$580 Million Stock Swap Merger of Equals in the Semiconductor Industry

March 21, 2005

Cleary Gottlieb is representing Citigroup Global Markets   as financial advisor to Mykrolis Corp. in connection with the merger-of-equals transaction between Mykrolis and Entegris, Inc.  Under the terms of the merger, which is valued at $580 million, Mykrolis shareholders will receive 1.39 shares of Entegris common stock for each Mykrolis share.

The combined company, which will be known as Entegris, Inc., will have trailing annual sales of more than $650 million.  The combined company is expected to be the global leader in materials integrity management, which includes purifying, protecting and transporting critical materials, such as liquids, gases, wafers and other components used in the semiconductor, microelectronics and other high-technology industries.