IREN closed its fiscal 2026 books on August 27 with a headline built to sting. The company took a 638.8 million dollar writedown on bitcoin mining rigs it will switch off by the end of December, and its shares fell 6 percent to 38.22 dollars the next day. Most of the coverage stopped at the loss. The full year swung to a 702.6 million dollar net loss, against an 86.9 million dollar profit the year before. That is the version ten other outlets ran.
The writedown the market watched, and the number it skipped
Look one line down the income statement and the picture turns odd. IREN's bitcoin mining revenue for the year climbed 19.3 percent to 578.2 million dollars. Its AI cloud line, the business it is now betting the company on, brought in 128.8 million. Mining still earned more than four times as much.
So the operation IREN is shutting down was not in trouble. It made most of the company's money and grew while doing it. The writedown was a non-cash charge on hardware being retired early, not a mark of machines that stopped working.
What changed was the math on where the next dollar goes. IREN has 4 billion dollars of contracted AI cloud revenue lined up for its 2026 capacity, with roughly 1 billion already running after Microsoft accepted the first Horizon deployment. To feed that, the company raised 6.5 billion dollars of GPU financing in three months. Set a contracted 4 billion dollar run-rate next to a fleet of aging bitcoin mining machines earning 578 million a year, and the machines are the lower-value use of the same power and land. Management said it flatly: mining is decommissioned by the end of December.
Core Scientific and TeraWulf got there first
IREN is not the front-runner here, only the latest to report. Core Scientific booked 136.7 million dollars of colocation revenue in the second quarter against 27.5 million from bitcoin mining, which puts AI and hosting at 83 percent of sales. By any plain reading it is a data-center company that still happens to mine. TeraWulf sits close behind, with high-performance-computing leases at 31.9 million dollars, or 71 percent of revenue.
| Company | Period | AI / HPC revenue | Share of total revenue |
|---|---|---|---|
| Core Scientific | Q2 2026 | 136.7 million dollars | 83 percent |
| TeraWulf | Q2 2026 | 31.9 million dollars | 71 percent |
| IREN | Full year 2026 | 128.8 million dollars | 18 percent |
The contracts behind the shift keep getting larger. Hut 8 has signed AI infrastructure deals worth 26.6 billion dollars. Across the public mining sector, announced AI and HPC commitments now top 70 billion. CoinShares estimates miners could pull about 70 percent of their revenue from AI and HPC work by the end of 2026, up from roughly 30 percent earlier in the cycle. Coinliva flagged the early version of this move, when miners began selling bitcoin and leaning into AI hosting, well before it showed up in the quarterly numbers. None of these firms is bulldozing its plants. They are repointing the land, the power contracts, and the cooling that AI tenants want most toward customers who pay more per megawatt than a block reward does.
What powers down when the rigs go dark
All of this leaves a mark on the network the miners are leaving. Bitcoin's hashrate sat between 850 and 920 exahashes per second in mid-August, roughly 17 percent below the record above 1 zettahash per second it set late in 2025. Difficulty fell as much as 19.9 percent from its own peak in early August, one of the sharper drops of the year.
Hashrate is the rough measure of how much computing power stands behind the chain. When it falls, the theoretical cost of attacking bitcoin falls with it. The long argument over proof of work versus proof of stake has always turned on that hardware sitting behind every block, so a fifth of it stepping away is not a small thing to wave off.
The cause is no mystery. Public miners spent much of the spring underwater, losing something near 19,000 dollars per coin produced in late March, and many chose to sell holdings or repoint machines rather than expand. The bitcoin mining that stays online tends to be the cheapest and most efficient. The marginal rigs are the ones getting written off.
Why the security warning is ahead of the revenue
The tidy conclusion is that miners are abandoning bitcoin and its security is next in line. The revenue map does not back that yet. Earlier in the year, across the ten largest public miners, bitcoin mining still produced about 4.65 billion dollars annually at an 80,000 dollar coin, while confirmed AI revenue ran near 67 million on an annualized basis. The gap was more than 4 billion dollars in mining's favor. Even IREN, the loudest case of the pivot, still earned most of its money from hashing this year.
That gap is what makes the security framing early rather than plain wrong. The risk analysts describe is gradual. Premium sites with cheap, reliable power migrate to AI tenants first, and mining drifts toward lower-quality electricity over time. It is a slow reweighting, not a wall coming down in a quarter. Difficulty adjusts too. When enough machines leave, the reward gets richer for those that stay, which slows the exodus without anyone deciding it should.
The equities are pricing the change faster than the network is feeling it. Some crypto-linked stocks have already been trading below the value of the coins on their books. The date to watch is the end of December, when IREN's rigs go quiet and the company becomes, on its own timeline, an AI landlord that used to mine. If difficulty keeps sliding into the winter, the state of bitcoin mining will be easier to read from the miners who stayed than from the ones cashing out of it.