EMERSON ELECTRIC CO — Director's Dealing 2006

May 15, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2006-05-11

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
2006-05-11	Common Stock	S	33403	$23.2346	Disposed	6843953	Indirect
2006-05-12	Common Stock	S	28562	$22.9572	Disposed	6815391	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 11, 2006, as follows and as described in Footnote
2 below: 100 shares at $22.74; 100 at $22.76; 100 at $22.79; 200 at $22.80; 92 at $22.81; 108 at $22.82; 200 at $22.84; 46
at $22.87; 54 at $22.89; 400 at $22.90; 100 at $22.91; 200 at $22.92; 300 at $22.93; 400 at $22.94; 300 at $22.96; 200 at
$22.97; 500 at $22.98; 73 at $22.99; 1,092 at $23.00; 100 at $23.01; 500 at $23.02; 287 at $23.03; 500 at $23.04; 800 at
$23.05; 200 at $23.06; 688 at $23.07; 800 at $23.08; 2,808 at $23.09; 608 at $23.10; 1,500 at $23.11; 1,100 at $23.12; 312
at $23.13; 200 at $23.14; and 400 at $23.15.

F2: This footnote sets forth additional detail with respect to the transactions described in Footnote 1, as follows: 800 shares
at $23.16; 400 at $23.17; 700 at $23.18; 1,700 at $23.19; 400 at $23.20; 100 at $23.21; 1,194 at $23.22; 1,400 at $23.23;
900 at $23.24; 97 at $23.25; 50 at $23.26; 300 at $23.27; 100 at $23.28; 600 at $23.29; 100 at $23.37; 500 at $23.38; 100 at
$23.39; 100 at $23.42; 400 at $23.43; 200 at $23.44; 400 at $23.46; 200 at $23.47; 200 at $23.48; 400 at $23.49; 1,000 at
$23.50; 1,000 at $23.51; 500 at $23.52; 100 at $23.54; 300 at $23.57; 200 at $23.62; 500 at $23.64; 694 at $23.66; 200 at
$23.67; 200 at $23.68; 200 at $23.69; 400 at $23.70; 200 at $23.72; 200 at $23.76; 300 at $23.79; 100 at $23.80; 100 at
$23.81; 100 at $23.82; 200 at $23.88; 100 at $23.91; and 100 at $23.92. The weighted average sales price for these
transactions was $23.2346 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 May 12, 2006, as follows and as described in Footnote
5 below: 400 shares at $22.68; 200 at $22.69; 200 at $22.70; 500 at $22.71; 200 at $22.72; 200 at $22.73; 200 at $22.74; 600
at $22.76; 300 at $22.77; 500 at $22.78; 100 at $22.79; 300 at $22.80; 900 at $22.81; 900 at $22.82; 200 at $22.83; 400 at
$22.84; 400 at $22.85; 400 at $22.86; 100 at $22.87; 600 at $22.88; 600 at $22.89; 356 at $22.90; 897 at $22.91; 800 at
$22.92; 163 at $22.93; 300 at $22.94; 2,000 at $22.95; 1,300 at $22.96; 1,900 at $22.97; 1,100 at $22.98; 500 at $22.99; and
800 at $23.00.

F5: This footnote sets forth additional detail with respect to the transactions described in Footnote 4, as follows: 500 shares
at $23.01; 500 at $23.02; 700 at $23.03; 1,292 at $23.04; 1,200 at $23.05; 241 at $23.06; 900 at $23.07; 700 at $23.08; 900
at $23.09; 600 at $23.10; 445 at $23.11; 200 at $23.12; 100 at $23.13; 95 at $23.14; 200 at $23.16; 300 at $23.17; 200 at
$23.18; 300 at $23.19; 200 at $23.20; 473 at $23.21; and 200 at $23.23. The weighted average sales price for these
transactions was $22.9572 per share.

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