Zoetis Inc. (ZTS): Billionaire William Ackman’s Pershing Square Sells 6 Million Shares

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

(Rule 13d-101)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT

TO § 240.13d-1(a) AND AMENDMENTS THERETO FILED

PURSUANT TO § 240.13d-2(a)

Under the Securities Exchange Act of 1934

(Amendment No. 6)*

Under the Securities Exchange Act of 1934

Zoetis Inc.

(Name of Issuer)

Common Stock, par value $0.01 per share

(Title of Class of Securities)

98978V103

(CUSIP Number)

Stephen Fraidin, Esq.

Steve Milankov, Esq.

Pershing Square Capital Management, L.P.

888 Seventh Avenue, 42nd Floor

New York, New York 10019

(212) 813-3700

With a
copy to:

Alan Sinsheimer, Esq.

Sullivan & Cromwell LLP

125 Broad Street

New
York, New York 10004

(212) 558-4000

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

July 7, 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 which
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 remainder of this cover page shall be filled out for a reporting persons initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

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).

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CUSIP No. 98978V103

1		NAME OF REPORTING PERSON Pershing Square Capital Management, L.P.
2		CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a)  ¨        (b)  ¨
3		SEC USE ONLY
4		SOURCE OF FUNDS (SEE INSTRUCTIONS) OO (See Item 3)
5		CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e) ¨
6		CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH				7		SOLE VOTING POWER NONE
				8		SHARED VOTING POWER 18,891,304
				9		SOLE DISPOSITIVE POWER NONE
				10		SHARED DISPOSITIVE POWER 18,891,304
11		AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 18,891,304
12		CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS) ¨
13		PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 3.8%*
14		TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) IA

*	This calculation is based on 496,202,370 shares of Common Stock, par value $0.01 per share (Common Stock), outstanding as of April 29, 2016 as reported in the Issuers Quarterly Report on Form 10-Q filed on May 6, 2016.

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CUSIP No. 98978V103

1		NAME OF REPORTING PERSON PS Management GP, LLC
2		CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a)  ¨        (b)  ¨
3		SEC USE ONLY
4		SOURCE OF FUNDS (SEE INSTRUCTIONS) OO (See Item 3)
5		CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e) ¨
6		CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH				7		SOLE VOTING POWER NONE
				8		SHARED VOTING POWER 18,891,304
				9		SOLE DISPOSITIVE POWER NONE
				10		SHARED DISPOSITIVE POWER 18,891,304
11		AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 18,891,304
12		CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS) ¨
13		PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 3.8%*
14		TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) OO

*	This calculation is based on 496,202,370 shares of Common Stock outstanding as of April 29, 2016 as reported in the Issuers Quarterly Report on Form 10-Q filed on May 6, 2016.

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CUSIP No. 98978V103

1		NAME OF REPORTING PERSON William A. Ackman
2		CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a)  ¨        (b)  ¨
3		SEC USE ONLY
4		SOURCE OF FUNDS (SEE INSTRUCTIONS) OO (See Item 3)
5		CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e) ¨
6		CITIZENSHIP OR PLACE OF ORGANIZATION United States
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH				7		SOLE VOTING POWER NONE
				8		SHARED VOTING POWER 18,891,304
				9		SOLE DISPOSITIVE POWER NONE
				10		SHARED DISPOSITIVE POWER 18,891,304
11		AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 18,891,304
12		CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS) ¨
13		PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 3.8%*
14		TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) IN

*	This calculation is based on 496,202,370 shares of Common Stock outstanding as of April 29, 2016 as reported in the Issuers Quarterly Report on Form 10-Q filed on May 6, 2016.

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This amendment No. 6 to Schedule 13D relates to the Schedule 13D filed on November 12,
2014, as amended prior to the date of this amendment (as so amended, the Original Schedule 13D), by (i) Pershing Square Capital Management, L.P., a Delaware limited partnership (Pershing Square),
(ii) PS Management GP, LLC, a Delaware limited liability company (PS Management), and (iii) William A. Ackman, a citizen of the United States (together with Pershing Square and PS Management, the Reporting
Persons), relating to the common stock, par value $0.01 per share (the Common Stock), of Zoetis Inc., a Delaware corporation (the Issuer). Capitalized terms used but not defined in this amendment shall
have the meanings set forth in the Original Schedule 13D.

Item 1. Security and Issuer

The second paragraph of Item 1 of the Original Schedule 13D is hereby amended and restated to read in full as follows:

The Reporting Persons (as defined below) beneficially own 18,891,304 shares of Common Stock (the Subject Shares). The
Subject Shares represent approximately 3.8% of the shares of Common Stock outstanding, based on 496,202,370 shares of Common Stock outstanding as of April 29, 2016 as reported in the Issuers Quarterly Report on Form 10-Q filed on
May 6, 2016.

Item 5. Interest in the Securities of the Issuer

Item 5(c) of the Original Schedule 13D is hereby amended and supplemented by adding the following information:

Exhibit 99.12 filed herewith and Exhibit 99.11 previously filed, both of which are incorporated herein by reference, describe all of the
transactions in shares of or derivatives relating to Common Stock that were effected by the Reporting Persons in the past 60 days. Those transactions were effected for the accounts of the Pershing Square Funds, as further specified therein.

Item 5(e) of the Original Schedule 13D is hereby amended and supplemented by adding the following information:

As of June 15, 2016, each of the Reporting Persons ceased to be the beneficial owner of more than five percent of the Common Stock.

Item 7. Material to be Filed as Exhibits

Exhibit		Description
99.12		Trading data

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SIGNATURE

After reasonable inquiry and to the best of each of the undersigneds knowledge and belief, each of the undersigned certify that the
information set forth in this statement is true, complete and correct.

Dated: July 8, 2016

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INDEX TO EXHIBITS

Exhibit Number		Description of Exhibits
Exhibit 99.1		Joint Filing Agreement, dated as of November 11, 2014, among Pershing Square, PS Management and William A. Ackman.*
Exhibit 99.2		Trading data.*
Exhibit 99.3		Letter Agreement, dated October 1, 2014, among Pershing Square on behalf of the Pershing Square Funds and SHCM.*
Exhibit 99.4		Form of Confirmation for Forward Purchase Contracts.*
Exhibit 99.5		Form of Confirmation for Delayed Settlement Puts.*
Exhibit 99.6		Form of Confirmation for Cash-Settled Swap Agreements.*
Exhibit 99.7		Trading data.*
Exhibit 99.8		February 3 Letter Agreement.*
Exhibit 99.9		Trading data.*
Exhibit 99.10		April 10 Letter.*
Exhibit 99.11		Trading data.*
Exhibit 99.12		Trading data.

*	Previously Filed