ISO-NE has detailed proposed changes to its day-ahead ancillary services (DAAS) market to address higher-than-expected costs.
The RTO is working to expedite a series of market reforms, initially recommended by its Internal Market Monitor, intended to increase market participation and lower costs.
The NEPOOL Markets Committee heard about the proposed changes April 14. The RTO aims to implement the changes Oct. 22, subject to FERC’s approval.
The implementation of the DAAS market has led to around $1 billion in incremental costs since ISO-NE launched the market in March 2025, according to the IMM. This cost vastly exceeds the estimate included in ISO-NE’s initial impact assessment, which, based on market data from 2019 to 2021, concluded that the new market would increase costs by an average of $140 million annually.
Already elevated prices following the launch of the market were exacerbated by prolonged cold weather that led to record wholesale costs over the past winter. (See 2025/26 Most Expensive Winter in History of ISO-NE Markets.)
“Changes in market fundamentals alone do not fully explain the observed level of DAAS costs,” the IMM wrote in a February memo. “Participation has been lower, and offer prices higher, than assumed in the [impact assessment].”
While ISO-NE announced its support of three “narrowly targeted” DAAS market changes in February, New England states and consumer advocates have continued to push the RTO to act as quickly as possible.
“The unprecedented cost increases documented by the IMM are imposing substantial and unanticipated burdens on electricity consumers across New England, including those in New Hampshire, and demand urgent attention to protect ratepayers,” wrote New Hampshire Gov. Kelly Ayotte (R) in a letter to the ISO-NE board in mid-March.
The IMM’s recommendations include:
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- Increasing the strike price to more accurately reflect the short-run marginal costs of most resources participating in the market.
- Decreasing the forecast energy requirement to reflect the low levels of participation of front-of-the-meter renewables in the day-ahead market.
- Potentially reducing the non-performance factor associated with the 10-minute reserve requirement.
At the April 14 Markets Committee meeting, ISO-NE gave an overview of its proposals to implement the first two recommendations. It plans to discuss its proposal for the third recommendation at the Reliability Committee meeting on April 22, and present on estimated cost effects at the Markets Committee in May.
Increased Strike Price
In the DAAS market, the strike price is a settlement component used to determine closeout charges. When the real-time locational marginal price (LMP) exceeds the strike price, resources committed in the market receive the day-ahead reserve clearing price plus the strike price, but forgo real-time revenues associated with higher real-time prices. If a resource does not fulfill its day-ahead obligation, the difference between the strike price and the real-time LMP is a key component for determining its net settlement liability.
ISO-NE has said a lower strike price will increase resources’ opportunity costs, increasing offer prices in the DAAS market. A strike price lower than a resource’s short-run marginal costs would not increase the resource’s incentives but would increase closeout risks, potentially reducing market participation, said Ben Ewing of ISO-NE.
Increasing the strike price would have the reverse effect but generally would reduce resources’ performance incentives by lowering the financial liability associated with failing to perform, the RTO has indicated.
“Generally, setting a higher strike price value will tend to lower consumers’ costs,” said Matthew White, chief economist at ISO-NE, in testimony submitted to FERC in 2023 (ER24-275). “This is because a higher strike price value lowers sellers’ opportunity costs of acquiring day-ahead ancillary service obligations. That, in turn, will tend to decrease sellers’ day-ahead ancillary service offer prices, and lower the total costs.”
In the wake of high DAAS prices, ISO-NE proposes to establish a strike price floor “based on characteristics of an efficient [combustion turbine] using the lowest-cost distillate fuel.”
Combustion turbines have received about 65% of DAAS awards cleared, while combined cycles have received about 29%. All other resources have received less than 7% of awards.
ISO-NE’s proposal is intended to increase the strike price so that it’s “better aligned with the [short-run marginal costs] of most sellers,” Ewing said. He acknowledged this change would reduce incentives for some gas-fired resources during low-load periods, but that the change should largely maintain incentives during high-load hours or periods with elevated reliability risk.
Based on historical DAAS market data, ISO-NE’s proposed methodology would lead to an average strike price floor of $141/MWh, which would increase the strike price in about 90% of hours, he said.
He added that ISO-NE analysis indicates the change would lead to a 41-47% decline in the amount of DAAS awards that retain the full incentives of the current design during low-load hours, compared to a 12-16% decline in the number of awards that receive the full incentives during high-load hours.
Forecast Energy Requirement Reduction
Under the current rules, the forecast energy requirement (FER) constraint in the DAAS market equals ISO-NE’s day-ahead energy forecast. It determines the need for energy and energy imbalance reserves, the latter of which is a new ancillary service intended to close the gap between the demand forecast and the amount of demand that clears in the day-ahead market.
ISO-NE noted that front-of-the-meter wind and solar resources consistently clear less day-ahead energy than they are forecast to produce, causing the FER to underestimate their contributions. On average, about 40% of forecast front-of-the-meter wind and solar energy clears in the day-ahead market.
“As a result, the DAM may commit additional resources or clear other forms of supply in place of [wind and solar resources] to meet the load forecast,” Ewing said. “Procuring more supply than is needed to satisfy a reliability requirement can be costly and inefficient.”
To address the issue, ISO-NE proposes to reduce the FER demand quantity by the difference between the amount of wind and solar forecast and the amount of wind and solar that clears in the day-ahead market. ISO-NE data indicate this would reduce the FER demand quantity by an average of 422 MW, Ewing said.
The change “directly addresses the inefficiency observed by the IMM,” can be made relatively quickly and will not lead to issues if renewable resources owners begin to offer a larger share of energy into the day-ahead market, he added.


