Cryptocurrency derivatives exchange BitMEX started investigating “unusual activity” after users reported a momentary fall in the Bitcoin (BTC) spot price on the platform.

At around 1 am UTC, users on X reported an anomaly in BitMEX’s BTC/Tether spot market that temporarily brought down Bitcoin prices to roughly $8,900.

Reportedly, an unknown entity sold over 400 BTC in a short period of time. BitMEX confirmed the large sell order on the BTC/USDT spot market and began investigating the situation internally.

BitMEX said that its derivatives markets and the prices of the XBT derivatives contracts were not affected by the fluctuation.

According to crypto researcher Syq, the unknown whale sold roughly over 400 BTC in batches of 10–50 BTC over two hours. The researcher also revealed that BitMEX had disabled the withdrawals from some accounts.

In response to the blocked accounts, BitMEX said:

“Just to clarify: We have NOT disabled withdrawals for all users, but only for a few accounts that are part of the investigation.”

BitMEX also confirmed that its trading platform is operating normally and all funds are safe.

BitMEX has yet to respond to Cointelegraph’s request for comment.

Related: Spot Bitcoin ETFs could ‘completely destroy’ Bitcoin: Arthur Hayes

The former CEO of BitMEX, Arthur Hayes, previously opined that the spot Bitcoin exchange-traded funds (ETFs) could “completely destroy” Bitcoin if they are too successful.

According to Hayes, Bitcoin ETF issuers holding all the BTC would negatively impact the number of transactions on the Bitcoin network, and miners will lose any incentive to keep validating transactions.

“The end result is miners turn off their machines as they can no longer pay for the energy required to run them,” said Hayes. “Without the miners, the network dies, and Bitcoin vanishes.”

Magazine: South Africa’s digital-nomad crypto hub: Cape Town, Crypto City Guide