Coinbase is facing a new lawsuit alleging that its employees and other insiders reaped huge gains by trading on nonpublic information that the cryptocurrency exchange planned to support transactions in a Bitcoin offshoot called Bitcoin Cash.

The class action suit, filed Thursday in the U.S. District Court for the Northern District of California, appears to be the first filed in a federal court alleging insider trading-like claims over Coinbase's announcement that it would handle transactions in Bitcoin Cash last December.

According to the complaint, insiders drove up the price of Bitcoin Cash, also called BCH, by executing buy and sell orders moments after the move by Coinbase—one of the largest cryptocurrency exchanges in the world.

The activity caused the value of the cryptocurrency to spike by 200 percent in the minutes after trading opened on Dec. 19, the complaint adds. That led Coinbase to temporarily freeze trading, and remaining Bitcoin Cash purchasers were forced to pay “artificially inflated prices that had been manipulated well beyond the fair market value of BCH at that time,” it alleges.

The complaint also says that, while Coinbase CEO Brian Armstrong has publicly acknowledged suspicions of insider trading and pledged to undertake an internal investigation, “to date, neither Armstrong nor the company has disclosed the result of its purported investigation.”

The complaint was filed by Green & Noblin in Larkspur, California, and by The Grant Law Firm in New York. The named plaintiff, Jeffrey Berk, is an Arizona resident who alleges that his buy order for BCH was executed at roughly double the price as when he submitted it.

Coinbase did not immediately respond to an email seeking comment about the lawsuit.

Although the complaint makes insider trading-like allegations, it cites California's Unfair Competition Law and common law negligence as causes of action—likely due to the fact that BCH is not currently regulated as a security. The Commodities Futures Trading Corp. has said that Bitcoin is a commodity.

BCH was created last year by what is known as a “hard fork” of the Bitcoin blockchain—the creation of a variant of the original software. According to the complaint, Coinbase initially suggested it would not handle transactions in BCH. The company later said it would begin supporting some transactions in BCH in January 2018 but then abruptly changed course by opening trading on Dec. 19, the complaint alleges.

In a subsequent blog post, a senior Coinbase manager wrote that employees were notified about a month ahead of time that support for trading in BCH was coming. Those employees “were explicitly prohibited from buying and selling BCH,” he added. “All employees were also barred from sharing this information with anyone outside of Coinbase.”