Bitcoin Security Stress-Tested: Foundry Hashrate Plunges 60% as Winter Storm ‘Fern’ Freezes US Miners
Foundry USA lost 200 EH/s in 48 hours as miners shut down for Winter Storm Fern, exposing the fragility of Bitcoin’s US-centric security model.
The physical centralization of Bitcoin’s hash power just faced a reality check. As Winter Storm Fern battered the United States this weekend, Foundry USA, the network’s largest mining pool, saw its hashrate collapse by approximately 60%, stripping nearly 200 exahashes per second (EH/s) from the blockchain. The drop briefly pushed global block production times to 12 minutes, slowing transaction processing as the network struggled to adjust.
The Curtailment Cascade
This wasn’t a hardware failure; it was economic logic in action. As temperatures plunged across the US Southeast and Midwest, demand for heating spiked the electrical grid. In response, industrial-scale miners executed voluntary curtailment strategies, powering down rigs to resell electricity at premium crisis rates or to comply with demand-response contracts.
Foundry USA’s pool hashrate fell from nearly 340 EH/s to roughly 140 EH/s, signaling that U.S. infrastructure now represents a single point of failure for over a quarter of the network’s security budget.
Data from Hashrate Index confirms the steep decline began late Friday, mirroring the storm’s trajectory. While the Bitcoin price held steady near $87,500, the event validates long-standing fears: the geographic migration from China to the US has simply swapped one jurisdiction of concentration for another.
Institutional Implications
For institutional allocators, this is a live-fire stress test. The network lost roughly 10-30% of its total global security variance in 48 hours. While the difficulty adjustment algorithm will eventually normalize block times, the immediate lag exposes the latency risks inherent in regionally concentrated mining. Similar to the 2021 regional outages in China, this incident degrades short-term market quality by increasing fee volatility and confirmation delays.
Miners like Riot and Marathon (often constituents of Foundry’s pool) are effectively operating as grid batteries first, and transaction processors second. As US weather patterns become more volatile, the “reliability” of North American hashrate is no longer a given.
