The Shanghai Stock Exchange said yesterday it had uncovered 147 'abnormal transactions' in the first quarter, a sign the market is reinforcing house-cleaning measures. The report coincides with an increase in the number of alleged fraud and insider trading cases being prosecuted by the mainland securities regulators in recent weeks. Some of the deals led to formal investigations of stock manipulation and insider trading, the report said without giving details. It added that four companies had been censured for faulty disclosure practices and other minor irregularities. It was the first time the bourse had issued a quarterly review of its efforts to discipline the market. Previously, it had produced an annual report. About 60 per cent of listed companies, including the biggest firms, are on the Shanghai exchange. Last year, it reported 506 abnormal transaction cases with 50 investigated by the China Securities Regulatory Commission. 'The adoption of the quarterly format is intended to boost the transparency and efficiency of regulation,' said Zheng Wei, the chairman of NuWorld Investment, a mainland-based investor relations firm. 'The change comes at an interesting time with growing uncertainty in market sentiment after months of solid advances despite division over the outlook of the real economy.' The Shanghai Composite Index, which closed at 2,645.263 points yesterday, has gained more than 45 per cent so far this year. Analysts said the increased house-cleaning could be to pave the way for an array of financial products and practices that the authorities are keen to introduce to the market. These include index futures, margin trading, short selling and a Nasdaq-style second board for small and medium-sized enterprises. 'These innovations, if not properly regulated, could invite massive irregularities,' Mr Zheng said. 'Chinese regulators tend to do some ad hoc house-cleaning before they introduce new practices, partly for some sort of shock and awe effect.' Shenzhen-based Rongtong Investment Fund sacked a fund manager for alleged insider trading after the CSRC launched an investigation last month. The regulator also briefed the media last week on three cases of irregularities by firms falsifying accounts, which have already been brought to court. However, Yan Yiming, a Shanghai-based lawyer who specialises in securities fraud, was sceptical. 'Every once in a while, we see such a crackdown, but every time when the campaign runs out of steam, the dubious transactions re-emerge. There is simply no consistency.'