X0303 4 2010-01-04 0001072343 ARCH CHEMICALS INC ARJ 0001183718 WETMORE DOUGLAS J C/O ARCH CHEMICALS, INC. 501 MERRITT 7 NORWALK CT 06851 1 0 0 0 Phantom Stock Units 2010-01-04 4 A 0 6203.267 A Common Stock 6203.267 23733.275 D The security converts to common stock on a one-for-one basis. Phantom Shares of Common Stock are credited periodically to a deferred stock account under the Arch Chemicals, Inc. 1999 Stock Plan for Non-Employee Directors ("Directors Stock Plan") and are settled in common stock or cash following the date the reporting person ceases to be a director in a transaction exempt under 16b-3. This particular grant settles in cash except as otherwise provided in the Directors Stock Plan. Dividend equivalents are also credited periodically to the reporting person's stock account under the Directors Stock Plan. These dividend equivalents are exempt from reporting under Rule 16a-11 in accordance with SEC advice. Total figure includes these dividend equivalents, if any. Joseph P. Lacerenza, Attorney in Fact 2010-01-05