Routing Fundamentals
What does MEMX routing determine when an order cannot execute internally?
Whether the order should route to an away venue or cancel, based on its order instructions.
What is the name of the entity that acts as MEMX’s Outbound Router?
MEMX Execution Services LLC.
Is routing enabled in MEMX Equities (MEE)?
Yes — live production routing
What is a routing broker?
A broker-dealer MEMX uses to access away markets for routed orders.
Where do you check first if you see a routed order reject?
The Routing tab or Deephaven logs.
What does DoNotRoute (18=6) mean?
The order is internal-only and cannot route out.
At what point in the lifecycle does routing occur?
After internal match attempt fails, before cancel/report.
Is routing enabled in MEMX Options (MOP)?
not yet but soon — routes to away options exchanges.
Who does MEMX use to route equities?
Instinet
What are the first two things you check in a routing reject scenario?
Verify symbol status and away venue connectivity.
What’s the difference between ABBO and NBBO, and which one does MEMX use for reprice logic?
NBBO = national best bid/offer; ABBO = away best bid/offer (excluding MEMX). MEMX uses ABBO for reprice logic.
What kind of checks must MEMX’s router perform before routing an order?
Credit, price band, duplication, and compliance checks (Rule 2.11(b)).
Is routing enabled in MDE or MODE?
No — test environments are internal only.
Who will MEMX use to route options?
or designated options routing broker.
What do you look for in Deephaven to debug a routing reject?
Route destination, reject reason, timestamp, and latency.
What happens to a PostOnly order when MEMX already has displayed contra liquidity at that price?
It’s canceled back — MEMX does not allow locking or crossing.
What does Rule 2.11(a)(6) empower MEMX to do during market disruption?
Cancel routed orders to maintain fair and orderly markets.
Is routing enabled for LDE (LTSE) or XDE (24X)?
No — both are isolated client test environments.
What happens when a routed order returns to MEMX unexecuted?
It’s re-entered with a new timestamp (Rule 11.11(a)(5)).
Explain the difference between internal and external rejects.
Internal rejects = MEMX logic or config; external rejects = away venue responses (e.g., Nasdaq)
Explain how BookOnly + MinQty affects routing.
The order is hidden and internal only — cannot route out due to BookOnly flag and hidden status.
According to Rule 11.11(a)(3), what are the possible outcomes for a marketable limit order after routing attempts?
It can be canceled, converted to Book-Only, or re-routed until filled.
If a member designates “Do Not Route,” which entity — MEMX or MEMX Execution Services — is responsible for handling the order?
MEMX only — the order never reaches the router.
What type of orders does MEMX route to other exchanges under Rule 11.11(a)(2)?
Market orders and marketable limit orders.
What typically causes a Nasdaq reject, and how should you respond?
Often due to unspun symbol or halt on Nasdaq. Confirm symbol spin and halt status, then escalate to Tech Ops if needed.