The Short Term Trading Market is a daily ex-ante schedule market where trading participants submit bid and offers the day prior.

Daily operations

Gas day start times

The day before

The day before the gas day (D-1), pipeline operators submit capacities for supplying the hub. Trading Participants place bids to buy gas and offers to sell gas by T+5.5 hrs.
AEMO publishes the ex-ante market schedule by T+6.5 hrs for each hub. Participants then nominate the quantity of gas they required to their pipeline operator.

On the day

On the gas day (D), the pipeline operator delivers gas to the hub and users withdraw gas at the hub.
Deviations by shippers and users are typically balanced by pipeline operators utilising the storage capacity of the transmission pipelines. The STTM primarily settles this balancing gas under AEMO’s market operator service (MOS) arrangements.

After the day

The actual quantities of gas delivered to the hub are measured daily by the pipeline operators, who, the day after the gas day (D+1), provide AEMO with the quantities that were allocated to each shipper (STTM facility allocations) on the gas day by T+4.5 hrs.
AEMO publishes the ex-post market schedule by T+5.5 hrs for each hub.

Emergency Management

Contingency gas is a market mechanism for balancing supply and withdrawals at a hub when both the ex-ante market and bilateral intraday pipeline flow variations are unable (or not expected to be able) to match supply and demand within or over a gas day.
Contingency gas provides pipeline operators and distributors with a means of avoiding, or at least minimising, the need to involuntarily curtail shippers supplying the hub or users at the hub. However, its availability or use does not imply any limit on the rights of these operators to implement involuntary curtailment.