Crypto exchange and derivatives trading platform BitMEX saw bitcoin flash crash below $9,000 on its USDT spot market late Monday but had no impact on derivatives, according to the firm.

BitMEX is currently investigating “unusual activity” involving large sell orders on its BTC-USDT spot market, the exchange posted on X. “This does not affect any of our derivative markets, nor the index price for our popular XBT derivatives contracts,” it added.

“Someone just dumped 400+ BTC over 2 hours in 10-50 BTC clips on the XBTUSDT pair on Bitmex eating 30%+ slippage. They must've lost $4m+ at least,” pseudonymous crypto community member “syq” wrote. “I'm guessing that they're done (for now?). Total volume so far is just shy of 1,000 BTC over 3.5 hours with a low of $8,900. Now BitMEX have disabled …