FTX co-founder Gary Wang and former Alameda Research co-CEO Caroline Ellison both pleaded guilty to federal charges in the Southern District of New York, U.S. Attorney Damian Williams said in a message Wednesday.

Simultaneously, the Securities and Exchange Commission released a civil complaint against them both, alleging that they were involved "in a multiyear scheme to defraud equity investors in FTX, the crypto trading platform co-founded by Samuel Bankman-Fried and Wang."

Ellison was singled out in the SEC complaint for engaging in artificial manipulation of FTT, FTX's self-issued token, as part of a broader effort to boost Alameda Research's available collateral for lending.

Alameda Research was linked to multiple loans from major crypto firms that have now filed for bankruptcy protection, including Voyager Digital and BlockFi Lending.

Williams did not offer specific details on charges against Ellison or Wang. The SEC alleges that both Ellison and Wang, in their respective roles at Alameda and FTX, abetted Bankman-Fried in allegedly defrauding FTX customers.

The SEC alleges that Wang created a software backdoor in FTX's platform which allowed Alameda to divert customer funds for its own trades. Alameda was led by Bankman-Fried until 2021, when Ellison assumed control alongside Sam Trabucco, who departed from Alameda in August 2022.

Ellison, 28, and Wang, 29, become the second and third individuals to be charged in connection with FTX's multibillion-dollar collapse. Bankman-Fried, 30, was indicted in federal court earlier this month.

"Bankman-Fried and Wang thus gave Alameda and Ellison carte blanche to use FTX customer assets for Alameda's trading operations and for whatever other purposes Bankman-Fried and Ellison saw fit," the SEC said. Trabucco, who joined Alameda "in or around 2019," according to the SEC, was not mentioned in connection with any wrongdoing.

Wang's attorney said in a statement, "Gary has accepted responsibility for his actions and takes seriously his obligations as a cooperating witness."

Counsel for Ellison did not immediately respond to CNBC's request for comment. A spokesperson within the Bankman-Fried camp declined to give comment.

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— CNBC's Steven Kopack and Brian Schwartz contributed to this report.