Cubist Pharmaceuticals (CBST) DEFA14A Additional proxy soliciting materials

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 14A
Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No.     )
Filed by the Registrant  x
Filed by a Party other than the Registrant  o
Check the appropriate box:
o	Preliminary Proxy Statement
o	Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))
o	Definitive Proxy Statement
x	Definitive Additional Materials
o	Soliciting Material Pursuant to §240.14a-12
Cubist Pharmaceuticals, Inc.
(Name of Registrant as Specified In Its Charter)
(Name of Person(s) Filing Proxy Statement, if other than the Registrant)
Payment of Filing Fee (Check the appropriate box):
x	No fee required.
o	Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11.
	(1)		Title of each class of securities to which transaction applies:
	(2)		Aggregate number of securities to which transaction applies:
	(3)		Per unit price or other underlying value of transaction computed pursuant to Exchange Act Rule 0-11 (set forth the amount on which the filing fee is calculated and state how it was determined):
	(4)		Proposed maximum aggregate value of transaction:
	(5)		Total fee paid:
o	Fee paid previously with preliminary materials.
o	Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing for which the offsetting fee was paid previously. Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing.
	(1)	Amount Previously Paid:
	(2)	Form, Schedule or Registration Statement No.:
	(3)	Filing Party:
	(4)	Date Filed:

<STOCK#> 123456 C0123456789 12345 C 1234567890 MR ANDREW SAMPLE 1234 AMERICA DRIVE ANYWHERE, IL 60661 www.envisionreports.com/CBST Step 1: Go to www.envisionreports.com/CBST to view the materials. Step 2: Click on Cast Your Vote or Request Materials. Step 3: Follow the instructions on the screen to log in. Notice of Internet Availability of Proxy Materials 011SGA IMPORTANT ANNUAL STOCKHOLDERS’ MEETING INFORMATION — YOUR VOTE COUNTS! + + Important Notice Regarding the Internet Availability of Proxy Materials for the 2009 Annual Meeting of Stockholders of Cubist Pharmaceuticals, Inc. to be Held on June 4, 2009. Under new Securities and Exchange Commission rules, you are receiving this notice that the proxy materials for the annual stockholders’ meeting are available on the Internet. Follow the instructions below to view the materials and vote online or request a copy. The items to be voted on are on the reverse side. Your vote is important! This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. We encourage you to access and review all of the important information contained in the proxy materials before voting. The proxy statement and annual report to stockholders are available at:  Easy Online Access — A Convenient Way to View Proxy Materials and Vote When you go online to view materials, you can also vote your shares. Step 4: Make your selection as instructed on each screen to select delivery preferences and vote. When you go online, you can also help the environment by consenting to receive electronic delivery of future materials. Obtaining a Copy of the Proxy Materials – If you want to receive a paper or e-mail copy of these documents, you must request one. There is no charge to you for requesting a copy. Please make your request for a copy as instructed on the reverse side on or before May 25, 2009 to facilitate timely delivery.

Directions to the 2009 Annual Meeting of Stockholders of Cubist Pharmaceuticals, Inc. Here’s how to order a copy of the proxy materials and select a future delivery preference: Paper copies: Current and future paper delivery requests can be submitted via the telephone, Internet or email options below. Email copies: Current and future email delivery requests must be submitted via the Internet following the instructions below. If you request an email copy of current materials you will receive an email with a link to the materials. PLEASE NOTE: You must use the numbers in the shaded bar on the reverse side when requesting a set of proxy materials. Internet – Go to www.envisionreports.com/CBST. Click Cast Your Vote or Request Materials. Follow the instructions to log in and order a paper or email copy of the current meeting materials and submit your preference for email or paper delivery of future meeting materials. Telephone – Call us free of charge at 1-866-641-4276 using a touch-tone phone and follow the instructions to log in and order a paper copy of the materials by mail for the current meeting. You can also submit a preference to receive a paper copy for future meetings. Email – Send email to investorvote@computershare.com with “Proxy Materials Cubist” in the subject line. Include in the message your full name and address, plus the three numbers located in the shaded bar on the reverse, and state in the email that you want a paper copy of current meeting materials. You can also state your preference to receive a paper copy for future meetings. To facilitate timely delivery, all requests for a paper copy of the proxy materials must be received by May 25, 2009. To obtain directions to attend the 2009 Annual Meeting of Stockholders and vote in person, please visit www.cubist.com. Notice of Internet Availability of Proxy Materials The 2009 Annual Meeting of Stockholders of Cubist Pharmaceuticals, Inc. will be held on June 4, 2009 at 55 Hayden Avenue, Lexington, MA 02421, at 8:30 a.m. Eastern Time. Proposals to be voted on at the meeting are listed below along with the Board of Directors’ recommendations. The Board of Directors recommends that you vote FOR all the nominees listed and FOR Proposals 2, 3 and 4: 1. Election of the Class I Directors: 01 - Kenneth Bate, 02 - Nancy Hutson, 03 - Martin Soeters. 2. A proposal to amend our Amended and Restated 1997 Employee Stock Purchase Plan, or ESPP, to increase the number of shares issuable under the ESPP by 500,000. 3. A proposal to amend our Amended and Restated 2002 Directors’ Equity Incentive Plan, or Directors’ Plan, to extend the term of the Directors’ Plan by three years and to increase the number of shares issuable under the Directors’ Plan by 400,000. 4. A proposal to ratify the selection of PricewaterhouseCoopers LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2009. PLEASE NOTE – YOU CANNOT VOTE BY RETURNING THIS NOTICE. To vote your shares you must vote online or request a paper copy of the proxy materials to receive a proxy card. 011SGA