Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
OMB APPROVAL
OMB Number: 3235-0287
Expires: January 31, 2005
Estimated average burden hours per response... 0.5

(Print or Type Responses)
1. Name and Address of Reporting Person *
ECKSTEIN BERNSTEIN H CAROL
  2. Issuer Name and Ticker or Trading Symbol
CABOT MICROELECTRONICS CORP [CCMP]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
VP, Sec & General Counsel
(Last)
(First)
(Middle)
C/O CABOT MICROELECTRONICS CORPORATION, 870 COMMONS DRIVE
3. Date of Earliest Transaction (Month/Day/Year)
03/09/2012
(Street)

AURORA, IL 60504
4. If Amendment, Date Original Filed(Month/Day/Year)
6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)
2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code
(Instr. 8)
4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)
5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)
6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)
7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price
Common Stock 03/09/2012   M   54,658 A $ 34.33 89,066.517 D  
Common Stock 03/09/2012   S(1)   54,658 D $ 35.987 34,408.517 D  

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number. SEC 1474 (9-02)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)
2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code
(Instr. 8)
5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)
6. Date Exercisable and Expiration Date
(Month/Day/Year)
7. Title and Amount of Underlying Securities
(Instr. 3 and 4)
8. Price of Derivative Security
(Instr. 5)
9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)
10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)
11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Stock Options (Right to Buy) $ 34.33 (2) (14) 03/09/2012   M     54,658 05/01/2003(4) 05/01/2012 Common Stock 54,658 (2) (3) $ 0 0 D  
Stock Options (Right to Buy) $ 35.42 (14) (15)             12/11/2003(5) 12/11/2012 Common Stock 68,907 (3) (15)   68,907 D  
Stock Options (Right to Buy) $ 33.72 (14) (16)             12/11/2004(6) 12/11/2013 Common Stock 87,040 (3) (16)   87,040 D  
Stock Options (Right to Buy) $ 26.05 (14) (17)             12/10/2005(7) 12/10/2014 Common Stock 62,379 (3) (17)   62,379 D  
Stock Options (Right to Buy) $ 21.77 (14) (18)             12/01/2007(8) 12/01/2016 Common Stock 37,717 (3) (18)   37,717 D  
Stock Options (Right to Buy) $ 25.79 (14) (19)             11/30/2008(9) 11/30/2017 Common Stock 40,436 (3) (19)   40,436 D  
Stock Options (Right to Buy) $ 16 (14) (20)             12/01/2009(10) 12/01/2018 Common Stock 23,392 (3) (20)   23,392 D  
Stock Options (Right to Buy) $ 21.45 (14) (21)             12/01/2010(11) 12/01/2019 Common Stock 27,417 (3) (21)   27,417 D  
Stock Options (Right to Buy) $ 28.62 (14) (22)             12/01/2011(12) 12/01/2020 Common Stock 25,024 (3) (22)   25,024 D  
Stock Options (Right to Buy) $ 27.94 (14) (23)             12/01/2012(13) 12/01/2021 Common Stock 26,547 (3) (23)   26,547 D  

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
ECKSTEIN BERNSTEIN H CAROL
C/O CABOT MICROELECTRONICS CORPORATION
870 COMMONS DRIVE
AURORA, IL 60504
      VP, Sec & General Counsel  

