EMERSON ELECTRIC CO — Director's Dealing 2006

May 26, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2006-05-24

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
2006-05-24	Common Stock	S	24479	$20.1959	Disposed	6526910	Indirect
2006-05-25	Common Stock	S	37562	$20.1592	Disposed	6489348	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 24, 2006, as follows and as described in Footnote
2 below: 2,600 shares at $20.00; 300 at $20.01; 900 at $20.02; 990 at $20.03; 700 at $20.04; 210 at $20.05; 400 at $20.06;
500 at $20.07; 300 at $20.09; 694 at $20.10; 900 at $20.11; 800 at $20.13; 1,200 at $20.14; 600 at $20.15; 500 at $20.16;
400 at $20.17; 600 at $20.18; 500 at $20.19; 800 at $20.20; 400 at $20.21; 200 at $20.22; 500 at $20.23; 1,200 at $20.24;
300 at $20.25; 700 at $20.26; 600 at $20.27; 100 at $20.28; 300 at $20.29; and 600 at $20.30.

F2: This footnote sets forth additional detail with respect to the transactions described in Footnote 1, as follows: 300 shares
at $20.31; 400 at $20.32; 700 at $20.33; 100 at $20.35; 100 at $20.36; 200 at $20.37; 1,200 at $20.38; 300 at $20.39; 200 at
$20.41; 110 at $20.42; 200 at $20.43; 100 at $20.44; 200 at $20.45; 200 at $20.46; 100 at $20.47; 200 at $20.48; 100 at
$20.49; 175 at $20.51; 100 at $20.52; 200 at $20.54; 200 at $20.55; 200 at $20.56; and 100 at $20.59. The weighted average
sales price for these transactions was $20.1959 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 25, 2006, as follows and as described in Footnote
5 below: 5,200 shares at $20.00; 1,400 at $20.01; 500 at $20.02; 600 at $20.03; 500 at $20.04; 1,200 at $20.05; 1,000 at
$20.06; 1,300 at $20.07; 1,000 at $20.08; 1,000 at $20.09; 1,400 at $20.10; 500 at $20.11; 1,000 at $20.12; 780 at $20.13;
1,000 at $20.14; 820 at $20.15; 1,000 at $20.16; 600 at $20.17; 500 at $20.18; 2,300 at $20.19; 400 at $20.20; 400 at
$20.21; 300 at $20.22; 1,900 at $20.23; 800 at $20.24; 1,300 at $20.25; 1,400 at $20.26; 700 at $20.27; 500 at $20.28; 800
at $20.29; and 536 at $20.30.

F5: This footnote sets forth additional detail with respect to the transactions described in Footnote 4 as follows: 426 shares
at $20.31; 800 at $20.32; 100 at $20.33; 600 at $20.34; 300 at $20.35; 300 at $20.36; 1,200 at $20.37; 100 at $20.38; 300 at
$20.39; 100 at $20.40; 200 at $20.41; 100 at $20.45; 100 at $20.46; 100 at $20.49; and 200 at $20.50. The weighted average
sales price for these transactions was $20.1592 per share.

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