EMERSON ELECTRIC CO — Director's Dealing 2006

Mar 17, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2006-03-15

Reporting Person: EMERSON ELECTRIC CO (10% Owner)
Reporting Person: ASTEC AMERICA INC (10% Owner)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2006-03-15	Common Stock	S	15000	$23.0407	Disposed	7641711	Indirect
2006-03-16	Common Stock	S	15000	$22.8462	Disposed	7626711	Indirect

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	1065182	Direct

Footnotes

F1: The sales were effected in multiple transactions, at varying prices, on March 15, 2006, as follows: 200 shares at $22.86; 100
at $22.89; 300 at $22.90; 400 at $22.91; 500 at $22.93; 100 at $22.94; 600 at $22.95; 400 at $22.96; 700 at $22.97; 999 at
$22.98; 700 at $22.99; 1,300 at $23.00; 400 at $23.01; 700 at $23.02; 1,000 at $23.03; 500 at $23.04; 800 at $23.05; 200 at
$23.06; 100 at $23.07; 100 at $23.08; 1,400 at $23.09; 1,100 at $23.10; 500 at $23.11; 200 at $23.12; 300 at $23.13; 200 at
$23.21; 100 at $23.24; 200 at $23.25; 401 at $23.26; 100 at $23.27; 200 at $23.28; and 200 at $23.29. The weighted average
sales price for these transactions was $23.0407 per share.

F2: The reported securities are owned directly by Astec America Inc. The Reporting Person is the ultimate parent company of
Astec America Inc.

F3: The sales were effected in multiple transactions, at varying prices, on March 16, 2006, as follows and as described in
Footnote 4 below: 600 shares at $22.57; 2,100 at $22.58; 420 at $22.59; 200 at $22.60; 100 at $22.61; 200 at $22.73; 516 at
$22.74; 100 at $22.75; 500 at $22.76; 200 at $22.77; 100 at $22.78; 400 at $22.79; 300 at $22.80; 1,000 at $22.81; 500 at
$22.82; 500 at $22.83; 300 at $22.84; 452 at $22.85; 200 at $22.86; 200 at $22.87; 200 at $22.88; 200 at $22.90; 1,000 at
$22.95; 100 at $22.98; and 300 at $22.99.

F4: This footnote sets forth additional detail with respect to the transactions described in Footnote 3, as follows:100 shares at
$23.00; 500 at $23.01; 534 at $23.02; 100 at $23.03; 978 at $23.04; 300 at $23.05; 300 at $23.06; 200 at $23.10; 300 at
$23.13; 500 at $23.14; 200 at $23.15; 200 at $23.16; and 100 at $23.22. The weighted average sales price for these
transactions was $22.8462 per share.

F5: The reported securities are owned directly by Emerson Electric Co.