A day before that split, Hong Kong-based cryptocurrency exchange OKEx forced early settlement of bitcoin cash futures contracts on its platform, which is widely thought to have triggered the sell-off.

Cryptocurrency mining has evolved from a bedroom activity to mass-scale production, undertaken by enterprises that use specialised rigs with application-specific integrated circuits.

These miners typically agree to combine their computing power in so-called mining pools to increase their odds of winning new digital currency. They take into account various factors, including mining difficulty – the total amount of computing power in the network – and costs like electricity and rental fees to decide which coins to mine and where to house their rigs.

The cryptocurrency sell-off has now forced miners to remove at least four models of bitcoin mining machines, including the Antminer S7 and Antminer S9 from Bitmain Technologies as well as Canaan Creative’s AvalonMiner 741, because these have become too expensive to operate under present market conditions, according to estimates by F2Pool on Wednesday.

Beijing-based Bitmain and Canaan, headquartered in the eastern coastal city of Hangzhou, are the world’s two biggest suppliers of cryptocurrency mining rigs. These two companies, along with smaller rival Ebang International, have separately announced plans for an initial public offering in Hong Kong.

Their prospects to float shares in the city now look grim amid the prolonged bear market, which has wiped out more than US$700 billion in the total value of cryptocurrencies since early January. Last week, Canaan let its six-month IPO application lapse.

The latest dive in cryptocurrency prices has started to claim more casualties. Suanlitou, a Hong Kong-based mining platform that allows users to mine bitcoin on a contract basis, said in a statement on Monday that it has suspended all contracts involving Bitmain’s Antminer T9, which was the most in-demand rig in the market. Suanlitou said it was unable to cover management and electricity fees incurred by use of those machines for a 10-day period from November 7.

China is home to some of the world’s biggest cryptocurrency mining facilities, thanks to the country’s cheap coal-fired power in areas like the Xinjiang Uygur and Inner Mongolia autonomous regions. Cryptocurrency miners on the mainland have also taken advantage of the power glut and cheaper rates provided by small hydropower stations, which sparked a government crackdown at the start of this year.

Their struggles, however, represent an opportunity to others. Jack Liao, who runs Shenzhen-based bitcoin mining firm Lightning Asic, said he bought about 50,000 pre-owned bitcoin mining rigs that were put up for sale in the market over the past few days. About 70 per cent of the machines he bought were the Antminer S9 model, which cost him around 500 yuan per unit. A new Antminer S9 goes for up to 3,000 yuan.

Liao said he plans to ship these used rigs to countries with cheaper electricity, such as Russia and Venezuela, so that he can turn a profit selling them there.

He expected the bear market for cryptocurrencies to stretch till next year, with bitcoin prices sinking to as low as US$2,000. “Many people won’t survive,” he said.