Japanese regulators may consider rule changes to make it easier for alternative stock markets to compete with a merged Tokyo Stock Exchange Group Inc. and Osaka Securities Exchange Co.

SBI Japannext, Chi-X Japan Ltd. and other new venues that display prices handled 5 percent of the trades in Topix stocks last year, the most since the platforms started in 2007. Still, the growth lagged behind similar venues in Europe and Canada because of rules that treat the platforms differently than traditional bourses, according to Deutsche Bank AG and Nomura Holdings Inc.

"Proprietary trading systems serve an important market function," said Kosuke Yokoo, director for collective investment schemes at the Financial Services Agency. "We don't currently have plans to change the rules, but we'll monitor the situation surrounding the PTS, including looking at growth and the impact of the TSE-OSE merger on the market."