The deregulation of the Proprietary Trading Systems (PTS) industry started in 2011 when the Japan Securities Clearing Corporation was opened to the PTS venues.
The next step was the removal of the takeover bid rule
(TOB rule or 5% rule) to increase competitiveness of PTSs.
Originally, the rule required investors to start a tender offer when their position in a listed company was approaching five per cent.
The rule had a side effect: traders were wary of inadvertently breaking the rule and were trading less aggressively.
The removal brings PTSs to the same terms with JPX bourses.