Thailand\'s leading stock brokers say they are concerned that huge massive money inflows could create a bubble in the stock and real estate markets. Asia Plus Securities head Kongkiat Opaswongkarn said the market index -- which went over the 1,500-point mark Thursday -- was being driven mainly by small stocks while large stocks did not have big gains, indicating speculation in the small stocks, but the country\'s finance minister said the market situation was \"natural\" and no cause for concern,\" the Bangkok Post reported Friday. Kongkiat warned of a bubble forming in the property market because of big jump in land prices in Bangkok and major provinces and urged the Bank of Thailand, Finance Ministry and commercial banks to take steps to control inflated prices without real demand. He also called for reducing margin loans or more collateral for hot stocks, the Post said. Margin loans are now set at 40 billion baht, up from 30 billion early last year. Another analyst urged investors to be cautious because of a likely correction. Finance Minister Kittiratt Na-Ranong said the current market situation was OK because the Stock Exchange of Thailand\'s SET index is driven largely by positive economic projections, the Post reported. Kittiratt, the former SET president, was quoted as saying he sees the stock market as being \"natural, given the domestic economic growth.\" The minister said regulators have effective tools to \"control fraud and manipulation in the market and stock manipulators should be very afraid.\"