EMERSON ELECTRIC CO — Director's Dealing 2006

Mar 1, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2006-02-27

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
2006-02-27	Common Stock	S	45193	$22.6115	Disposed	8225260	Indirect
2006-02-28	Common Stock	S	36695	$22.4934	Disposed	8188565	Indirect

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	1065182	Direct

Footnotes

F1: The Reporting Person gave a sell order to the broker to sell shares of MKS Instruments, Inc. common stock which resulted in
sales of 45,193 shares on February 27, 2006. In the discretion of the broker, the sales were effected in multiple
transactions, at varying prices, on February 27, 2006, as follows and as described in Footnote 2 below: 100 shares at
$22.35; 100 at $22.39; 200 at $22.40; 171 at $22.41; 229 at $22.43; 100 at $22.44; 300 at $22.45; 800 at $22.47; 1,100 at
$22.48; 1,300 at $22.49; 1,100 at $22.50; 600 at $22.51; 3,181 at $22.52; 2,500 at $22.53; 3,019 at $22.54; 976 at $22.55;
400 at $22.56; 2,600 at $22.57; 2,400 at $22.58; 906 at $22.59; 921 at $22.60; and 900 at $22.61.

F2: This footnote sets forth additional detail with respect to the transactions described in Footnote 1, as follows: 939 shares
at $22.62; 1,060 at $22.63; 2,600 at $22.64; 2,100 at $22.65; 1,000 at $22.66; 500 at $22.67; 1,800 at $22.68; 991 at
$22.69; 300 at $22.70; 1,025 at $22.71; 2,975 at $22.72; 800 at $22.73; 500 at $22.74; 1,200 at $22.75; 600 at $22.76; 500
at $22.77; 1,200 at $22.78; 600 at $22.79; 200 at $22.80; and 400 at $22.82. The weighted average sales price for these
transactions was $22.6115 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 Reporting Person gave a sell order to the broker to sell shares of MKS Instruments, Inc. common stock which resulted in
sales of 36,695 shares on February 28, 2006. In the discretion of the broker, the sales weres effected in multiple
transactions, at varying prices, on February 28, 2006, as follows and as described in Footnote 5 below: 200 shares at
$22.10; 300 at $22.11; 400 at $22.12; 500 at $22.15; 1 at $22.17; 200 at $22.18; 99 at $22.19; 100 at $22.20; 1 at $22.21;
500 at $22.22; 299 at $22.23; 100 at $22.25; 200 at $22.27; 400 at $22.29; 500 at $22.31; 200 at $22.33; 100 at $22.34; 500
at $22.35; 398 at $22.36; 600 at $22.37; 302 at $22.38; 900 at $22.39; 450 at $22.40; 2,900 at $22.41; 1,920 at $22.42; 500
at $22.43; 1,100 at $22.44; 1,000 at $22.45; and 2,100 at $22.46.

F5: This footnote sets forth additional detail with respect to the transactions described in Footnote 4, as follows: 500 shares
at $22.47; 110 at $22.48; 1,030 at $22.49; 1,600 at $22.50; 900 at $22.51; 900 at $22.52; 200 at $22.53; 1,700 at $22.54;
400 at $22.55; 700 at $22.56; 300 at $22.57; 18 at $22.58; 152 at $22.59; 3,900 at $22.60; 1,300 at $22.62; 800 at $22.63;
700 at $22.64; 500 at $22.65; 200 at $22.66; 500 at $22.67; 500 at $22.68; 321 at $22.69; 500 at $22.70; 200 at $22.71; 800
at $22.72; 100 at $22.73; 100 at $22.74; 200 at $22.78; 200 at $22.83; 100 at $22.84; 200 at $22.86; and 294 at $22.88. The
weighted average sales price for these transactions was $22.4934 per share.

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