Off-Exchange Flow Bifurcation

Institutional dark pools vs. retail wholesalers — H1 2025

50.2%
Off-Exchange
25.5%
Institutional ATSs
74.5%
Retail Wholesalers
Overview
Quarterly Trends
Detailed Data
Methodology

Key Finding: Within off-exchange trading, retail wholesalers account for 74.5% of volume (129.7B shares/month), nearly 3x the institutional ATS segment at 25.5% (44.3B shares/month).

Quarter Institutional ATSs Retail Wholesalers Total Off-Exchange
Q1 2025 43.7B 114.5B 158.2B
Q2 2025 44.9B 145.0B 189.9B
Segment Monthly Volume % of Off-Exchange % of Total Market
Exchange Venues
NYSE, Nasdaq, CBOE 172.9B shares — 49.8%
Off-Exchange Venues
Institutional ATSs 44.3B shares 25.5% 12.8%
Retail Wholesalers 129.7B shares 74.5% 37.4%
Subtotal Off-Exchange 174.0B shares 100% 50.2%
Total Market 346.9B shares — 100%

Competitive Focus:
Institutional ATSs: Matching precision, timing determinism, adverse-selection control
Retail Wholesalers: Price improvement, internalization efficiency on small-lot flow

Data Sources

Primary Sources: FINRA ATS Transparency Data (Tier 1 & Tier 2) and CBOE Market Statistics, H1 2025

Calculation Method

  • Institutional ATS Volume: Sum of all FINRA-registered NMS Stock Alternative Trading Systems (Tier 1 + Tier 2), excluding grand total summary rows
  • Total Off-Exchange Volume: Combined volume from FINRA/NYSE TRF, FINRA/Nasdaq TRF Carteret, and FINRA/Nasdaq TRF Chicago
  • Retail Wholesaler Volume: Calculated as (Total Off-Exchange Volume) minus (Institutional ATS Volume)
  • Period: Q1 2025 (January-March) and Q2 2025 (April-June), averaged to monthly figures

Key Finding

The 25.5% / 74.5% bifurcation reveals that retail wholesaling represents nearly 3x the volume of institutional ATS trading within off-exchange venues. These two ecosystems operate under fundamentally different competitive logics: institutional ATSs compete on matching innovation and adverse-selection control, while retail wholesalers optimize for price improvement and internalization efficiency.

Source: Author's analysis based on FINRA ATS Transparency Data and CBOE Market Statistics. All figures represent monthly averages for H1 2025 (January-June 2025).