Australia’s National Electricity Market (NEM) commenced in 1998. The centrepiece of NEM reforms was the restructuring of vertical monopoly electricity utilities and the creation of an energy-only, gross pool wholesale market and associated forward market. For most of the past 20+ years, NEM has displayed consistent economic and technical performance. But missing policies relating to climate change, natural gas and plant exit produced results that tested political tolerance in 2016–2019. However, as with prior episodes of high prices, market participants responded—most recently—with a renewable investment supercycle. Prices have since reverted, but power system security remains challenging as the plant mix changes.