Three of the world's largest bitcoin mining equipment makers plan to raise billions of dollars with initial public offerings in Hong Kong, even as other companies report plunging demand for the chips needed to make bitcoin and a halving in the price of the crypto currency.
           
Soaring cryptocurrency prices last year triggered a boom in demand for specialist mining chips and in developing "mines" - facilities with thousands of machines that create the coins by solving complex mathematical puzzles.
           
Yet the US chipmaker Nvidia Corp said this month that second-quarter sales to crypto miners totalled just $18 million, compared with $100 million expected by analysts.
           
Nvidia's chief financial officer, Colette Kress, said she anticipated "no contribution" to revenues from cryptocurrency incoming months.
           
That has raised concerns about the upcoming Hong Kong listings by three Chinese manufacturers of bitcoin mining equipment, Bitmain, Canaan Inc and Ebang International Holdings.
           
The companies all design high-end computer chips intended for mining cryptocurrencies, particularly bitcoin, and sell mining equipment containing the chips. In addition, Bitmain mines cryptocurrencies on its own account. Companies like Nvidia also sell specialty chips used for mining.
           
"The marked decline in the price of bitcoin since the start of the year is likely to weigh on investors' interest in these companies," said Benjamin Quinlan, chief executive of financial services consultancy Quinlan & Associates.
           
But, he added, "the fall in the price of bitcoin from its peaks has not been matched by an equivalent fall in the numbers of people mining it."
           
Bitcoin is currently trading at $6,699, down 64% from its December 2017 peak of $18,690. Daily mining revenue was 77% lower than in December, according to Blockchain.info, a data analytics and wallet provider.    

"As the bitcoin price decreases, so does the profitability of mining itself, which decreases demand for mining chips and miners," said Wang Leilei, a consultant at financial services consultancy Kapronssia.
           
It is not just the price of bitcoin that is causing worries. People close to the IPOs said regulatory scrutiny and a patchy performance by Hong Kong offerings this year were additional concerns.
           
Julian Hosp, president of TenX, a Singapore-based blockchain firm, has also warned that if coins switch mining algorithms, then the machines designed to mine them would become useless.
           
"I would be quite wary of investing in these miners," Hosp said, referring to the equipment makers. "They are not long-term businesses and I think they've had their uptrend for now."