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Dark pools and off-exchange trading (about half of US volume)
Over 50% off-exchange in 2025· Institution or agency
Fact, law or dataA rule, statute, definition or measured number.
Private trading systems that do not show orders before trades execute; with retail wholesalers, off-exchange trading is now about half of US share volume.
See it on the Money & Finance map →How it works
Dark pools are alternative trading systems (ATSs) run by banks and brokers under the SEC's Regulation ATS (1998). Big investors use them to trade large blocks without tipping off the market. Dark pools handle under a fifth of off-exchange volume, about a tenth of all trading; wholesalers filling retail orders from their own inventory handle most of the rest. Off-exchange trading reached about 50.6% of US share volume in 2025, the first full year above half. Trades are reported publicly right after they happen.
Why it matters
Hiding orders can cut big investors' trading costs, but if too much volume leaves lit exchanges, public prices may become less informative.
Facts, rules and data
Cboe and Rosenblatt market-share data, FINRA trade-reporting statistics, SEC Form ATS-N disclosures, and enforcement cases such as Barclays' $70 million settlement in 2016.
Debates and risks
At what level off-exchange trading starts to harm price discovery; studies disagree, and regulators have set no limit.
Connections (2)
▸Dark pools and off-exchange trading (about half of US volume) now handle slightly more trading than Stock exchanges: NYSE and NasdaqFact, law or data
The connection
In 2025 about 50.6% of US share volume traded off-exchange, in dark pools and with wholesalers filling retail orders, against about 49% on the more than a dozen exchanges. Off-exchange venues still price trades off exchange quotes, so lit exchanges do most of the price discovery.
When and why
US stock markets; the off-exchange share first topped half in a month in late 2024 and for a full year in 2025.
How we know
Cboe and Rosenblatt Securities data built from FINRA trade reports.
Debates and risks
Whether exchanges can win back volume, for example with new retail auctions, or regulators will step in.
▸Dark pools and off-exchange trading (about half of US volume) report their trades to FINRA: the brokers' self-regulatorFact, law or data
The connection
Dark pools are run by broker-dealers, so FINRA, the brokers' self-regulator, oversees them. Their trades must be reported to FINRA's trade reporting facilities, generally within 10 seconds, and FINRA publishes each pool's weekly volume after a short delay. FINRA and the SEC have fined pools for misleading clients.
When and why
Nationwide; FINRA's weekly dark-pool volume reports began in 2014.
How we know
FINRA rules and its OTC Transparency data, plus 2016 enforcement cases against Barclays and Credit Suisse.
Debates and risks
Whether delayed reporting gives enough transparency to judge dark pools' effect on prices.