordance with Rule 13d-3 under the Act) of the outstanding
Common Stock.

As of February 10, 2016, PAR Capital Management, through is control of PAR Group as general partner, may be deemed to beneficially own
14,134,711 shares of Common Stock, representing approximately 3.8% (determined in accordance with Rule 13d-3 under the Act) of the outstanding Common Stock.

The percentage of shares of the Common Stock beneficially owned as set forth above are based on 372,810,266 shares of Common Stock outstanding as of
October 13, 2015, as disclosed in the Issuers Quarterly Report on Form 10-Q, for the period ended September 30, 2015, filed on October 22, 2015.

SCHEDULE 13D

Representatives of the Reporting Persons have engaged in discussions with Altimeter Capital Management, Inc. (Altimeter) regarding
strategies to enhance shareholder value in the Issuer. As a result, the Reporting Persons may be deemed members of a group with Altimeter as defined in Rule 13d-5 of the Securities Exchange Act of 1934, as amended (the Exchange
Act). Pursuant to such definition, the Reporting Persons and Altimeter may be deemed to beneficially own the shares of Common Stock beneficially owned by each other solely for such purposes. Altimeter has advised the Reporting Persons that
it is the beneficial owner of 11,500,668 shares of Common Stock, or 3.1% of the outstanding Common Stock. Based upon such advice, the Reporting Persons and Altimeter beneficially own a combined 25,635,379 shares of Common Stock, or 6.9% of the
outstanding Common Stock. The Reporting Persons expressly disclaim beneficial ownership of any shares of Common Stock held by Altimeter and/or its affiliates. Accordingly, Items 11 and 13 of the cover pages to this Schedule 13D set forth the
aggregate number and percentage of outstanding shares of Common Stock that are beneficially owned by the Reporting Persons. The Reporting Persons (i) own (and will continue to own) less than 5% of the total outstanding Common Stock for purposes
of Treasury Regulation Section 1.382-2T(g), (ii) have the sole right to dividends and/or proceeds from the sale of the Common Stock reported in Item 11 of this Schedule 13D and have no dividend or voting rights in any other shares of
Common Stock, and (iii) do not have any formal or informal understanding with Altimeter or any other stockholder of the Issuer to make any coordinated acquisitions of, or investment decisions with respect to, the Common Stock.

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

(d) Not applicable.

(e) Not applicable.

SCHEDULE 13D

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: February 10,
2016

SCHEDULE 13D

Annex A

TRANSACTIONS IN COMMON STOCK BY THE REPORTING PERSONS

The following tables set forth all transactions relating to the Common Stock 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.