Stock Performance Graph The following graph illustrates the cumulative total stockholder return on our common stock during the period from September 30, 2007 through September 30, 2012 and compares it with the cumulative total return on the NASDAQ Composite Index and the Philadelphia Semiconductor Index. The comparison assumes $100 was invested on September 30, 2007 in our common stock and in each of the foregoing indices and assumes reinvestment of the special cash dividend paid in fiscal 2012. The performance shown is not necessarily indicative of future performance. See “Risk Factors” in Part I, Item 1A above. COMPARISON OF 5 YEAR CUMULATIVE TOTAL RETURN* Among Cabot Microelectronics Corporation, the NASDAQ Composite Index and the PHLX Semiconductor Index $200 180 160 140 120 100 80 60 40 20 0 9/07 12/07 3/08 6/08 9/08 12/08 3/09 6/09 9/09 12/09 3/10 6/10 9/10 12/10 3/11 6/11 9/11 12/11 3/12 6/12 9/12 Cabot Microelectronics Corporation NASDAQ Composite PHLX Semiconductor *100 invested on 9/30/07 in stock or index, including reinvestment of dividends. Fiscal year ending September 30. 9/07 Cabot Microelectronics Corporation NASDAQ Composite Philadelphia Semiconductor 12/07 3/08 75.20 80.51 87.22 9/10 6/08 77.54 81.48 90.83 12/10 9/08 75.04 69.59 77.39 3/11 12/08 60.98 56.69 61.34 6/11 3/09 56.21 53.28 67.70 9/11 6/09 66.18 64.21 74.21 12/11 9/09 81.54 74.90 90.32 3/12 12/09 77.10 79.18 96.78 6/12 3/10 88.49 82.59 94.85 9/12 100.00 84.00 100.00 96.04 100.00 95.66 6/10 Cabot Microelectronics Corporation NASDAQ Composite Philadelphia Semiconductor 80.91 73.97 86.58 75.27 96.96 122.22 108.70 80.44 110.53 129.75 97.48 117.27 84.99 93.86 99.57 98.43 86.87 94.82 108.29 105.27 110.79 91.48 110.04 110.61 112.90 100.44 111.85 132.24 120.05 127.57 19