EMERSON ELECTRIC CO — Director's Dealing 2006

Apr 4, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2006-03-31

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
2006-03-31	Common Stock	S	15000	$23.4631	Disposed	7461711	Indirect
2006-04-03	Common Stock	S	15000	$23.5076	Disposed	7446711	Indirect

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	1065182	Direct

Footnotes

F1: The sales were effected in multiple transactions, at varying prices, on March 31, 2006, as follows: 100 shares at $23.18; 200
at $23.21; 200 at $23.24; 100 at $23.27; 400 at $23.29; 200 at $23.30; 100 at $23.33; 300 at $23.38; 100 at $23.40; 500 at
$23.41; 964 at $23.42; 200 at $23.43; 600 at $23.44; 700 at $23.45; 706 at $23.46; 800 at $23.47; 1,600 at $23.48; 1,900 at
$23.49; 1,730 at $23.50; 700 at $23.51; 1,300 at $23.52; 700 at $23.53; 300 at $23.54; 100 at $23.55; 300 at $23.56; 100 at
$23.57; and 100 at $23.63. The weighted average sales price for these transactions was $23.4631 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 3, 2006, as follows and as described in
Footnote 4 below: 100 shares at $23.27; 500 at $23.28; 700 at $23.29; 400 at $23.30; 100 at $23.31; 100 at $23.32; 200 at
$23.34; 100 at $23.35; 300 at $23.38; 100 at $23.40; 500 at $23.41; 300 at $23.42; 100 at $23.43; 17 at $23.44; 100 at
$23.45; 700 at $23.46; 500 at $23.47; 400 at $23.48; 1,600 at $23.49; 1,113 at $23.50; 13 at $23.51; 600 at $23.52; 200 at
$23.53; and 400 at $23.54.

F4: This footnote sets forth additional detail with respect to the transactions described in Footnote 3, as follows: 700 shares
at $23.56; 100 at $23.57; 500 at $23.58; 100 at $23.59; 1,100 at $23.60; 300 at $23.61; 900 at $23.62; 600 at $23.63; 300 at
$23.65; 400 at $23.66; 57 at $23.67; 200 at $23.68; 100 at $23.69; 100 at $23.70; 200 at $23.74; and 200 at $23.75. The
weighted average sales price for these transactions was $23.5076 per share.

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