The bitcoin mining rush is sputtering.
Speculators, known as miners, use powerful computers to solve complex software problems and verify transactions to unlock new bitcoins. They're finding that the enterprise isn't as profitable as it once was.
Drawn by the virtual currency's jump in value last year, digital prospectors have turned the mining industry into an arms race as they buy expensive computing equipment and gobble up electricity. While that worked well as long as bitcoin's value kept rising, smaller players are now being crowded out by bigger competition, high utility bills and declining prices.
"If you mine at the moment, you have to be very lucky to get anything," said Mehmet Vatansever, who bought $16,000 worth of mining computers in February to chase after new bitcoins. "It's a very difficult business."
Mining, a nod to the excavation of minerals and metal ore, is entirely digital and part of bitcoin's design, so that the money self-regulates supply and prevents out-of-control inflation. The mining process gets increasingly complicated as more bitcoins are created, driving demand for computing power.
Bitcoins, which jumped to more than $1,200 last year from $12, fell below $400 apiece last week, according to the CoinDesk Bitcoin Price Index, an average of prices across major global exchanges. China's tighter controls on alternative currencies, the implosion of the Mt.Gox exchange and an Internal Revenue Service ruling that bitcoins should be taxed as a property have all weighed on the virtual currency.
While he has been able to create new bitcoins, Vatansever soon discovered that his equipment was on track to earn less than his monthly utility bill of $480. After selling his computers on EBay in April, Vatansever estimates that he lost a total of about $6,000 on his mining adventure.
In one week earlier this month, miners made $14.9 million in revenue, compared with a weekly average of $25.2 million in December, according to Blockchain.info, an bitcoin-data aggregator. The figures represent the number of bitcoins mined plus transaction fees, multiplied by the dollar-based market price.
EBay now features more than 1,600 listings for mining computers, many of them used.