In a move that could take the nation's online trading boom to another level, U.S. electronic trading broker will join with Softbank Finance Corp. to launch Japan's first electronic communications network for securities trading as early as this summer.

The move signals the birth of the first U.S.-style ECN in Japan.

ECNs in the U.S. allow investors to trade securities within their networks instead of placing orders with traditional bourses. They have grown rapidly in the past few years, with experts saying ECNs now account for between 20 percent and 25 percent of all trading volume on Nasdaq.