Crypto futures exchange BitMex has been sued for $300 million by an early investor under the charge of fraud, Bloomberg reported on Thursday.

The lawsuit was brought in by Frank Amato and RGB Coin, who claimed to be the first seed investor of the crypto exchange. In 2015, Amato invested $30,000 in BitMex, which, according to the agreement, were to be converted into equity.

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However, the lawsuit alleged that the founders of the exchange defaulted on the agreement, and Amato is yet to receive any equity, which per the current valuation of the company would be around $50 million. BitMex is estimated to be valued at $1 billion.

The seed investor is seeking $50 million of the value of his equities, along with another $250 million as punitive damages.

The suit was filed against the Seychelles-registered exchange on December 4 at a California state superior court in San Francisco.

A controversial mammoth in the crypto world

BitMEX is one of the largest crypto derivatives platforms, onboarding traders, mostly from Asia. It is known for offering leverage up to 100x for its futures contracts, which is welcomed by the trading community but harshly criticized by others.

According to its website, the platform handled $1.83 billion worth of trades in the last 24 hours, while the volume for the last 30 days touched $73.8 billion. Despite being large figures, they are significantly lower than the numbers reported by the exchanges months before.

Earlier this year, another Bloomberg report revealed that the exchange was under investigation of the United States Commodities and Futures Trading Commission (CFTC) for violating regulations by offering services in the country. However, neither party confirmed the allegations.

Meanwhile, the futures exchange was involved in a massive controversy recently when it accidentally leaked the personal emails of a number of its customers.