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
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(Print or Type Responses)
1. Name and Address of Reporting Person *
EMERSON ELECTRIC CO
   2. Issuer Name and Ticker or Trading Symbol
MKS INSTRUMENTS INC [MKSI] 		5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director __X__ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
(Last)
(First)
(Middle)
8000 W. FLORISSANT AVE.		 3. Date of Earliest Transaction (Month/Day/Year)
09/19/2006
(Street)

ST LOUIS, MO 63136		 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 09/19/2006   S   25,000 D $ 20.3331 (1) (2) 3,646,249 I Through a subsidiary
Common Stock 09/20/2006   S   25,000 D $ 20.8107 (3) 3,621,249 I Through a subsidiary
Common Stock               1,065,182 D  

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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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

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
EMERSON ELECTRIC CO
8000 W. FLORISSANT AVE.
ST LOUIS, MO 63136		     X    

Signatures

 /s/ Timothy G. Westman, Assistant Secretary   09/21/2006
**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) The sales were effected in multiple transactions, at varying prices, on September 19, 2006, as follows and as described in Footnote 2 below: 200 shares at $20.08; 800 at $20.12; 600 at $20.13; 100 at $20.14; 600 at $20.15; 500 at $20.16; 400 at $20.17; 1,100 at $20.18; 500 at $20.19; 700 at $20.20; 900 at $20.21; 400 at $20.22; 200 at $20.23; 200 at $20.25; 200 at $20.26; 643 at $20.27; 1,100 at $20.28; 400 at $20.29; 107 at $20.30; 400 at $20.31; 500 at $20.32; 1,000 at $20.33; 900 at $20.34; and 334 at $20.35.
(2) This footnote sets forth additional detail with respect to the transactions described in Footnote 1, as follows: 525 shares at $20.36; 1,143 at $20.37; 237 at $20.38; 500 at $20.39; 763 at $20.40; 1,400 at $20.41; 781 at $20.42; 800 at $20.43; 619 at $20.44; 1,800 at $20.45; 700 at $20.46; 500 at $20.47; 148 at $20.48; 500 at $20.50; 600 at $20.51; 200 at $20.52; 300 at $20.53; 500 at $20.54; and 200 at $20.57. The weighted average sales price for these transactions was $20.3331 per share.
(3) The sales were effected in multiple transactions, at varying prices, on September 20, 2006, as follows: 200 shares at $20.51; 200 at $20.52; 100 at $20.54; 200 at $20.56; 100 at $20.59; 100 at $20.60; 200 at $20.64; 400 at $20.65; 500 at $20.67; 1,200 at $20.68; 1,000 at $20.69; 1,323 at $20.70; 1,003 at $20.71; 600 at $20.72; 200 at $20.74; 200 at $20.75; 100 at $20.76; 600 at $20.77; 100 at $20.79; 100 at $20.81; 1,200 at $20.82; 1,000 at $20.83; 1,000 at $20.84; 2,187 at $20.85; 1,900 at $20.86; 1,301 at $20.87; 1,914 at $20.88; 1,200 at $20.89; 2,031 at $20.90; 1,096 at $20.91; 500 at $20.92; 500 at $20.93; and 745 at $20.94. The weighted average sales price for these transactions was $20.8107 per share.

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