The chaos created by Mizuho Securities Co.'s mistaken attempt to sell 610,000 shares of J-Com stock for 1 yen apiece deepened Friday as it was learned that the Tokyo Stock Exchange is trying to prevent the brokerage from reneging on the transaction, TSE officials said Friday.

One possible step is to set a certain price for a J-Com share that is higher than the investors' purchasing price and to forcibly settle the deal by paying investors in cash, according to bourse sources.

The exchange fears there are about 100,000 shares that Mizuho Securities will be unable to hand over to purchasers to settle the transaction, and is considering the forcible settlement measure -- the first such action in 55 years -- to preserve trust in the stock market.