FORMER stock exchange chairman Ronald Li Fook-shiu may have earned almost $5 million in stockmarket profits each day he spent in Stanley Prison. Li's huge stockmarket portfolio, conservatively estimated by some brokers to be worth $3 billion before his jail sentence, could have swollen to at least $7.5 billion by now if it kept pace with the Hang Seng index. The rise in the stockmarket barometer is one of the biggest changes since ''the headmaster'', as Li was known, started his jail term. On October 17, 1990, it stood at 2,949 points, on Friday it closed at 7,397, 150 per cent higher. As the man who masterminded the unification of Hongkong's four stock exchanges into a single international bourse, Li must take much of the credit for building a base for growth. Li did a ''superb job'' with the unified computerised exchange, which was a bigger success than London's, a former colleague said. For Li, a master stock-picker who once claimed he knew how to buy shares at the age of six, the paper profits in the past 32 months will have been huge. Nobody knows the true size of the Li family fortune but a list of Hongkong's top tycoons published in Capital magazine in 1988 named Li as Hongkong's third richest man with assets of $10 billion. His wealth was reportedly invested in local shares and property in North America. The share portfolio could have accounted for a third of his wealth according to investment experts. If it kept pace with the Hongkong market, one of the world's best performers over the past two years, it will have risen by an average $4.7 million for each of the 955 days he has so far spent in prison. His overseas property investments will have done less well. Recession in the United States and Canada means they may have barely increased in real value. The record stockmarket levels on the computer terminals of Hongkong brokers are not the only change Li will notice on his release on June 16. The skyline of the city has altered, with the addition of buildings such as Central Plaza, Citibank Plaza and Nine Queen's Road Central. The level of sophistication has risen too. American brokerages such as Salomons and Morgan Stanley have greatly expanded their presence to cash in on Hongkong as a play on China's opening markets. Li is said to have kept a watchful eye on the markets and his investments during his time at Stanley. One of his frequent visitors was the financial community's Legislative Council representative, Mr Chim Pui-chung, who is sure to have kept him abreast of changes. When Li went to jail, the China factor was still a drag on the stockmarket, meaning the share prices of Hongkong firms were priced at a discount. Now China is a huge plus for Hongkong's financial community. Red chip CITIC Pacific is part of the Hang Seng index and huge Chinese conglomerates are buying into the market by way of backdoor listings. As a patriotic Chinese, who often saw foreigners as interfering in the ways of Hongkong, Li would approve of China's new role. But the foreigners who came in to set up the Securities and Futures Commission have made their mark, too. The SFC was set up after the Davison report on the stockmarket collapse of 1987. One of its comments was the pre-crash exchange was run like a ''private club''. Working with the stock exchange, the SFC has helped bring in a new constitution for the stock exchange in which the international brokers have a bigger say, greater protection for small shareholders and tighter rules on disclosing information and the obligations of directors of listed companies.