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Market Sessions

The AEX market operates on a daily session cycle. Each day the market moves through a fixed sequence of states — from closed overnight, through a pre-open staging window, to a live trading session, and back to closed at the end of the day. Understanding these states tells you what you can do at any given time and what will happen to your orders when the state changes.

Session states​

StateLabel in UIDescription
closedCLOSEDNo trading activity. Order submission and matching are suspended. You can view historical data but cannot place or modify orders.
preopenPRE-OPENYou can submit, modify, and cancel orders. Matching does not occur. An Indicative Opening Price (IOP) is broadcast so you can see where the market is likely to open.
openOPENFull trading is active. Orders can be submitted, modified, cancelled, and will match against resting counterparty orders.
suspendedSUSPENDEDThe market has been halted by an operator. Matching is paused. Order submission is suspended. This state persists until an operator resumes the market.

Daily schedule​

The session cycle follows a configurable schedule in the Pacific/Auckland timezone. A typical trading day runs:

  1. Closed — overnight and outside trading hours
  2. Pre-open — a window before market open (configurable start time, e.g. 07:30)
  3. Open — live trading (configurable start time, e.g. 08:00)
  4. Closed — end of trading day (configurable close time, e.g. 17:00)

The exact times are configured per market by the exchange operator. Check the status bar for the current session schedule.

note

All session times are based on the Pacific/Auckland timezone (New Zealand Standard Time / New Zealand Daylight Time). If you are connecting from a different timezone, ensure your local time conversion accounts for NZ daylight saving.

What you can do in each state​

Closed​

  • View your order blotter and fill history
  • View market data (last-traded prices, historical data)
  • You cannot submit, modify, or cancel orders

Pre-open​

  • Submit new orders (including held orders)
  • Modify or cancel existing orders
  • View the Indicative Opening Price (IOP) — a real-time estimate of where the market will clear at open, calculated from the current order book
  • Held orders do not participate in IOP calculation
tip

Pre-open is the ideal time to stage your opening orders. Submit them as held if you want to review before releasing, or submit them live to see their effect on the IOP immediately.

Open​

  • Submit, modify, and cancel orders
  • Orders match immediately if a counterparty order is available at an acceptable price
  • Fills are generated in real time
  • The IOP is no longer broadcast once the market is open

Suspended​

  • No order submission or matching
  • Your existing orders remain on the book but are frozen
  • The market will resume when an operator lifts the suspension
  • Only users with the Market.Operate permission can halt or resume the market

Status bar​

The Status Bar at the bottom of the screen provides a live view of the current session state.

It contains:

State label The current session state in uppercase (e.g. CLOSED, PRE-OPEN, OPEN, SUSPENDED), colour-coded:

  • CLOSED — grey
  • PRE-OPEN — amber
  • OPEN — green
  • SUSPENDED — red

Session progress bar A segmented bar representing the trading day from pre-open start to market close. The bar has two visible segments — the pre-open window (amber) and the open window (green). A moving marker shows your current position within the day.

Countdown timer The time remaining until the next state change, counting down in real time (e.g. 14:23 means 14 minutes and 23 seconds until the next transition).

Next state hint An arrow and label showing what state comes next (e.g. → OPEN or → CLOSED).

Market halt and resume​

An operator with the Market.Operate permission can halt the market at any time. When the market is halted:

  • The session state changes to suspended
  • Matching stops immediately
  • Order submission and modification are blocked
  • All existing orders remain intact on the book

When the operator resumes the market:

  • The session returns to the state it was in before the halt (e.g. if halted during open, it resumes as open)
  • Matching restarts
  • Any missed state transitions that were due while the market was halted are replayed in sequence

Missed transitions​

If the scheduled transition time passes while the market is suspended — for example, the configured close time arrives while the market is still halted — the platform queues those transitions. When the operator resumes the market, the engine replays them in order.

Example: The market is halted at 16:45 during the open session. The configured close time of 17:00 passes. When the operator resumes at 17:10, the engine immediately applies the open → closed transition, expiring GFD orders and running the session-close process.

caution

If you have live orders when the market is halted, they will remain on the book in a frozen state. When the market resumes, those orders are immediately eligible for matching again. Ensure your order prices are still valid before the market resumes.

Next steps​