The Shanghai Composite Index (SCI) ended Tuesday within touching distance of the 4,000-point mark as China's markets resumed trading following the week-long Labor Day break. The SCI posted a 2.8% gain to finish at a record 3,950.01 as the combined daily turnover of the Shanghai and Shenzhen markets hit US$41 billion, the second-highest ever, the Wall Street Journal reported. The index has risen 24% since the end of March, 48% since the start of 2007 and 240% since the regulators started the market restructuring process two years ago. Individual investors have opened more than 10 million trading accounts so far this year. The 4,000 mark has inevitably drawn attention to what many describe as a bubble in the market that is just waiting to be corrected. When the SCI passed 3,000 in late February, a mass sell-off ensued and the market plunged 8.8%. However, the opposite happened last November when the 2,000 mark was reached.