EMERSON ELECTRIC CO — Director's Dealing 2006

Mar 27, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2006-03-23

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
2006-03-23	Common Stock	S	15000	$22.8484	Disposed	7551711	Indirect
2006-03-24	Common Stock	S	15000	$23.2594	Disposed	7536711	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 23, 2006, as follows and as described in
Footnote 2 below: 100 shares at $22.36; 100 at $22.37; 200 at $22.49; 100 at $22.58; 100 at $22.59; 400 at $22.60; 200 at
$22.62; 200 at $22.66; 100 at $22.69; 300 at $22.70; 300 at $22.71; 600 at $22.73; 200 at $22.74; 262 at $22.78; 1,000 at
$22.79; 638 at $22.80; 500 at $22.81; 300 at $22.82; 200 at $22.83; 500 at $22.84; 600 at $22.85; 900 at $22.86; 900 at
$22.87; 900 at $22.88; and 300 at $22.89.

F2: This footnote sets forth additional detail with respect to the transactions described in Footnote 1, as follows: 700 shares
at $22.90; 706 at $22.91; 200 at $22.92; 476 at $22.93; 300 at $22.94; 200 at $22.95; 300 at $22.96; 400 at $22.97; 200 at
$23.03; 100 at $23.05; 900 at $23.06; 300 at $23.07; 18 at $23.11; 200 at $23.14; and 100 at $23.15. The weighted average
sales price for these transactions was $22.8484 per share.

F3: The reported securities are owned directly by Astec America Inc. The Reporting Person is the ultimate parent company of
Astec America Inc.

F4: The sales were effected in multiple transactions, at varying prices, on March 24 2006, as follows and as described in
Footnote 5 below: 100 shares at $22.98; 400 at $23.00; 300 at $23.01; 500 at $23.02; 200 at $23.03; 100 at $23.06; 600 at
$23.07; 400 at $23.08; 400 at $23.10; 200 at $23.11; 100 at $23.12; 300 at $23.14; 560 at $23.15; 214 at $23.16; 86 at
$23.17; 100 at $23.18; 500 at $23.20; 200 at $23.21; 200 at $23.22; 100 at $23.23; 400 at $23.24; 800 at $23.25; 500 at
$23.26; 300 at $23.27; and 300 at $23.28.

F5: This footnote sets forth additional detail with respect to the transactions described in Footnote 4, as follows: 300 shares
at $23.29; 450 at $23.31; 400 at $23.32; 250 at $23.33; 400 at $23.35; 200 at $23.36; 630 at $23.37; 800 at $23.38; 800 at
$23.39; 200 at $23.40; 710 at $23.41; 1,200 at $23.42; 400 at $23.43; 100 at $23.44; and 300 at $23.46. The weighted average
sales price for these transactions was $23.2594 per share.

F6: The reported securities are owned directly by Emerson Electric Co.