Signatures

 /s/ H. Carol Bernstein   03/13/2012
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) Sale to cover exercise price of, and taxes related to, exercise of stock options.
(2) This option pursuant to the Second Amended and Restated Equity Incentive Plan ("EIP"), was previously reported by the reporting person as an option for 42,000 shares of common stock at an exercise price of $49.80.
(3) As a result of a leveraged recapitalization of the Company via a special cash dividend (the "Dividend") of $15.00 per share declared on February 13, 2012 with a record date of February 23, 2012, a payable date of March 1, 2012 and an ex-dividend date of March 2, 2012, the option award was proportionally adjusted on March 2, 2012 to preserve its value in connection with the Dividend, as required by Section 8.6 of the EIP and approved by the Compensation Committee of the Board of Directors of the Company. The number of stock options subject to each outstanding award was increased proportionately to preserve its value as a result of the Dividend. The number of stock options was increased by a factor of 1.45068 rounded down to the nearest whole option, which is a ratio of the Official Nasdaq Closing Price of $51.92 on March 1, 2012, the day immediately before the ex-dividend date, to the Official Nasdaq Opening Price of $35.79 on March 2, 2012, the ex-dividend date. The mandatory adjustments in connection with the Dividend were exempt from Section 16(b).
(4) Pursuant to Second Amended and Restated Equity Incentive Plan (EIP) and Compensation Committee action 9/27/04, grant agreement amended to provide that Vesting Schedule is: 25% on 5/1/03, 25% on 5/1/04, 25% on 5/1/05, 25% on 9/1/05.
(5) Pursuant to Second Amended and Restated Equity Incentive Plan (EIP) and Compensation Committee action 9/27/04, grant agreement amended to provide that Vesting Schedule is: 25% on 12/11/03 25% on 12/11/04 50% on 9/1/05
(6) Pursuant to Second Amended and Restated Equity Incentive Plan (EIP) and Compensation Committee action 9/27/04, grant agreement amended to provide that Vesting Schedule is: 25% on 12/11/04 75% on 9/1/05
(7) Vesting Schedule: 25% 12/10/05, 25% 12/10/06, 25% 12/10/07, 25% 12/10/08
(8) 2006 Stock Option Grant Award Vesting Schedule: 25% 12/1/07, 25% 12/1/08, 25% 12/1/09, 25% 12/1/10
(9) 2007 Stock Option Grant Award Vesting Schedule: 25% 11/30/08, 25% 11/30/09, 25% 11/30/10, 25% 11/30/11
(10) 2008 Stock Option Grant Award Vesting Schedule: 25% 12/1/2009, 25% 12/1/2010, 25% 12/1/2011, 25% 12/1/2012
(11) 2009 (FY10) Non-Qualified Stock Option Grant Vesting Schedule: 25% 12/1/2010, 25% 12/1/2011, 25% 12/1/2012, 25% 12/1/2013
(12) 2010 (FY11) Non-Qualified Stock Option Grant Award Vesting Schedule: 25% 12/1/2011, 25% 12/1/2012, 25% 12/1/2013, 25% 12/1/2014.
(13) 2011 (FY12) Non-Qualified Stock Option Grant Vesting Schedule: 25% 12/1/2012, 25% 12/1/2013, 25% 12/1/2014, 25% 12/1/2015.
(14) Required by Section 8.6 of the EIP and approved by the Compensation Committee of the Board of Directors of the Company, the exercise price of the option was proportionally adjusted on March 2, 2012 to preserve its value as a result of the leveraged recapitalization via the Dividend. The exercise price of each outstanding stock option was decreased by a factor of 0.68933 rounded up to the nearest whole cent, which is a ratio of the Official Nasdaq Opening Price of $35.79 on March 2, 2012, the ex-dividend date, to the Official Nasdaq Closing Price of $51.92 on March 1, 2012, the day immediately before the ex-dividend date. The mandatory adjustments in connection with the Dividend were exempt from Section 16(b).
(15) This option pursuant to the EIP, was previously reported by the reporting person as an option for 47,500 shares of common stock at an exercise price of $51.37.
(16) This option pursuant to the EIP, was previously reported by the reporting person as an option for 60,000 shares of common stock at an exercise price of $48.91.
(17) This option pursuant to the EIP, was previously reported by the reporting person as an option for 63,000 shares of common stock at an exercise price of $37.78.
(18) This option pursuant to the EIP, was previously reported by the reporting person as an option for 26,000 shares of common stock at an exercise price of $31.57.
(19) This option pursuant to the EIP, was previously reported by the reporting person as an option for 16,500 shares of common stock at an exercise price of $37.40.
(20) This option pursuant to the EIP, was previously reported by the reporting person as an option for 21,500 shares of common stock at an exercise price of $23.21.
(21) This option pursuant to the EIP, was previously reported by the reporting person as an option for 18,900 shares of common stock at an exercise price of $31.11.
(22) This option pursuant to the EIP, was previously reported by the reporting person as an option for 17,250 shares of common stock at an exercise price of $41.51.
(23) This option pursuant to the EIP, was previously reported by the reporting person as an option for 18,300 shares of common stock at an exercise price of $40.52.

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

Potential persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB number.