Japan Exchange Group has published its monthly statistics on trading value in dark pools, with the series now running through September 2025. The dataset is the primary public record of how much Japanese equity volume executes away from the lit order book, and desks routing yen-denominated flow should treat it as the baseline for any off-venue execution review.

What does the dataset actually cover?

The series, maintained by JPX, aggregates trading value executed in dark pools — off-order-book venues where prices are not displayed before execution. That definition matters. This is not a measure of all off-exchange activity in Japan. It is a measure of the hidden-liquidity channel specifically, reported on a monthly cadence, with the current release extending to September 2025.

For buy-side desks, the practical use is simple. Compare dark pool value against total JPX cash equity turnover for the same month and you get a rough hidden-liquidity share. That ratio drives decisions on where to source block liquidity, how to set minimum fill sizes on hidden orders, and whether algorithmic strategies that probe dark venues are earning their complexity.

Why does the September 2025 cutoff matter?

The data ends at September 2025. Anyone running quarterly TCA on Japanese flow should note the boundary. October and November activity is not yet in this release. Comparisons against a benchmark built from this series will lag by a reporting cycle, and any month-over-month conclusions should be dated accordingly.

How should execution desks use it?

Three workflows benefit directly from this series:

• Venue selection. Monthly dark pool value indicates whether hidden liquidity in Japanese names is deepening or thinning. A shrinking series argues for concentrating passive block exposure in lit venues or periodic auctions.
• Cost analysis. TCA teams can pair dark pool value figures with implementation shortfall results to test whether off-venue fills actually reduced market impact, or simply shifted it.
• Broker review. Sell-side counterparties citing dark pool access in Japanese equities can be checked against the aggregate trend. Claims of capability are assertions; this series is a measurement.

What is measured versus what is asserted

The JPX release measures trading value in dark pools. It does not, in itself, measure execution quality, price improvement rates, or fill ratios. Those require desk-level data. Any vendor or broker claim that dark pool volume growth equals better outcomes for institutional flow is an assertion, not a statistic from this dataset, and should be interrogated as such.

The distinction between mandated and reported is also worth drawing. This is a market-data publication by the exchange group, not a regulatory filing. It reflects venues and flow captured within JPX's reporting framework for Japanese equities.

What comes next

JPX updates the series monthly, so desks should expect an October 2025 figure in the next release. The trend line through September 2025 — up or down — will tell flow traders whether hidden liquidity in Japanese equities is holding its share as lit-market structure evolves, and that comparison is the one worth running when the next print lands.