EMERSON ELECTRIC CO — Director's Dealing 2006

Feb 27, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2006-02-23

Reporting Person: EMERSON ELECTRIC CO (10% Owner)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2006-02-23	Common Stock	S	35000	$22.6713	Disposed	8339736	Indirect
2006-02-24	Common Stock	S	69283	$22.4924	Disposed	8270453	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 35,000 shares on February 23, 2006. In the discretion of the broker, the sales were effected in multiple
transactions, at varying prices, on February 23, 2006, as follows and as described in Footnote 2 below: 781 shares at
$22.42; 106 at $22.43; 181 at $22.44; 500 at $22.49; 100 at $22.50; 100 at $22.51; 100 at $22.53; 800 at $22.54; 800 at
$22.55; 500 at $22.56; 1,000 at $22.57; 400 at $22.58; 300 at $22.59; 1,300 at $22.60; 1,100 at $22.61; 800 at $22.62; 1,700
at $22.63; 1,200 at $22.64; 1,900 at $22.65; 1,400 at $22.66; 1,400 at $22.67; and 1,600 at $22.68.

F2: This footnote sets forth additional detail with respect to the transactions described in Footnote 1, as follows: 1,900 shares
at $22.69; 1,400 at $22.70; 1,400 at $22.71; 632 at $22.72; 1,672 at $22.73; 1,900 at $22.74; 3,600 at $22.75; 1,328 at
$22.76; 900 at $22.77; 500 at $22.78; 900 at $22.79; 300 at $22.80; 200 at $22.84; and 300 at $22.88. The weighted average
sales price for these transactions was $22.6713 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 69,283 shares on February 24, 2006. In the discretion of the broker, the sales weres effected in multiple
transactions, at varying prices, on February 24, 2006, as follows: 100 shares at $22.42; 100 at $22.43; 9,150 at $22.45;
1,850 at $22.46; 11,200 at $22.47; 3,800 at $22.48; 19,400 at $22.49; 4,600 at $22.50; 3,079 at $22.51; 5,321 at $22.52;
3,405 at $22.53; 2,000 at $22.54; 2,700 at $22.55; 1,100 at $22.56; and 1,478 at $22.57. The weighted average sales price
for these transactions was $22.4924 per share.

F5: The reported securities are owned directly by Emerson Electric Co.