A nuclear power plant engineering manager for Constellation Energy has been indicted on federal insider trading charges of using advance knowledge that his company planned to reopen a uranium-powered electric plant at Three Mile Island to collect illegal profits on the stock options market.
Casey Muggleston, of Marshallton, Del., worked on the license renewal team applying to the Nuclear Regulatory Commission for permits to restart the plant. According to a Delaware grand jury indictment, Muggleston made $1.48 million from his “scheme to obtain illegal profits” using “material nonpublic information” before Constellation announced its decision.
Following an investigation by FBI agents in Maryland and Delaware, Muggleston was charged Wednesday by the U.S. Attorney’s Office for Delaware with securities fraud and four counts of insider trading.
The charges carry a maximum sentence of 105 years, if he is convicted. However, white-collar sentences are typically a fraction of guideline terms. The government also wants Muggleston to forfeit the $1.48 million.
Neither Muggleston, who worked for Constellation or its former owner Exelon Corp. from 2008 until 2025, according to a related SEC complaint, or his attorney returned a call seeking comment.
“Constellation is aware of the government’s indictment,” company spokesperson Paul Adams said in an email. “As Mr. Muggleston is no longer an employee, we have no further comment.”
According to the indictment, Muggleston bought call options on the company’s shares, a cheap way to collect gains in a stock’s share value, without having to pay the shares’ entire trading cost.
Three relatives also bought options but have not been charged, according to the indictment.
In a separate the Securities & Exchange Commission alleged Muggleston also shared information on other confidential Constellation deals as late as June 2025. He left the company that year, according to the SEC.
Here’s what the indictment alleges:
As early as April 2024, Constellation had said publicly that it was looking at restarting the reactor but hadn’t made a decision. Before going public with the news, Constellation had employees such as Muggleston refer to the restart as “Project Tetris.”
A May 21 email to staff, including Muggleston, which was part of correspondence cited by both federal prosecutors and the SEC in their complaints, told employees to keep the licensing team’s progress “very confidential.”
Three days later, Muggleston sent his cousin, who lives near the plant, an email noting “the restart is building steam. I’m trying to think of how to profit off this …” He added that there were “no guarantees.”
Eight days later, on June 1, he gave the cousin a heads-up that a decision would likely be made later that month.
By June 8, Muggleston had begun buying Constellation options in his Delaware brokerage account, betting the stock would rise, mostly by dates in July or August. By Aug. 14, he had accumulated 195 options contracts.
But Constellation hadn’t announced the reopening. The share price for a time drifted lower, and some of his initial options expired and became unprofitable.
Then on Aug. 15, two colleagues told Muggleston the restart was approved, and he was summoned to a restart planning meeting.
Starting the next day, he bought another 150 options, then another 360. In early September the stock rose to over $200, making more of his options profitable.
On Sept. 20, when Constellation made its announcement, the stock closed at $255, and he sold his 550 remaining options for a total profit of $1.48 million.
Muggleston had taken Constellation’s annual training reminding employees, board members and contractors that they and their family members are barred from trading on insider information and from “tipping” outsiders with that information, the indictment says. Insider trading is also illegal under federal securities law.
The nuclear restart would help Constellation, a Baltimore-based power plant operator, supply data centers under a contract with Microsoft, among other customers. The plan is supported by President Donald Trump, Gov. Josh Shapiro and other government officials. Environmental critics say the process is being rushedand could raise the likelihood of contamination.
Constellation’s plan focuses on Three Mile Island’s reactor that closed in 2019 for economic reasons. It was not damaged in the 1979 partial nuclear meltdown.
Constellation says it’s on track to load uranium into the reactor next spring and begin to supply electric power later in 2027.
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