Some Ameren Illinois customers in central and southern Illinois will soon see credits on their electricity bills following a $38 million settlement reached by Attorney General Kwame Raoul’s office with Dynegy Inc., a subsidiary of Vistra Corporation. The settlement, approved by the Federal Energy Regulatory Commission (FERC) in August 2025, concludes a decade-long investigation and litigation related to alleged market manipulation during a 2015 electricity capacity auction.
The dispute centered on the Midcontinent Independent System Operator (MISO) auction in 2015, which resulted in capacity prices for central and southern Illinois that were 40 times higher than other MISO zones and nearly nine times higher than the previous year. At the time, Dynegy had recently acquired several Ameren power plants, giving it significant influence over pricing.
“Dynegy manipulated the market to overcharge electric customers by taking advantage of rules that have already been deemed unjust and unreasonable,” Raoul said. “I am pleased that FERC has finally approved this settlement and that consumers will receive this long-overdue relief.”
Approximately $33.5 million from the settlement will be distributed as one-time credits to Ameren residential and small commercial customers who are on Basic Generation Service or Real Time Pricing supply rates. The credits will be based on individual energy usage and are expected to appear starting in December.
The Attorney General’s office filed complaints with FERC in 2015 alongside Public Citizen, Southwestern Electric Cooperative, and the Illinois Industrial Energy Consumers. They argued that Dynegy’s actions led to excessive charges for consumers due to unchecked market power. While FERC initially referred the matter for further review, it later dismissed findings of market manipulation without additional investigation.
However, after an appeal by complainants, the United States Court of Appeals reversed FERC’s dismissal and ordered further proceedings due to what it described as “starkly anomalous results” that caused capacity charges in Illinois to jump from $16.75 to $150.00. In 2024, FERC directed Dynegy to negotiate a settlement with affected parties.
Beyond refunds for Ameren customers, the agreement allocates $1.14 million for Southwest Electric Cooperative, $1.33 million for the Illinois Municipal Electric Agency, and $2 million for members of the Illinois Industrial Energy Consumers. Customers who obtain electricity through independent suppliers or municipalities are not eligible for these refunds since they did not pay inflated prices.
Bureau Chief Susan L. Satter and Senior Assistant Attorney General Scott Metzger from Raoul’s Public Utilities Bureau managed the case.