Bitcoin Mining Pressures Mount as Marathon Signals Possible Reserve Sales

Marathon Digital has formally opened the door to selling its Bitcoin reserves, marking a significant break from the long‑standing pledge to hold its coins indefinitely. The company disclosed the policy change in a 10‑K filing on Monday, telling regulators it may begin selling not only newly mined Bitcoin but also the 53,822 BTC held on its balance sheet. Those reserves were once positioned as untouchable, a core part of the company’s identity and market narrative.

The shift comes as the economics of Bitcoin mining continue to deteriorate. Marathon’s production cost sits at $87,000 per coin while current spot trades near $69,000, leaving every block mined at a loss. Hashprice has fallen to a record low of $35 per petahash, and the company’s own buying activity in 2025 underscores the pressure. Marathon purchased 4,267 BTC on the open market last year at an average price of $111,034, leaving those coins 38% underwater. The company reported a $1.7 billion net loss in Q4 and recorded a $1.5 billion write‑down on its Bitcoin holdings.

A Broad Shift Across the Mining Sector

Marathon is not alone in reassessing its approach. Core Scientific plans to liquidate all 2,537 BTC it holds this quarter, with its CEO describing mining as effectively in runoff. Bitdeer has already reduced its treasury to zero. Riot sold 5,363 BTC across 2025, while Cango moved 4,451 BTC for $305 million. CleanSpark sold 577 BTC in a single month despite producing 7,124 for the year, signaling a treasury that is shrinking rather than expanding.

The common thread is capital rotation. Public Bitcoin miners are increasingly converting Bitcoin into funding for artificial intelligence data center infrastructure, where each megawatt of capacity can generate revenue multiples far higher than mining. One megawatt of mining output earns a mining multiple, while one megawatt of AI cloud capacity can earn three to twenty‑five times that. The spread is wide enough that the decision is no longer philosophical. It is financial.

On the other side of the market, accumulation continues but from a single dominant source. Strategy purchased 3,015 BTC last week at $67,700, bringing its holdings to 720,737 BTC with a cost basis of $54.77 billion, with Saylor's firm currently operating at a loss. It remains the only large‑scale public buyer in a market where nearly every producer is selling. The miners who create new supply no longer want to hold it, while the largest holder has never mined a single satoshi. Production and accumulation have fully separated for the first time in Bitcoin’s sixteen‑year history.

Yet the blockchain presents a more nuanced picture of Marathon’s position. Arkham Intelligence identifies 13,057 BTC in on‑chain wallets linked to the company, far below the 53,822 BTC reported in filings. The remainder sits in custodial or off‑chain arrangements. Since the 10‑K was released, there has been no confirmed on‑chain movement. The filing signals readiness to sell, but the chain shows no activity. That gap is where the real signal may emerge.

If Marathon’s wallets show no material outflows within the next 90 days, the policy shift may amount to optionality rather than intent. If outflows begin while overall crypto market sentiment sits at a Neutral (45), and Bitcoin is already down 22% year‑to‑date, the feedback loop could accelerate and turn miner treasuries into a new source of supply pressure. The 'HODL' era for Bitcoin miners ended when the halving erased margins and AI offered a more profitable path, which just goes to show that miners are in it for the money, not the cause.