Gemini, a crypto platform, paid high interest rates to ordinary Americans for nearly two years.
In November, Cameron and Tyler Winklevoss' 340,000 programme customers were unable to withdraw their money.
The Securities and Exchange Commission (SEC) is currently looking into ways to remedy the situation.
On Thursday, the regulator charged Gemini and Genesis with not registering their programme as a security.
It holds firms accountable and may create damages to repay investors.
The SEC is targeting Gemini Earn, a crypto account scheme that guaranteed high-interest returns
Thus, Gemini Earn has frozen $900 million with no indication of when clients can get it.