- Statement of Changes in Beneficial Ownership (4)

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	OMB APPROVAL OMB Number: 3235-0287 Expires: November 30, 2011 Estimated average burden hours per response... 0.5
	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(f) of the Investment Company Act of 1940

1. Name and Address of Reporting Person ^* SMITH STEPHEN R	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, Marketing
(Last) (First) (Middle) C/O CABOT MICROELECTRONICS CORPORATION, 870 COMMONS DRIVE	3. Date of Earliest Transaction (MM/DD/YYYY) 3/9/2012
(Street) AURORA, IL 60504 (City) (State) (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY)	6. Individual or Joint/Group Filing (Check Applicable Line) _ X _ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. 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)
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	3/9/2012		S		5017	D	$36.124	19703	D
Common Stock	3/9/2012		M		21760	A	$34.33	41463	D
Common Stock	3/9/2012		S ⁽¹⁾		21760	D	$35.9934	19703	D

*Table II - Derivative Securities Beneficially Owned ( e.g.* , puts, calls, warrants, options, convertible securities)**
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. 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		7. Title and Amount of Securities Underlying Derivative Security (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)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)			11. Nature of Indirect Beneficial Ownership (Instr. 4)
Stock Options (Right to Buy)	$34.33 ⁽¹³⁾ ⁽¹⁵⁾	3/9/2012		M			21760	5/1/2003 ⁽²⁾	5/1/2012	Common Stock	21760 ⁽¹⁴⁾ ⁽¹⁵⁾	$ 0	0	D
Stock Options (Right to Buy)	$35.42 ⁽¹³⁾ ⁽¹⁶⁾							12/11/2003 ⁽³⁾	12/11/2012	Common Stock	82688 ⁽¹⁴⁾ ⁽¹⁶⁾		82688	D
Stock Options (Right to Buy)	$33.72 ⁽¹³⁾ ⁽¹⁷⁾							12/11/2004 ⁽⁴⁾	12/11/2013	Common Stock	87040 ⁽¹⁴⁾ ⁽¹⁷⁾		87040	D
Stock Options (Right to Buy)	$26.05 ⁽¹³⁾ ⁽¹⁸⁾							12/10/2005 ⁽⁵⁾	12/10/2014	Common Stock	78336 ⁽¹⁴⁾ ⁽¹⁸⁾		78336	D
Stock Options (Right to Buy)	$21.04 ⁽¹³⁾ ⁽¹⁹⁾							12/9/2006 ⁽⁶⁾	12/9/2015	Common Stock	19946 ⁽¹⁴⁾ ⁽¹⁹⁾		19946	D
Stock Options (Right to Buy)	$21.77 ⁽¹³⁾ ⁽²⁰⁾							12/1/2007 ⁽⁷⁾	12/1/2016	Common Stock	34816 ⁽¹⁴⁾ ⁽²⁰⁾		34816	D
Stock Options (Right to Buy)	$25.79 ⁽¹³⁾ ⁽²¹⁾							11/30/2008 ⁽⁸⁾	11/30/2017	Common Stock	23936 ⁽¹⁴⁾ ⁽²¹⁾		23936	D
Stock Options (Right to Buy)	$16 ⁽¹³⁾ ⁽²²⁾							12/1/2009 ⁽⁹⁾	12/1/2018	Common Stock	17988 ⁽¹⁴⁾ ⁽²²⁾		17988	D
Stock Options (Right to Buy)	$21.45 ⁽¹³⁾ ⁽²³⁾							12/1/2010 ⁽¹⁰⁾	12/1/2019	Common Stock	26982 ⁽¹⁴⁾ ⁽²³⁾		26982	D
Stock Options (Right to Buy)	$28.62 ⁽¹³⁾ ⁽²⁴⁾							12/1/2011 ⁽¹¹⁾	12/1/2020	Common Stock	25894 ⁽¹⁴⁾ ⁽²⁴⁾		25894	D
Stock Options (Right to Buy)	$27.94 ⁽¹³⁾ ⁽²⁵⁾							12/1/2012 ⁽¹²⁾	12/1/2021	Common Stock	25241 ⁽¹⁴⁾ ⁽²⁵⁾		25241	D

Explanation of Responses:
( 1)	Sale to cover exercise price of, and taxes related to, exercise of stock options.
( 2)	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
( 3)	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
( 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 12/11/04 75% on 9/1/05
( 5)	Vesting Schedule: 25% 12/10/05 25% 12/10/06 25% 12/10/07 25% 12/10/08
( 6)	2005 Stock Option Grant Award Vesting Schedule: 25% 12/9/2006, 25% 12/9/2007, 25% 12/9/2008, 25% 12/9/2009
( 7)	2006 Stock Option Grant Award Vesting Schedule: 25% 12/1/07, 25% 12/1/08, 25% 12/1/09, 25% 12/1/10
( 8)	2007 Stock Option Grant Award Vesting Schedule: 25% 11/30/08, 25% 11/30/09, 25% 11/30/10, 25% 11/30/11
( 9)	2008 Stock Option Grant Award Vesting Schedule: 25% 12/1/2009, 25% 12/1/2010, 25% 12/1/2011, 25% 12/1/2012
( 10)	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
( 11)	2010 (FY11) Non-Qualified Stock Option Grant Vesting Schedule: 25% 12/1/2011, 25% 12/1/2012, 25% 12/1/2013, 25% 12/1/2014.
( 12)	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.
( 13)	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).
( 14)	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).
( 15)	This option pursuant to the EIP, was previously reported by the reporting person as an option for 15,000 shares of common stock at an exercise price of $49.80.
( 16)	This option pursuant to the EIP, was previously reported by the reporting person as an option for 57,000 shares of common stock at an exercise price of $51.37.
( 17)	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.
( 18)	This option pursuant to the EIP, was previously reported by the reporting person as an option for 54,000 shares of common stock at an exercise price of $37.78.
( 19)	This option pursuant to the EIP, was previously reported by the reporting person as an option for 55,000 shares of common stock at an exercise price of $30.51.
( 20)	This option pursuant to the EIP, was previously reported by the reporting person as an option for 24,000 shares of common stock at an exercise price of $31.57.
( 21)	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.
( 22)	This option pursuant to the EIP, was previously reported by the reporting person as an option for 24,800 shares of common stock at an exercise price of $23.21.
( 23)	This option pursuant to the EIP, was previously reported by the reporting person as an option for 18,600 shares of common stock at an exercise price of $31.11.
( 24)	This option pursuant to the EIP, was previously reported by the reporting person as an option for 17,850 shares of common stock at an exercise price of $41.51.
( 25)	This option pursuant to the EIP, was previously reported by the reporting person as an option for 17,400 shares of common stock at an exercise price of $40.52.

Reporting Owners
Reporting Owner Name / Address	Relationships
Reporting Owner Name / Address	Director	10% Owner	Officer	Other
SMITH STEPHEN R C/O CABOT MICROELECTRONICS CORPORATION 870 COMMONS DRIVE AURORA, IL 60504			VP, Marketing

Signatures
/s/ H. Carol Bernstein (Power of Attorney)		3/13/2012
^** Signature of Reporting Person		Date

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
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