The U.S. Securities and Exchange Commission has named both Gemini and Genesis in a lawsuit.

In a complaint filed on Thursday, the SEC alleged that crypto lending firm Genesis and crypto exchange Gemini had conducted an unregistered offer and sale of securities to retail investors.

“Through this unregistered offering, Genesis and Gemini raised billions of dollars’ worth of crypto assets from hundreds of thousands of investors. Investigations into other securities law violations and into other entities and persons relating to the alleged misconduct are ongoing,” stated the complaint.

The unregistered offering in question relates to Gemini’s yield-bearing Earn product that it offered to investors by loaning out their deposits to Genesis. After Genesis halted withdrawals in November, following FTX’s collapse, Gemini Earn users were also unable to withdraw their crypto assets and are owed a collective amount of $900 million.

Crypto conglomerate Digital Currency Group (DCG) is the parent company of the liquidity-strapped Genesis. Gemini was founded by Cameron and Tyler Winklevoss in 2014.

In its complaint, the SEC took aim at Gemini for a 4.29% agent fee it charged on returns paid to Gemini Earn investors. The regulator also alleged that Genesis exercised discretion in how it used these investors’ assets to generate revenue.

Gemini’s Earn program, carried out through Genesis’s lending facility, should have been registered as a securities offering as per the law, stated the complaint.

The SEC is seeking permanent injunctive relief, disgorgement of ill-gotten gains and civil penalties from both Gemini and Genesis.

The lawsuit is the latest development in an ongoing battle between Genesis and Gemini which has turned increasingly ugly over the last few weeks. Earlier this month, Gemini co-founder Cameron Winklevoss accused DCG CEO Barry Silbert of “bad faith stall tactics” in working out a timely resolution for its clients, saying DCG was liable for the money owed to Genesis Earn users.

Silbert refuted Winklevoss’s claims that DCG owed Genesis money, and claimed that the firm had delivered a resolution proposal to Genesis and Gemini which had gone unanswered. In a series of tweets later that week, he said it had been challenging to have his integrity and good intentions questioned.

In a tweet on Thursday, Tyler Winklevoss said he was disappointed that the SEC had chosen to file a lawsuit against Gemini despite the Earn program being regulated by the New York Department of Financial Services and that Gemini had been in discussions with the SEC about the Earn product for 17 months.