Lonza Group, one of the world’s leading suppliers to the life science industries, announced today the expiration of the subsequent offering period of the tender offer by Lonza and its indirect, wholly-owned subsidiary LG Acquisition for all outstanding shares ofcommon stock of Arch Chemicals, at a price of $47.20 per share in cash, without interest and less any required withholding taxes.

The subsequent offering period expired at 12:00 midnight, New York City time, on Wednesday, 19 October 2011. BNY Mello Shareowner Services, the depository for the tender offer, has advised Lonza that, as of the expiration of the subsequent offering period, a total of approximately 24,395,876 shares of Arch Chemicals common stock were validly tendered and not properly withdrawn pursuant to the tender offer during the initial offering period and the subsequent offering period, representing approximately 95.9% of the outstanding shares of Arch Chemicals common stock. LG Acquisition has accepted for payment all shares validly tendered and not properly withdrawn pursuant to the tender offer during the initial offering period and the subsequent offering period.

As a result of the tenders, Lonza will own more than 90% of the outstanding shares of Arch Chemicals common stock and expects to complete its acquisition of Arch Chemicals through a short-form merger without a vote or meeting of Arch Chemicals’ shareholders. The short-form merger and completion of the acquisition of Arch Chemicals is expected to be completed no later than 21 October 2011. Upon completion of the merger, Arch Chemicals will become an indirect, wholly-owned subsidiary of Lonza. In the merger, each of the approximately 1,046,257 remaining shares of Arch Chemicals common stock not validly tendered in the tender offer will be converted into the right to receive the same $47.20 in cash per share, without interest, that was paid in the tender offer.

Lonza Microbial Control, a new business sector formed by the acquisition and led by Jeanne Thoma as previously announced, will provide customers with a complete solutions offer for their microbial control needs. The new business will be ideally positioned to increase R&D and product development spending across its broader product portfolio. Lonza will offer this complementary range of products and actives to a broader range of customers in both established and emerging markets.

Stefan Borgas, CEO of Lonza, comments: "After having built the world’s leading pharmaceutical contract manufacturer over the past years, we as of today, also are the world’s leading microbial control business. This step enhances our global footprint, balances our currencies and our business models. We have the willingness and the resources to invest in R&D and applications development for the benefit of all of our customers."

Promptly after the completion of the merger, Lonza intends to cause all shares of Arch Chemicals common stock to be delisted from the New York Stock Exchange (NYSE). Upon completion of the merger, Arch Chemicals shares will cease to be traded on the NYSE and Arch Chemicals will no longer have reporting obligations under the Securities Exchange Act of 1934, as amended.