EMERSON ELECTRIC CO — Director's Dealing 2006

May 30, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2006-05-26

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
2006-05-26	Common Stock	S	42998	$20.6672	Disposed	6446350	Indirect

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	1065182	Direct

Footnotes

F1: The sales were effected in multiple transactions, at varying prices, on May 26, 2006, as follows and as described in Footnote
2 below: 100 shares at $20.00; 100 at $20.25; 300 at $20.26; 300 at $20.31; 200 at $20.35; 100 at $20.36; 300 at $20.38;
100 at $20.40; 200 at $20.42; 100 at $20.44; 200 at $20.45; 298 at $20.48; 2 at $20.49; 399 at $20.50; 700 at $20.52; 500 at
$20.53; 300 at $20.54; 1,383 at $20.55; 3,993 at $20.56; 3,324 at $20.57; 100 at $20.58; 3,100 at $20.59; 1,105 at $20.60;
2,976 at $20.61; 600 at $20.62; 100 at $20.63; 400 at $20.64; and 1,500 at $20.65.

F2: This footnote sets forth additional detail with respect to the transactions described in Footnote 1, as follows: 1,100
shares at $20.66; 1,400 at $20.67; 400 at $20.69; 800 at $20.70; 900 at $20.72; 100 at $20.73; 500 at $20.75; 1,090 at
$20.76; 1,610 at $20.77; 1,908 at $20.78; 1,049 at $20.79; 851 at $20.80; 300 at $20.81; 1,800 at $20.82; 800 at $20.83; 300
at $20.84; 403 at $20.85; 897 at $20.86; 1,800 at $20.87; 910 at $20.88; 300 at $20.89; 600 at $20.90; 100 at $20.92; 200 at
$20.93; and 100 at $20.94. The weighted average sales price for these transactions was $20.6672 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.