EMERSON ELECTRIC CO — Director's Dealing 2006

Apr 12, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2006-04-10

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
2006-04-10	Common Stock	S	15000	$22.3270	Disposed	7371711	Indirect
2006-04-11	Common Stock	S	15000	$22.7222	Disposed	7356711	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 10, 2006, as follows and as described in
Footnote 2 below: 200 shares at $22.13; 200 at $22.14; 100 at $22.15; 400 at $22.17; 400 at $22.18; 900 at $22.21; 600 at
$22.22; 100 at $22.23; 200 at $22.24; 1,700 at $22.25; 511 at $22.26; 389 at $22.27; 600 at $22.28; 900 at $22.29; 1,700 at
$22.30; 500 at $22.31; 200 at $22.32; 600 at $22.34; 400 at $22.35; 100 at $22.36; 400 at $22.38; and 200 at $22.39.

F2: This footnote sets forth additional detail with respect to the transactions described in Footnote 1, as follows: 700 shares
at $22.40; 400 at $22.41; 300 at $22.42; 400 at $22.43; 100 at $22.44; 300 at $22.45; 100 at $22.46; 200 at $22.47; 100 at
$22.50; 200 at $22.53; 400 at $22.56; 100 at $22.78; 200 at $22.80; and 200 at $22.97. The weighted average sales price for
these transactions was $22.3270 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 sales were effected in multiple transactions, at varying prices, on April 11, 2006, as follows and as described in
Footnote 5 below: 200 shares at $22.23; 200 at $22.31; 100 at $22.35; 200 at $22.37; 200 at $22.38; 100 at $22.40; 200 at
$22.41; 300 at $22.46; 100 at $22.48; 100 at $22.51; 200 at $22.54; 300 at $22.57; 200 at $22.58; 200 at $22.59; 200 at
$22.62; 200 at $22.63; 200 at $22.64; 300 at $22.67; 300 at $22.69; 646 at $22.70; 454 at $22.71; 700 at $22.72; 500 at
$22.73; 100 at $22.74; and 500 at $22.75.

F5: This footnote sets forth additional detail with respect to the transactions described in Footnote 4, as follows: 300 shares
at $22.76; 300 at $22.77; 1,200 at $22.78; 700 at $22.79; 1,313 at $22.80; 1,200 at $22.81; 600 at $22.82; 1,013 at $22.83;
400 at $22.85; 174 at $22.86; 500 at $22.87; 100 at $22.89; 100 at $22.90; 200 at $22.94; 1 at $22.95; 99 at $22.96; and 100
at $22.98. The weighted average sales price for these transactions was $22.7222 per share.

F6: The reported securities are owned directly by Emerson Electric Co.