Summary of CABOT MICROELECTRONICS CORP

Item 1.01 Entry into a Material Definitive Agreement.

On December 19, 2008, Cabot Microelectronics Corporation (the "Company") announced it had entered into a definitive agreement to acquire the shares of Epoch Material Co., Ltd. ("Epoch"), a consolidated subsidiary of Eternal Chemical Co., Ltd. ("Eternal"). Under the agreement, Cabot Microelectronics will acquire the stock of Epoch for a total purchase price of USD$66 million, which the Company intends to pay in cash from its available cash. The completion of the transaction is subject to customary closing conditions and regulatory approvals. Under the share purchase agreement, Cabot Microelectronics will initially pay for and obtain 90 percent of Epoch's stock upon closing, with the remainder to be transferred and paid for eighteen months later. During this interim period, Eternal will hold a minority ownership interest in Epoch.

Epoch is a Taiwan-based company specializing in the development, manufacture and sale of copper chemical mechanical planarization ("CMP") slurries and CMP cleaning solutions to the semiconductor industry, and color filter slurries to the liquid crystal display ("LCD") industry.

A copy of the press release issued by the Company on December 19, 2008, entitled "Cabot Microelectronics Corporation Announces Agreement to Acquire Epoch Material Co., Ltd.", is attached hereto as Exhibit 99.1 and incorporated herein by reference. The Company will host a conference call to discuss the acquisition on December 19, 2008 at 10:00 a.m. Central Time.

This Form 8-K and its attachment contain forward-looking statements that involve risks and uncertainties concerning Cabot Microelectronics Corporation's acquisition of Epoch Material Co., Ltd., our expected financial performance, and our strategic and operational plans. Actual events or results may differ materially from those described in this Form 8-K and attachment due to a number of risks and uncertainties. The potential risks and uncertainties include, among others, the possibility that the transaction will not close or that the closing may be delayed; the reaction of customers of Cabot Microelectronics Corporation and Epoch to the transaction; our ability to successfully integrate Epoch's operations and employees; our ability to maintain, develop and grow Epoch's business after the closing and to realize the expected benefits of the acquisition; and general economic and business conditions. In addition, please refer to our Annual Report on Form 10-K for the fiscal year ended September 30, 2008, for a list of additional Risk Factors that may affect our business and operational results and the transaction referred to herein. Cabot Microelectronics Corporation and Epoch are under no duty to update of the forward-looking statements after the date of this Form 8-K to conform to actual results.