Bitcoin tumbled 9 percent in a half-hour on Tuesday, sending prices to the lowest in three months, in a rapid selloff even by the tumultuous standards of the cryptocurrency markets.

As of 21:50, BTC was trading around $8,600, down from a high of $9,812 over the previous 24 hours.

“Even for bitcoin, this is a pretty rare event,” said Qiao Wang, director of product at Messari, a New York-based cryptocurrency-focused data and research firm.

The price started to plunge around 18:30 UTC and stabilized around 19:00.

A trader, who wished to remain anonymous, said the price drop may have been exacerbated by margin calls and contract liquidations on Bitmex, a Seychelles-based exchange that provides customers with 100x leverage, essentially loans to traders that multiply the size of an investment by 100 times.

The margin calls were noted by DataMish, a data platform. We contacted Bitmex for comment but were unable to reach a representative at press time.

BitMex Margin Call Data via DataMish.

The long squeeze

A long squeeze, the opposite to a short squeeze, is a situation in which investors who hold long positions feel the need to sell into a falling market to cut their losses. This pressure to sell usually leads to a further decline in market prices.

Data from Bitfinex also shows long positions falling below -0.005 percent after BTC's rapid price decline forced investors to close out their long positions beginning Midday UTC on Sept. 24 after prices dipped below $9,700.

Bitfinex Funding In Use In Margin Positions Data via DataMish.

While there are some investors who refute data from Bitfinex, due to low numbers and unactionable data, open interest with Bitmex's futures market also took a hit, leading to less than enthusiastic expectations for a quick recovery in BTC's price.

BitMex Total Open Interest and Volumes.

Prices hit $8,627 at time of publishing.

Bear image via Shutterstock