HONG KONG will benefit from the fast-growing economy in the United States and a possible continuation of the yuan devaluation this year, an economist says. In addition, any comprehensive tightening of the mainland economy is not expected to spell doom for the territory or China itself. ''The positive factors [affecting Hong Kong's economy] are the fast growth in the US - which underlines growth in Hong Kong's exports - and the subdued inflationary pressure,'' said Ian MacFarlane, chief economist of London-based HSBC Asset Management. ''I think that we will see inflation continue to remain low because the yuan, if it keeps on depreciating, will continue to depress food prices in Hong Kong,'' he said. A significant proportion of Hong Kong's food supply comes from China. Mr MacFarlane forecasts a growth of about five per cent in the territory's gross domestic product this year, despite uncertainties on China issues. ''Against a complex backdrop of economic reform spanning the tax system, state-owned enterprises, privatisation and trade relations, the key investment questions [about Hong Kong] remains whether China will continue to overheat and if and when the authorities react to contain it,'' he said. ''My view is that there is nothing at all to worry about for this year.'' He said monetary tightening in China would not push its economy into recession because the effectiveness of such tightening measures would be limited. Changes in the real economics had rendered effective tightening difficult, he said. ''As the proportion of state-owned enterprises in the country's total output diminishes, there will be an increasingly large portion of the economy which will not be within the realm of the monetary authorities,'' Mr MacFarlane said. From nearly 80 per cent of registered output in 1979, the ratio halved to about 40 per cent last year, he said. ''The parlous condition of state-run industry and persistent political fears of social unrest suggest that there is a ceiling on the extent to which the authorities may be prepared to go,'' he said. It is estimated that nearly a third of state enterprises are bankrupt and that another third are kept afloat only by state subsidies. ''The increased autonomy given to the provinces is also likely to provide a road block to any draconian tightening, however unlikely,'' Mr MacFarlane said. China's financial reform into a freer and more competitive banking system also made the imposition of control increasingly difficult, he added. He forecast the mainland's economic growth this year to be about nine to 10 per cent, which would benefit Hong Kong's economy. On the territory's stock market, Mr MacFarlane expected a stock investment return of more than 20 per cent by the year-end. The equity market would shift its focus away from interest rates to growth prospects of fundamental earnings as the US economy was picking up to benefit Hong Kong companies. Meanwhile, the territory could expect to gain from the US-Japanese trade dispute provided it did not develop into a global trade war. ''The on-going niggling tension could revert Japanese investment into the region,'' he said.