| Jul. 1999 |
Sumitomo Metal Industries, Ltd., Mitsubishi Materials Corp., and Mitsubishi Materials Silicon Corp. established a jointly-owned company for the development and manufacturing of 300 mm silicon wafers, named Silicon United Manufacturing Corp. |
| Feb. 2002 |
Silicon United Manufacturing Corp. acquired the silicon wafer business (Sitix Division) from Sumitomo Metal Industries, Ltd., merged with Mitsubishi Materials Silicon Corp., and changed its corporate name to Sumitomo Mitsubishi Silicon Corp. |
| Aug. 2005 |
Changed corporate name to SUMCO CORPORATION |
| Nov. 2005 |
Listed on the First Section of the Tokyo Stock Exchange |
| Oct. 2006 |
Komatsu Electronic Metals Co., Ltd. (now SUMCO TECHXIV CORPORATION) became a consolidated subsidiary through a tender offer. |
| Mar. 2023 |
High-Purity Silicon Corporation became a subsidiary through stock acquisition. |
