13D Filing: Ontario Teachers Pension Plan Board and Macerich Co (MAC)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 3)*

The Macerich
Company

(Name of Issuer)

Common Stock, Par Value $0.01 Per Share

(Title of Class of Securities)

554382101

(CUSIP Number)

Jeff Davis

Senior Vice President and General Counsel

Ontario Teachers Pension Plan Board

5650 Yonge Street, 3rd Floor

Toronto, Ontario M2M 4H5

Canada

(416) 228-5900

With a Copy to:

William G. Farrar

Sullivan & Cromwell LLP

125 Broad Street

New
York, New York 10004

(212) 558-4940

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

February 23, 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 (the 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

This Amendment No. 3 (this Amendment No. 3) amends and supplements the
statement on Schedule 13D filed with the Securities and Exchange Commission (the SEC) on November 24, 2014 (the Original Schedule 13D), Amendment No. 1 to the Original Schedule 13D filed with the SEC on May 8,
2015 (Amendment No. 1) and Amendment No. 2 to the Original Schedule 13D filed with the SEC on May 15, 2015 (Amendment No. 2, and together with the Original Schedule 13D, Amendment No. 1 and this
Amendment No. 3, the Schedule 13D) with respect to the common stock, par value $0.01 per share (the Common Stock), of The Macerich Company, a Maryland corporation (the Issuer), filed by Ontario Teachers
Pension Plan Board, an Ontario, Canada corporation (Teachers), and 1700480 Ontario Inc., an Ontario, Canada corporation (1700480), wholly owned by Teachers. Capitalized terms used herein and not otherwise defined
have the meanings assigned to such terms in the Original Schedule 13D. All items or responses not described herein remain as previously reported in the Original Schedule 13D, as amended and supplemented by Amendment No. 1 and Amendment
No. 2.

All calculations with respect to beneficial ownership of the Issuers Common Stock set forth in this Schedule 13D are
based on 149,149,560 shares of Common Stock outstanding as of February 22, 2016, as reported on the cover of the Issuers Annual Report on Form 10-K for the fiscal year ended December 31, 2015 (the Form 10-K), filed with
the SEC by the Issuer on February 23, 2016.

Item 2 of the Schedule 13D is hereby amended solely with
respect to Schedule A and Schedule B attached hereto.

Item 3 of the Schedule 13D is
hereby amended and supplemented by adding the following immediately after the last paragraph thereof:

The 1,186,000 shares of Common
Stock acquired by 1700480 between May 18, 2015 and May 19, 2015 reported herein were acquired at an aggregate purchase price of $98,693,989. The source of the funds used to purchase such shares of Common Stock was a capital contribution to
equity by 1700480s parent, Teachers.

In addition, according to its Form 10-K, the Issuer repurchased 9,333,590 shares of its
Common Stock between November 12, 2015 and February 17, 2016. As a result of the acquisition of shares of Common Stock by 1700480 and the Issuers repurchase of its Common Stock, the Reporting Persons beneficial ownership
percentage increased approximately 1.7% to 15.6%, with 0.9% of the approximately 1.7% increase due to the Issuers repurchase of its Common Stock.

4

Paragraphs (a) and (b) of Item 5 of
the Schedule 13D are hereby amended and restated in their entirety as follows:

(a) and (b). 1700480, as a wholly-owned subsidiary
of Teachers, may be deemed to share voting and dispositive power with Teachers with respect to the 23,286,237 shares of Common Stock it beneficially owns, representing approximately 15.6% of the shares of Common Stock outstanding.
Pursuant to the Master Agreement, 1700480 agreed that if it and its affiliates collectively own (beneficially or of record) more than 9.9% of the outstanding shares of Common Stock, 1700480 will cause to be voted in accordance with the
recommendations of the Issuers Board of Directors all of the shares of Common Stock owned by them in excess of such number of shares that represents 9.9% of the outstanding shares of Common Stock. The foregoing summary of the Master Agreement
is qualified in its entirety by reference to the full text of the Master Agreement.

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Signatures

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.

March 9, 2016

SCHEDULE A

CERTAIN INFORMATION REGARDING THE BOARD MEMBERS AND OFFICERS

OF ONTARIO TEACHERS PENSION PLAN BOARD

Set forth in the table below are the name, current residence or business address and current occupation or employment of each of the board
members and officers of Ontario Teachers Pension Plan Board, an Ontario, Canada corporation (Teachers). Each director and officer is a citizen of Canada with the exception of: (i) Kathleen ONeill who is a citizen
of Canada and Ireland; (ii) Neil Bisset who is a citizen of the United Kingdom and Canada; (iii) Charley Butler who is a citizen of the United Kingdom; (iv) Doug Gerhart who is a citizen of Canada and the United States;
(v) Bjarne Graven Larsen who is a citizen of Denmark; and (vi) Calum McNeil and Andrew Jonathan Mark Taylor, each of whom is a citizen of the United Kingdom.

SCHEDULE B

CERTAIN INFORMATION REGARDING THE DIRECTORS

AND EXECUTIVE OFFICERS OF 1700480 ONTARIO INC.

Set forth in the table below are the name, current residence or business address and current occupation or employment of each of the directors
and executive officers of 1700480 Ontario Inc., an Ontario, Canada corporation. Each director and officer is a citizen of Canada with the exception of Russell Goin, who is a citizen of the United States.