EMERSON ELECTRIC CO — Director's Dealing 2006

Apr 25, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2006-04-21

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
2006-04-21	Common Stock	S	15000	$24.2383	Disposed	7251711	Indirect
2006-04-24	Common Stock	S	15000	$24.1183	Disposed	7236711	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 21, 2006, as follows: 1,600 shares at $24.00;
200 at $24.14; 100 at $24.15; 230 at $24.17; 2,200 at $24.18; 270 at $24.19; 1,701 at $24.20; 800 at $24.21; 600 at $24.22;
100 at $24.24; 899 at $24.25; 700 at $24.26; 1,274 at $24.27; 600 at $24.28; 126 at $24.29; 200 at $24.30; 400 at $24.31;
594 at $24.38; 106 at $24.39; 1,200 at $24.40; 200 at $24.41; 100 at $24.42; 200 at $24.43; 100 at $24.44; 200 at $24.46;
100 at $24.47; and 200 at $24.51. The weighted average sales price for these transactions was $24.2383 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 April 24, 2006, as follows and as described in
Footnote 4 below: 200 shares at $23.87; 200 at $23.91; 400 at $23.92; 200 at $23.93; 200 at $23.95; 500 at $23.96; 800 at
$23.97; 300 at $23.99; 600 at $24.00; 800 at $24.01; 500 at $24.02; 400 at $24.03; 200 at $24.04; 400 at $24.05; 200 at
$24.06; 400 at $24.07; 400 at $24.08; 200 at $24.09; 200 at $24.10; 200 at $24.11; 200 at $24.12; 200 at $24.13; and 400 at
$24.14.

F4: This footnote sets forth additional detail with respect to the transactions described in Footnote 3, as follows: 400 shares
at $24.16; 192 at $24.17; 300 at $24.18; 408 at $24.19; 100 at $24.20; 800 at $24.21; 200 at $24.22; 500 at $24.23; 800 at
$24.24; 1,400 at $24.25; 300 at $24.26; 600 at $24.27; 200 at $24.28; 200 at $24.29; 300 at $24.30; and 200 at $24.32. The
weighted average sales price for these transactions was $24.1183 per share.

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