Internal Market Monitor issues fall 2025 report

Elevated natural gas prices drove a proportional increase in wholesale electricity costs in fall 2025, according to ISO New England’s Internal Market Monitor (IMM).

The IMM’s Fall 2025 Quarterly Markets Report, which covers the period from Sept. 1 to Nov. 30, 2025, presents an assessment of each of the region’s wholesale electricity markets, based on market data, performance criteria, and independent studies.

Key findings include:

• The total estimated wholesale market cost of electricity in fall 2025 was $1.87 billion, up 25% compared to fall 2024.
• Energy costs climbed 58% to $1.56 billion. The main driver was a 58% year-over-year increase in the price of natural gas.
• Real-time energy prices averaged $45.22 per megawatt hour (MWh), up 27% from fall 2024. Day-ahead energy prices were up 24% year over year, averaging $44.64.
• Capacity costs totaled $266 million, down 26% from the previous fall.

Included in the report is a section analyzing market performance on Nov. 23 during a reserve shortage that lasted 30 minutes. The event resulted from the unexpected loss of 900 MW of generating capability and triggered the region’s Pay-for-Performance rules.

The report also notes that New England was a net exporter of electricity during fall 2025, likely for the first time in at least 20 years. The region historically has been a net importer. The change was driven by continuing drought conditions affecting hydropower production in Canada, as well as increased nuclear and wind production within New England.