In November 2023, the Electricity System Operator (ESO) published its assessment and conclusions of Phase 4 of its Net Zero Market Reform (NZMR) programme. The NZMR was initiated back in 2021 to present and contribute to the ESO’s perspective on holistic market design and supporting investment policy for net zero, and contribute to the Review of Electricity Market Arrangements (REMA) debate. Phase 4 focuses on assessing investment policies and their packaging with wholesale market reforms. Within the report, while the ESO upholds the principle that wholesale market signals remain the foundation for efficient operation and investment, there is recognition that additional investment policy support remains critical to accelerate and de-risk the investment needed to achieve net zero. Following the report, the ESO notes that it will continue to analyse wholesale market design, investment policy options, and market reform packages. This will be used, alongside stakeholder feedback, to respond to the next REMA consultation.