A number of brokers provide a dark pool service, where a pair of buy and sell orders is reported without pre-trade transparency to ToSTNeT, in order to minimize the market impact risk for institutional investors. Dark pool services for retail investors also exist for the purpose of price improvement.

Kai-X (“Cboe Kai-X” as the full name) is a dark pool service with the similar mechanism as the others but the direct participants are broker dealers registered in Japan. Kai-X receives orders from the brokers and finds the other side of order. When Kai-X finds a match, it immediately sends an indication of the match to the corresponding broker and at the same time each broker sends the order to ToSTNet for TSE off-auction execution. For the brokers using Kai-X, additional liquidity from the other brokers can be easily sourced. Kai-X works as an outsourced facility for brokers who do not have their own darkpool.

Market structures and rules listed below includes excerpts from the Market Guide. Please see the Market Guide listed under Document Library in Get Connected Page.

Stock Universe

TSE-primary listed common stocks, ETFs and REITs (excluding foreign stocks and foreign ETFs). Trading units used in TSE are applied

Service Hours

9:00~11:30, 12:30~15:00 (JST) on business days (same as TSE)

Trading Rules

Kai-X is an intermediary service in which Cboe Japan receives and matches orders from participants systematically. Orders are continuously matched, and after a match Kai-X notifies the respective information necessary for the participant to report to ToSTNeT with minimal delay.
The following 3 price points are available for orders.

Limit price can be set. Day, IOC, FOK are available as Time in Force.

Tick size is 0.01 yen with the exception of those with Lot size of 1 and 10, of which the tick size is 1 yen and 0.1 yen.

Minimum Execution Quantity

If an order is specified to have a Minimum Quantity, matching of the order will only occur when there is another order with enough quantity on the opposite side to fulfill the MQ

Risk Control

The checks below are performed at order entry at Kai-X.

Size Limit Check Limit of maximum number of lots per order(set by participant)
Notional Limit Check Limit of maximum value per order(set by participant)


In addition, the following risk control functions are available on demand.


Cancel on Disconnect All open orders from a given session will be cancelled when the session disconnects.
Cancel on ToSTNeT Failure All open orders and matched orders pending ToSTNeT confirmation for a given participant will be cancelled if the participant’s ToSTNeT session disconnected, or if an order submitted to ToSTNeT timed out
Dropcopy Real-time copy of messages including order acknowledgements/trades are available for participants for their own risk management
Self Trade Prevention Orders tagged with the same identifier submitted by the same participant or the same end-client will not be matched
Kill Switch A participant can use this service to stop order submission on their FIX sessions and ToSTNeT session used in the Supplemental Service

Trading participants (as of February 2022)

BNP Paribas Securities Japan
Credit Suisse Securities (Japan)
Mitsubishi UFJ Morgan Stanley Securities
Morgan Stanley MUFG Securities
Okasan Securities
Rakuten Securities

(Alphabetical Order)