EMERSON ELECTRIC CO — Director's Dealing 2006

Apr 17, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2006-04-13

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
2006-04-13	Common Stock	S	15000	$23.2552	Disposed	7326711	Indirect

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	1065182	Direct

Footnotes

F1: The sales were effected in multiple transactions, at varying prices, on April 13, 2006, as follows and as described in
Footnote 2 below: 200 shares at $23.00; 600 at $23.03; 500 at $23.04; 200 at $23.06; 400 at $23.08; 200 at $23.09; 300 at
$23.10; 300 at $23.12; 200 at $23.13; 1,000 at $23.14; 200 at $23.16; 100 at $23.17; 500 at $23.18; 681 at $23.19; 500 at
$23.20; 600 at $23.22; 100 at $23.23; 200 at $23.24; 600 at $23.25; 200 at $23.26; 97 at $23.27; 400 at $23.28; 200 at
$23.29; and 300 at $23.30.

F2: This footnote sets forth additional detail with respect to the transactions described in Footnote 1, as follows: 100 shares
at $23.31; 400 at $23.32; 400 at $23.33; 1,418 at $23.34; 700 at $23.35; 600 at $23.36; 500 at $23.37; 100 at $23.38; 300 at
$23.39; 305 at $23.40; 300 at $23.41; 200 at $23.42; 100 at $23.43; 400 at $23.45; 100 at $23.46; 99 at $23.49; 100 at
$23.52; 100 at $23.54; and 200 at $23.55. The weighted average sales price for these transactions was $23.2552 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 reported securities are owned directly by Emerson Electric Co.