Fusion Network, a blockchain-based stablecoin exchange, has announced that $6.4 million USD worth of FSN tokens have been taken from a compromised wallet.

The foundation in charge of the network revealed the theft in a blog post on Saturday, September 28. The post stated that one of the network’s wallets, containing 10 million of the Fusion Network’s native FSN tokens and 3.5 million ERC-20 FSN tokens had been emptied. The blog post went on to suggest that the theft may have been an inside job: “There is uncertain evidence showing that theft may have been caused by personnel related to the Fusion Foundation.”

“The Foundation deeply regrets this incident and its impact on the path of Fusion’s innovation,” said the firm. “While private key theft is an industry-wide risk and occurrence, we clearly must strengthen the protection around our private keys.” The theft represents nearly 25% of FSN token total market capitalization.

The Fusion Network was launched last summer with the intention of providing legacy institutions with access to blockchain by facilitating the transfer of stablecoins, coins backed against a fiat currency, and other digital coins. The Fusion Foundation, which oversees the network, is a non-profit organization based in New York headed by CEO DJ Qian, who revealed details of the FSN tokens theft via a Telegram group.

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Speaking to CoinDesk, Fusion’s Chief Product Officer John Liu said that the foundation is aware of the thief’s identity and has plans in place to demonetize the stolen FSN tokens. “This is not a newbie hacker. This criminal has been preparing this in advance. He was well prepared to implement this.” Liu added that the foundation’s method for isolating the stolen funds cannot yet be disclosed. The value of FSN tokens immediately halved following the breach, dropping from around $0.50 to $0.25 in a seven-hour period.

The news comes just a month after McAfee released its Threat Report, which pointed out that crypto-jacking was on the rise.