EMERSON ELECTRIC CO — Director's Dealing 2006

Mar 29, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2006-03-27

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
2006-03-27	Common Stock	S	15000	$23.4291	Disposed	7521711	Indirect
2006-03-28	Common Stock	S	15000	$23.3474	Disposed	7506711	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 27, 2006, as follows and as described in
Footnote 2 below: 300 shares at $23.21; 100 at $23.22; 100 at $23.23; 100 at $23.24; 400 at $23.27; 200 at $23.28; 100 at
$23.29; 900 at $23.30; 200 at $23.31; 200 at $23.32; 100 at $23.33; 200 at $23.34; 100 at $23.38; 700 at $23.40; 867 at
$23.41; 1,007 at $23.42; 1,374 at $23.43; 1,442 at $23.44; and 879 at $23.45.

F2: This footnote sets forth additional detail with respect to the transactions described in Footnote 1, as follows: 1,185
shares at $23.46; 500 at $23.47; 500 at $23.48; 546 at $23.49; 400 at $23.50; 200 at $23.52; 800 at $23.53; 500 at $23.54;
500 at $23.55; 500 at $23.56; and 100 at $23.57. The weighted average sales price for these transactions was $23.4291 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 28 2006, as follows and as described in
Footnote 5 below: 1,294 shares at $23.20; 200 at $23.21; 902 at $23.22; 100 at $23.23; 600 at $23.24; 1,854 at $23.25; 300
at $23.26; 700 at $23.27; 100 at $23.28; 100 at $23.29; 900 at $23.30; 1,200 at $23.31; 400 at $23.32; 197 at $23.33; 500 at
$23.34; 100 at $23.35; 200 at $23.36; 200 at $23.37; 200 at $23.38; 500 at $23.39; and 100 at $23.40.

F5: This footnote sets forth additional detail with respect to the transactions described in Footnote 4, as follows: 200 shares
at $23.42; 474 at $23.45; 700 at $23.46; 200 at $23.47; 200 at $23.49; 300 at $23.50; 500 at $23.51; 100 at $23.52; 100 at
$23.55; 1,300 at $23.59; 100 at $23.60; and 179 at $23.61. The weighted average sales price for these transactions was
$23.3474 per share.

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