Exchange Highlights: Rise in Equities Post-Market Volumes. Options Specs Available.

Rise in Equities Post-Market Volumes. Options Specs Available.

Highlights & Recent Developments

  • MEMX exchange market share was 5.7% in February, up from 5.5% in January
  • MEMX’s post-market volume increased 76% month over month, after extending trading to 8 p.m.
  • MEMX Options will launch August 7, 2023 and technical specifications are available for download here (under Protocol Specs > Options)

Equities Update

In February, MEMX exchange market share (excludes TRF volume) was 5.7% and the exchange ranked second in the number of symbols (1,990) quoted over 75% of the time at the NBBO. MEMX ranked third in NBBO setting, accounting for 13.5% of best-priced setting instances among all exchanges.

On February 1, MEMX extended the Post-Market Trading Session from 5 p.m. to 8 p.m. EST, which contributed to a 76% month over month increase in MEMX’s post-market volume. Excluding closing auction prints, trading after 4 p.m. accounted for 4.0% of industry volume in February.

Sixty-three of the world’s largest trading firms are MEMX members, with diverse participation from global banks, market makers, and agency and retail brokers. More than 10% of MEMX add volume in February was retail, which received high fill rates of 94% for odd lots and 98% for order sizes between 100 to 9,999 shares on orders placed near the NBBO.

Options Update

As a reminder, MEMX plans to begin trading options on August 7, 2023 in a phased rollout. The new exchange will leverage the strengths of MEMX’s data-centric architecture and state-of-the-art infrastructure.


  • Specifications are available for download here (under Protocol Specs > Options)
  • Market model: Price/time
  • Fee model: Maker/taker (fees to be announced at a later date)
  • Functionality: Regular orders only (no complex or crossing orders)
  • Key Dates:
    • User Acceptance Test #1: Saturday, July 22, 2023
    • User Acceptance Test #2: Saturday, July 29, 2023
    • Launch: Monday, August 7, 2023
    • Additional Phases: Monday, August 14, 2023 and Monday, August 21, 2023
  • Industry exchange codes, and member test environment availability are pending
  • Existing members can use their existing cross connects for equities to also trade options
  • MEMX Options Rulebook (SEC-approved)
  • Membership Documents