EMERSON ELECTRIC CO — Director's Dealing 2006

Mar 13, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2006-03-09

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
2006-03-09	Common Stock	S	30332	$21.9149	Disposed	7909957	Indirect
2006-03-10	Common Stock	S	23246	$21.9982	Disposed	7886711	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 30,332 shares on March 9, 2006. In the discretion of the broker, the sales were effected in multiple transactions,
at varying prices, on March 9, 2006, as follows and as described in Footnote 2 below: 100 shares at $21.68; 400 at $21.70;
300 at $21.71; 500 at $21.72; 1,200 at $21.73; 200 at $21.74; 603 at $21.75; 400 at $21.76; 1,000 at $21.77; 800 at $21.78;
900 at $21.79; 800 at $21.80; 400 at $21.81; 630 at $21.82; 500 at $21.83; 1,600 at $21.84; 700 at $21.85; 1,700 at $21.86;
2,399 at $21.87; 1,884 at $21.88; 508 at $21.89; 808 at $21.90; 800 at $21.91; 385 at $21.94; 1,715 at $21.95; 400 at
$21.96; 200 at $21.97; and 500 at $21.99.

F2: This footnote sets forth additional detail with respect to the transactions described in Footnote 1, as follows: 100 shares
at $22.00; 100 at $22.01; 100 at $22.02; 200 at $22.03; 100 at $22.04; 400 at $22.05; 100 at $22.06; 700 at $22.07; 100 at
$22.08; 900 at $22.09; 1,000 at $22.10; 611 at $22.11; 100 at $22.12; 389 at $22.13; 300 at $22.14; 1,500 at $22.15; 200 at
$22.16; 300 at $22.17; 300 at $22.20; 200 at $22.21; 100 at $22.22; and 200 at $22.25. The weighted average sales price for
these transactions was $21.9149 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 23,246 shares on March 10, 2006. In the discretion of the broker, the sales were effected in multiple
transactions, at varying prices, on March 10, 2006, as follows and as described in Footnote 5 below: 100 shares at $21.57;
300 at $21.60; 100 at $21.65; 100 at $21.66; 300 at $21.74; 600 at $21.75; 100 at $21.76; 100 at $21.77; 100 at $21.78; 100
at $21.79; 100 at $21.81; 200 at $21.82; 100 at $21.84; 100 at $21.86; 200 at $21.88; 759 at $21.89; 541 at $21.90; 301 at
$21.91; 200 at $21.92; 400 at $21.93; 100 at $21.94; 200 at $21.97; 200 at $21.98 and 100 at $21.99.

F5: This footnote sets forth additional detail with respect to the transactions described in Footnote 4, as follows: 3,600 shares
at $22.00; 2,200 at $22.01; 500 at $22.02; 1,000 at $22.03; 1,054 at $22.04; 946 at $22.05; 1,800 at $22.06; 2,545 at
$22.07; 500 at $22.08; 1,700 at $22.09; 1,500 at $22.10; 300 at $22.12; and 200 at $22.13. The weighted average sales price
for these transactions was $21.9982 per share.

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