Series

WEFT Research

Written byPolymorphic AIWEFT Research

Technical notes on NEM price spikes, measured on AEMO 5-minute data for all five regions from October 2021 to May 2026. Each note covers one property: how spikes cluster in time and spread between regions, how they escalate, how the price distribution changed between FY22 and FY26, how prices leave the daily cycle on the way to a spike, and how price risk is shared across the interconnected regions. Every figure is interactive, with a table and a method note, and results from earlier analyses are marked as such.

5Notes

12,794Spike episodes

490,7515-min intervals

5Regions

4.7 yrOct 2021 – May 2026

Note 01 · Clustering

Spike clustering and re-onset risk

A new spike follows within 30 minutes 35–49% of the time. The excess risk halves in 22–26 minutes in every region and is gone within a day.

6 figures9 min

Note 02 · Escalation

How price spikes escalate

Past $1,000, nearly half of spikes go on to $5,000, and over a third of those are there in their first interval, with no warning in the price.

· figures· min

Note 03 · Structural change

Structural change in NEM prices, FY22–FY26

Spikes fell 84% from FY22 to FY26, but the largest fell least. Negative prices became common while prices at the −$1,000 floor almost disappeared.

· figures· min

Note 04 · Geometry

The geometry of the daily price cycle

Before a spike, reserve falls for two hours while price stays calm, then price jumps; on ordinary days price turns first. High prices come in fewer, longer runs than expected.

· figures· min

Note 05 · Networks

The network structure of price risk

Prices move in a fixed order, Queensland first and South Australia last, and the ordering doubled since FY22. Pairwise couplings carry 99.3% of shared spike information.

· figures· min

Data

AEMO 5-minute regional reference prices for New South Wales, Queensland, South Australia, Tasmania and Victoria, 1 October 2021 to 31 May 2026, from the NEMWEB MMS Data Model archive. Note 04 also uses regional demand, available generation and wind output; Note 05 uses interconnector flows and limits.

Method

A spike episode is a run of consecutive 5-minute prices above $300/MWh. Rates exclude the June 2022 market suspension and administered pricing. Every figure has a Table and a Method panel.

About

WEFT Research is a series of notes from Polymorphic AI, written while building WEFT, the Wire-masked Event Forecast Transformer: a model that forecasts 5-minute prices and the onset of price spikes in Australia's National Electricity Market. See the forecast running live at WEFT live, and more of our work at polymorphic.codes.

[WEFT//NEM] · A research series by Polymorphic AI · Speak to us · prices in A$/MWh · times in market time (AEST)