On Thursday, a class action lawsuit was filed in a California district court alleging that employees of the popular cryptocurrency exchange Coinbase engaged in insider trading of Bitcoin Cash.

The class action lawsuit was filed by cryptocurrency trader Jeffery Berk on behalf of himself and other traders who claim to have suffered monetary damages as a result of the alleged insider trading at Coinbase.The amount in damages the plaintiffs are seeking is not included in the documents and will be decided in court.

On December 19, Coinbase made a surprise announcement that it had started to trade a cryptocurrency called Bitcoin Cash. Coinbase has more customers than the mainstream finance company Charles Schwab, so its decision on whether to support a cryptocurrency has a big impact on that cryptocurrency’s value. Indeed, within minutes of Coinbase’s announcement, the price of Bitcoin Cash shot up by nearly $1,000 and all further Bitcoin Cash trades were cancelled.

Berk is alleging that he and everyone else who wasn’t aware of Coinbase’s decision to begin supporting Bitcoin Cash got screwed over by those who were privy to that info ahead of the announcement. A Coinbase spokesperson told me the company is aware of the lawsuit and is currently reviewing the claims.

A graph showing the price of Bitcoin Cash from December 18, 2017 to December 21, 2017, the period cited in the lawsuit. The red arrow marks the time when Coinbase announced it had begun trading Bitcoin Cash to the public. Image: Coinmarketcap.com

According to Berk, insiders were able to flood GDAX—a trading platform owned by Coinbase—with Bitcoin Cash buy and sell orders immediately after the announcement went public. Only minutes after Coinbase announced it would start trading Bitcoin Cash, Coinbase cited liquidity issues and stopped all further trades and cancelled existing orders. It wasn’t until the following day that other Coinbase customers were able to place their Bitcoin Cash orders.

“When Coinbase’s customers’ trades were finally executed, it was only after the insiders had driven up the price of Bitcoin Cash, and thus the remaining Bitcoin customers only received their Bitcoin Cash at artificially inflated prices that had been manipulated well beyond the fair market value of Bitcoin Cash at that time,” Berk’s lawsuit reads.

In the lawsuit, Berk claims to have placed an order for Bitcoin Cash only five minutes after Coinbase announced it had begun supporting the cryptocurrency on December 19. Berk’s order wasn’t filled until a day later, however, during which time the price of Bitcoin Cash experienced a wild price spike. By the time Berk’s order was filled, he was paying $4,200 for Bitcoin Cash, roughly twice the price when he placed his order.

Bitcoin Cash is a hard fork of the original Bitcoin that was created last August. Bitcoin Cash differentiates itself from the original Bitcoin by allowing more transactions to be included in each block of the Bitcoin blockchain.

Anyone holding Bitcoin at the time of the hard fork received the same amount in Bitcoin Cash. The problem was that if anyone’s bitcoins were held in an exchange that didn’t support the Bitcoin Cash hard fork, they wouldn’t be able to access their Bitcoin Cash after the hard fork. Originally, Coinbase said it didn’t plan on supporting Bitcoin Cash and that if users wanted to claim their Bitcoin Cash they would have to withdraw their bitcoins from the exchange before the fork.

Only two days after the fork, however, Coinbase and its trading platform, GDAX, announced it would in fact be supporting Bitcoin Cash. At the time, Coinbase didn’t give a hard timeframe for when it would start supporting the fork, saying only that it was planning to support Bitcoin Cash by January 1.

Then things started to get hairy.

On December 19, Coinbase announced it had opened access to Bitcoin Cash for trading in a tweet. There were no prior announcements indicating that Coinbase intended to open up Bitcoin Cash trading on that day prior to the tweet. In the hours before and directly after the announcement, the price of Bitcoin Cash began to skyrocket to over $3,400, almost double the previous day’s price.

Accusations of insider trading prompted Coinbase CEO Brian Armstrong to write a post the following day describing trading policies for employees at Coinbase. According to Armstrong, “all Coinbase employees and contractors were explicitly prohibited from trading Bitcoin Cash and from disclosing our launch plans over a month ago.” Armstrong also said the company would be conducting an investigation into insider trading among Coinbase employees.