The price of the digital currency bitcoin hit a two-year high, trading above $700 on Monday morning after it spiked 21% over the weekend as traders raced in front of an unusual event called the “halving,” an adjustment to bitcoin’s protocol designed to control the creation of new coins.
Most recently, it was trading at $703. The last time the currency was this high was February 2014, when it was coming down from its December 2013 all-time high of $1,147.
The weekend surge is on top of a first spike in May that took the price from under $450 – where it sat for most of 2016 – to over $550.
Any time you’re talking about bitcoin prices and the reasons for any move, it’s best to keep in mind that this is still a relatively thin market. The volume of bitcoin traded over the past 24 hours was about 40,000, worth about $277 million, according to coincap. That’s large by cryptocurrency standards, but small by capital market standards; this is still a market that can be pushed by a small amount of trading. Don’t forget China, either. A lot of trading comes from China, where bitcoin is an enthusiastically speculative market. Lastly, the risk-off selling in the wider capital market sometimes triggers bitcoin’s gold-like qualities, driving a small store-of-value crowd into the currency.
The more important factor, though, is almost surely a rare event in the bitcoin world that is coming within a month: the “halving.”
A quick explanation: Bitcoin is designed to be run by a network of computers that independently confirm transactions on the network. To ensure that individuals are willing to contribute their computing power, a reward is included for every block of transactions confirmed: a batch of newly created bitcoins. Because this process somewhat resembles physical mining, the contributors are dubbed the miners.
When bitcoin was released, it had a “cap” programmed into it: no more than 21 million bitcoins would ever be produced (about 15.7 million have been mined so far). To ensure that those bitcoins would be mined over a long time (well into the next century), certain speed bumps were programmed in. One was a roughly ten minute lag between confirmed blocks. The other was a quadrennial reset of the mining reward, an event called the “halving.” Every four years, the mining reward is cut in half. When bitcoin launched, the reward was 50 bitcoins. In 2012, it was cut to 25. In less than 30 days, it will be cut again, to 12.5 bitcoins.
This second “halving” is currently slated to occur in about 26 days.
It isn’t exactly clear what will happen during this halving. On the one hand, it should have a pretty predictable supply-and-demand effect: with the supply getting cut, demand should push prices higher. That is what seems to be happening now, as traders are essentially “front running” the halving.
On the other hand, the bitcoin network has changed dramatically in four years. At the last halving, on Nov. 28, 2012, bitcoin was still a tiny, mostly hobbyist network, with miners still using desktop computers and graphics cards. Now miners are multi-million, enterprise-level operations. Cutting the reward in half could wreak havoc with their business models. Already, one miner, Sweden-based KnCMiner, has filed for bankruptcy protection. If the price rises enough to offset the lowered reward, then the other miners will chug happily along.
If miners were profitable at $450, they should still be profitable at $900, and they’ve got 26 days to get bitcoin’s price there. If the price doesn’t hew to the laws of supply and demand – and this is still an unusual experiment in currency creation, remember – then the miners could be in for a rough storm.
UPDATE: an earlier version of this post included a different number for the 24-hour trading volume.