UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE 14A

(Rule 14a-101)

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of

the Securities Exchange Act of 1934

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☐	Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))
☐	Definitive Proxy Statement
☒	Definitive Additional Materials
☐	Soliciting material Pursuant to §240.14a-12

Automatic Data Processing, Inc.

(Name of Registrant as Specified In Its Charter)

William A. Ackman

Veronica M. Hagen

V. Paul Unruh

Pershing Square Capital Management, L.P.

PS Management GP, LLC

Pershing Square, L.P.

Pershing Square II, L.P.

Pershing Square International, Ltd.

Pershing Square Holdings, Ltd.

Pershing Square VI Master, L.P.

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

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On October 30, 2017, Pershing Square Capital Management, L.P. and certain affiliates issued the following press release:

Pershing Square to Hold Webcast on November 1 at 10:00 AM EDT

New York, NY – October 30, 2017 //- Pershing Square Capital Management, L.P. (“Pershing Square”) today announced that it will hold a public webcast for ADP (NASDAQ:ADP) shareholders on Wednesday, November 1, 2017, at 10:00 AM EDT at www.ADPascending.com.

On the webcast, Pershing Square will summarize its plan to transform ADP to drive meaningfully higher margins and growth, address certain misleading information that ADP has communicated to shareholders, detail the choice that shareholders have at the November 7^th annual meeting and answer questions from ADP shareholders and analysts.

Participants who would like to ask a question following the presentation should join the event by phone. Dial-in information will be posted to www.ADPascending.com on November 1^st before the webcast begins.

A replay of the webcast will be available following the presentation at www.ADPascending.com.

For additional information, visit our website: www.ADPascending.com. Follow ADPascending on Facebook, Twitter and YouTube.

To vote for Pershing Square’s Nominees for ADP’s Transformation and ensure that Bill Ackman is elected to the board, shareholders should vote the GOLD Proxy Card or GOLD Voting Instruction Form.

THE ONLY WAY TO VOTE FOR BILL ACKMAN AND THE NOMINEES FOR ADP’S TRANSFORMATION IS TO VOTE ON THE GOLD PROXY CARD OR VOTING INSTRUCTION FORM.

You can vote by Internet, telephone or by signing and dating the GOLD Proxy Card or Voting Instruction Form and mailing it in the postage paid envelope provided. We urge you NOT to vote using any white proxy card or voting instruction form you receive from ADP. Please discard the white proxy card.

If you have any questions about how to vote your shares, please contact our proxy solicitor, D.F. King & Co., Inc., at (866) 342-1635.

About Pershing Square Capital Management, L.P.

Pershing Square Capital Management, L.P., based in New York City, is a SEC-registered investment advisor to investment funds.

Media Contact:

Pershing Square

Fran McGill

212 909 2455, McGill@persq.com

This press release relates to Pershing Square’s solicitation of proxies in connection with the 2017 annual meeting of stockholders of ADP.

The information contained in this press release (the “Information”) is based on publicly available information about Automatic Data Processing, Inc. (“ADP” or the “Company”), which has not been independently verified by Pershing Square Capital Management, L.P. (“Pershing Square”). Pershing

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Square recognizes that there may be confidential or otherwise non-public information in the possession of ADP or others that could lead ADP or others to disagree with Pershing Square’s conclusions. This press release and the Information is not a recommendation or solicitation to buy or sell any securities.

The analyses provided may include certain forward-looking statements, estimates and projections prepared with respect to, among other things, general economic and market conditions, changes in management, changes in board composition, actions of ADP and its subsidiaries or competitors, the ability to implement business strategies and plans and pursue business opportunities in the human capital management industry. Such forward-looking statements, estimates, and projections reflect various assumptions by Pershing Square concerning anticipated results that are inherently subject to significant uncertainties and contingencies and have been included solely for illustrative purposes, including those risks and uncertainties detailed in the continuous disclosure and other filings of ADP with the Securities and Exchange Commission at www.sec.gov. No representations, express or implied, are made as to the accuracy or completeness of such forward-looking statements, estimates or projections or with respect to any other materials herein. Actual results may vary materially from the estimates and projected results contained herein.

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