EMERSON ELECTRIC CO — Director's Dealing 2006

May 3, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2006-05-01

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
2006-05-01	Common Stock	S	45336	$23.4904	Disposed	7141375	Indirect
2006-05-02	Common Stock	S	56822	$23.4456	Disposed	7084553	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 1, 2006, as follows and as described in Footnotes
2 and 3 below: 300 shares at $22.97; 100 at $22.99; 2,700 at $23.00; 100 at $23.01; 800 at $23.02; 2,400 at $23.03; 1,000 at
$23.04; 300 at $23.05; 300 at $23.06; 100 at $23.07; 100 at $23.11; 200 at $23.13; 500 at $23.14; 200 at $23.15; 131 at
$23.16; 400 at $23.18; 700 at $23.20; 200 at $23.21; 227 at $23.22; 400 at $23.23; 400 at $23.24; 100 at $23.25; 200 at
$23.26; 100 at $23.28; 100 at $23.29; 200 at $23.30; 300 at $23.31; 1,100 at $23.32; 200 at $23.33; 377 at $23.34; 100 at
$23.36; 400 at $23.37; 800 at $23.38; 1,100 at $23.39; and 1,000 at $23.40.

F2: This footnote sets forth additional detail with respect to the transactions described in Footnote 1, as follows: 500 shares
at $23.41; 300 at $23.42; 100 at $23.44; 700 at $23.45; 700 at $23.46; 200 at $23.47; 600 at $23.50; 800 at $23.51; 300 at
$23.52; 300 at $23.53; 100 at $23.54; 500 at $23.55; 400 at $23.56; 600 at $23.57; 313 at $23.58; 637 at $23.59; 189 at
$23.60; 1,195 at $23.61; 900 at $23.62; 800 at $23.63; 610 at $23.64; 1,092 at $23.65; 1,055 at $23.66; 700 at $23.67; 600
at $23.68; and 400 at $23.69.

F3: This footnote sets forth additional detail with respect to the transactions described in Footnote 1, as follows: 1,495
shares at $23.70; 300 at $23.71; 500 at $23.72; 500 at $23.73; 500 at $23.74; 1,000 at $23.75; 200 at $23.76; 400 at $23.77;
500 at $23.78; 400 at $23.79; 300 at $23.80; 200 at $23.81; 400 at $23.82; 200 at $23.83; 200 at $23.84; 700 at $23.85; 500
at $23.86; 665 at $23.88; 683 at $23.89; 309 at $23.90; 700 at $23.91; 58 at $23.92; 100 at $23.93; 500 at $23.94; 700 at
$23.95; 300 at $23.96; 200 at $23.98; 400 at $24.00; 100 at $24.01; and 100 at $24.04. The weighted average sales price for
these transactions was $23.4904 per share.

F4: The reported securities are owned directly by Astec America Inc. The Reporting Person is the ultimate parent company of
Astec America Inc.

F5: The sales were effected in multiple transactions, at varying prices, on May 2, 2006, as follows and as described in Footnote
6 below: 700 shares at $22.88; 100 at $22.89; 200 at $22.90; 300 at $22.91; 100 at $23.10; 200 at $23.12; 400 at $23.13; 700
at $23.14; 200 at $23.15; 400 at $23.16; 300 at $23.18; 100 at $23.19; 100 at $23.20; 200 at $23.21; 300 at $23.22; 100 at
$23.23; 144 at $23.24; 500 at $23.25; 200 at $23.26; 400 at $23.27; 300 at $23.28; 300 at $23.29; 700 at $23.30; 1,400 at
$23.31; 1,400 at $23.32; 1,800 at $23.33; 900 at $23.34; 1,500 at $23.35; 900 at $23.36; 500 at $23.37; 700 at $23.38; 800
at $23.39; and 1,200 at $23.40.

F6: This footnote sets forth additional detail with respect to the transactions described in Footnote 5, as follows: 1,619
shares at $23.41; 2,400 at $23.42; 2,302 at $23.43; 6,079 at $23.44; 1,100 at $23.45; 300 at $23.46; 1,547 at $23.47; 2,700
at $23.48; 1,500 at $23.49; 2,600 at $23.50; 300 at $23.51; 143 at $23.52; 200 at $23.53; 200 at $23.54; 400 at $23.55; 700
at $23.56; 600 at $23.57; 1,500 at $23.58; 1,000 at $23.59; 1,510 at $23.60; 1,804 at $23.61; 786 at $23.62; 1,247 at
$23.63; 800 at $23.64; 268 at $23.65; 700 at $23.66; 673 at $23.67; 1,300 at $23.68; 1,700 at $23.69; 400 at $23.70; 369 at
$23.71; and 31 at $23.72. The weighted average sales price for these transactions was $23.4456 per share.

F7: The reported securities are owned directly by Emerson Electric Co.