EMERSON ELECTRIC CO — Director's Dealing 2006

Mar 23, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2006-03-21

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
2006-03-21	Common Stock	S	15000	$22.7031	Disposed	7581711	Indirect
2006-03-22	Common Stock	S	15000	$22.4759	Disposed	7566711	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 21, 2006, as follows and as described in
Footnote 2 below: 300 shares at $22.34; 200 at $22.35; 100 at $22.37; 200 at $22.38; 100 at $22.39; 700 at $22.40; 100 at
$22.41; 100 at $22.46; 200 at $22.51; 600 at $22.52; 100 at $22.54; 200 at $22.60; 300 at $22.62; 200 at $22.63; 2,000 at
$22.64; 900 at $22.65; 500 at $22.66; 100 at $22.67; 300 at $22.68; 500 at $22.69; 2,100 at $22.70; 100 at $22.72; 200 at
$22.74; 300 at $22.75; and 200 at $22.76.

F2: This footnote sets forth additional detail with respect to the transactions described in Footnote 1, as follows: 400 shares
at $22.77; 200 at $22.78; 100 at $22.79; 100 at $22.83; 200 at $22.86; 100 at $22.87; 385 at $22.88; 15 at $22.89; 200 at
$22.90; 100 at $22.91; 100 at $22.93; 400 at $22.94; 200 at $22.95; 300 at $22.97; 500 at $22.99; 600 at $23.00; and 500 at
$23.05. The weighted average sales price for these transactions was $22.7031 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 March 22, 2006, as follows and as described in
Footnote 5 below: 100 shares at $22.30; 200 at $22.31; 100 at $22.33; 100 at $22.34; 200 at $22.36; 200 at $22.37; 300 at
$22.38; 500 at $22.39; 1,200 at $22.40; 429 at $22.41; 400 at $22.42; 471 at $22.43; 800 at $22.44; 1,000 at $22.45; 1,300
at $22.46; 500 at $22.47; 500 at $22.48; 700 at $22.49; 500 at $22.50; 700 at $22.51; 900 at $22.52; 600 at $22.53; 900 at
$22.54; 392 at $22.55; and 502 at $22.56.

F5: This footnote sets forth additional detail with respect to the transactions described in Footnote 4, as follows: 600 shares
at $22.57; 100 at $22.58; 100 at $22.59; 200 at $22.61; 100 at $22.63; 400 at $22.64; and 6 at $22.65. The weighted average
sales price for these transactions was $22.4759 per share.

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