EMERSON ELECTRIC CO — Director's Dealing 2006

Apr 13, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2006-04-12

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
2006-04-12	Common Stock	S	15000	$22.9536	Disposed	7341711	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 12, 2006, as follows: 100 shares at $22.79; 100
at $22.80; 100 at $22.83; 500 at $22.84; 200 at $22.85; 200 at $22.86; 300 at $22.87; 209 at $22.88; 500 at $22.89; 800 at
$22.90; 883 at $22.91; 800 at $22.92; 900 at $22.93; 1,500 at $22.94; 800 at $22.95; 1,300 at $22.96; 500 at $22.97; 1,400
at $22.98; 200 at $22.99; 800 at $23.00; 708 at $23.01; 400 at $23.02; 700 at $23.05; 400 at $23.06; 200 at $23.07; 300 at
$23.08; 100 at $23.09; and 100 at $23.11. The weighted average sales price for these transactions was $22.9536 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 reported securities are owned directly by Emerson Electric Co.