EMERSON ELECTRIC CO — Director's Dealing 2006

Apr 27, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2006-04-25

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
2006-04-25	Common Stock	S	15000	$24.3160	Disposed	7221711	Indirect
2006-04-26	Common Stock	S	15000	$24.0333	Disposed	7206711	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 25, 2006, as follows: 987 shares at $24.30;
10,352 at $24.31; 982 at $24.32; 1,200 at $24.33; 13 at $24.34; 808 at $24.35; and 658 at $24.36. The weighted average sales
price for these transactions was $24.3160 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 26, 2006, as follows and as described in
Footnote 4 below: 100 shares at $23.51; 200 at $23.52; 400 at $23.63; 100 at $23.64; 200 at $23.65; 100 at $23.69; 95 at
$23.70; 100 at $23.77; 100 at $23.80; 200 at $23.82; 100 at $23.86; 200 at $23.90; 100 at $23.91; 300 at $23.99; 200 at
$24.01; 200 at $24.02; 877 at $24.03; and 622 at $24.04.

F4: This footnote sets forth additional detail with respect to the transactions described in Footnote 3, as follows: 1,500
shares at $24.05; 1,500 at $24.06; 1,100 at $24.07; 600 at $24.08; 1,000 at $24.09; 200 at $24.10; 1,400 at $24.11; 1,000 at
$24.12; 1,000 at $24.13; 700 at $24.14; 500 at $24.15; 300 at $24.16; and 6 at $24.17. The weighted average sales price for
these transactions was $24.0333 per share.

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