EMERSON ELECTRIC CO — Director's Dealing 2006

May 9, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

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

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
2006-05-05	Common Stock	S	22424	$24.4016	Disposed	6977631	Indirect
2006-05-08	Common Stock	S	19507	$24.4229	Disposed	6958124	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 5, 2006, as follows and as described in Footnote
2 below: 200 shares at $24.14; 200 at $24.15; 200 at $24.16; 100 at $24.17; 100 at $24.18; 149 at $24.23; 100 at $24.24; 200
at $24.25; 100 at $24.26; 100 at $24.27; 200 at $24.28; 1,211 at $24.29; 600 at $24.30; 600 at $24.31; 500 at $24.32; 700 at
$24.33; 600 at $24.34; 1,800 at $24.35; 400 at $24.36; 1,000 at $24.37; 2,100 at $24.38; 1,300 at $24.39; 600 at $24.40; 100
at $24.41; 462 at $24.42; 200 at $24.43; 700 at $24.44; 700 at $24.45.

F2: This footnote sets forth additional detail with respect to the transactions described in Footnote 1, as follows: 200 shares
at $24.46; 200 at $24.47; 200 at $24.48; 1,000 at $24.49; 2,200 at $24.50; 1,800 at $24.51; 300 at $24.52; 100 at $24.53;
200 at $24.54; 100 at $24.55; 202 at $24.58; 200 at $24.61; 200 at $24.62; 200 at $24.63; and 100 at $24.67. The weighted
average sales price for these transactions was $24.4016 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 8, 2006, as follows and as described in Footnote
5 below: 400 shares at $24.21; 100 at $24.25; 600 at $24.26; 200 at $24.27; 200 at $24.28; 100 at $24.29; 300 at $24.30; 100
at $24.31; 200 at $24.33; 200 at $24.34; 300 at $24.35; 100 at $24.36; 900 at $24.37; 3,660 at $24.38; 740 at $24.39; 600 at
$24.40; 533 at $24.41; 700 at $24.42; 1,600 at $24.43; 700 at $24.44; and 1,290 at $24.45.

F5: This footnote sets forth additional detail with respect to the transactions described in Footnote 4, as follows: 1,100
shares at $24.46; 497 at $24.47; 1,000 at $24.48; 1,287 at $24.49; 600 at $24.50; 100 at $24.53; 100 at $24.56; 200 at
$24.57; 200 at $24.61; 100 at $24.62; 100 at $24.66; 400 at $24.68; 100 at $24.70; and 200 at $24.71. The weighted average
sales price for these transactions was $24.4229 per share.

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