Bain Partners, General Atlantic and Kohlberg Kravis are among those interested in purchasing a stake in Semiconductor Manufacturing International Corp (SMIC), China's largest chipmaker. The private equity firms are willing to spend about US$600 million for 20-25% of the Shanghai-based company, the South China Morning Post reported. However, SMIC is extending the completion deadline, originally set for the end of the month, in the hope of attracting interest from the likes of TPG-Newbridge and Blackstone Group. "They want to engage two, ideally three investors, so no single investor has too much control," a source said. However, the insistence of SMIC CEO Richard Chang Ru-gin that he retain full management control of the firm is seen by some as an obstacle to a deal being reached.