THE boom in China's stock market has led 15 mainland companies with an estimated flotation size of 750 million yuan (HK$1 billion) to seek listings on the All-China Securities Trading Automated Quotation System (STAQ), a national market trading in ''legalperson'' shares. STAQ plans to approve one or two companies a month with each company's flotation worth about 30 million yuan, according to Mr Xin Xueqing, a marketing official at the Stock Exchange Executive Council (SEEC) in Beijing, which runs STAQ. According to Mr Thomas Chan, co-ordinator of the China Business Centre at the Hongkong Polytechnic the fundamental differences between the Beijing national market (STAQ) and the regional markets in Shenzhen and Shanghai was in the different types of shares available for transaction and in the degree of access investors had to the market. STAQ deals in ''legal person'' shares, while the exchanges in Shanghai and Shenzhen deal in ''natural person'' shares. Mr Chan said: ''Legal person shares are a category of shares not found in ordinary market economies; they have been created in China. These shares are holdings in state enterprises by official bodies. ''Legal person shares are different from what are known as ''natural person'' shares, or those that can be subscribed to by individuals. ''Chinese state institutions, enterprises and departments have the status of legal person, and they are entitled to purchase natural person shares. But legal person shares cannot be sold to individual subscribers,'' he said. The establishment of STAQ has relieved pressure on the exchanges in Shenzhen and Shanghai, which are only allowed to release five billion yuan of new shares this year. ''If they [the mainland enterprises] can't list in Shanghai and Shenzhen, they can try our exchange,'' SEEC's Mr Xin said. The Chinese Government has adopted a cautious attitude towards the development of the mainland stockmarkets; the five billion yuan quota for new issues falls far short of what the market demands. STAQ is another channel for mainland enterprises that want to launch their shares to the public. But the market is restricted to trading in legal person shares. Established in October, 1990, STAQ initially traded bonds. But last year, it received the green light from Beijing to trade in legal person stocks. Since last July, the market has listed four companies; Guangxi Yuchai Machinery, Hainan Huakai Industrial, Zhuhai Hengtong Real Estate and Sichuan Shudou Mansion. Hanzhou Daziran Industrial and Shenyang Changbai Calculator Manufacturer are expected to list next month. STAQ has 160 members who can buy and sell shares for their clients through a network system linking 38 cities. It deals with 500,000 transaction a day. Mr Liu Chunlin, a researcher at SEEC, said that the trading capacity could more than double after the instalment of new and advanced facilities. He said these facilities would be available sometime this year. ''We can act as a buffer to resolve the demand from companies who want to get a public listing, and for buyers who want to invest in the stockmarket,'' said Mr Liu. ''In the past, STAQ has been used only on a trial basis. But this year, it has become a formal operation,'' he added. STAQ has more autonomy than the Shanghai and Shenzhen exchanges and the government has placed no restrictions on the size of its new issues. Although the system's operator SEEC, which began in 1989, is a private organisation, it has total influence over government policy on stock issues. The council is regarded as the think tank for the China Securities and Regulatory Committee (CSRC), the government's regulator for all securities issues. ''The CSRC will always seek the SEEC's opinion before they act, and it will always follow its view,'' said a Shanghai stock analyst. According to Mr Xin, the council originally planned to develop a third stock market instead of the STAQ system. However, the proposal was scraped after the pro-democracy crackdown in June 1989. ''We won't become the third stock market. We are the only national market in China and we believe our future looks promising,'' said Mr Xin.