The Tokyo Stock Exchange said Tuesday it has not made any decision on the issue of tightening its rules on margin trading.
The comment followed a report by the Nihon Keizai Shimbun in its Tuesday morning edition that the world's second-largest bourse is considering tightening the rules to keep the market from overheating.
The TSE said in a written statement that it "has neither determined, nor announced" anything on the matter.
The business daily reported the TSE may stiffen margin trading rules because the popularity of online trading is boosting margin trading balances so much that the market has begun to overheat.
The report said the bourse is considering reducing the upper limit on the value of shares and other securities that an investor can put up as collateral to 70 percent of the overall collateral value, from the current 80 percent.