Bitcoin Mining Centralization Reaches Decade High as Two Pools Control 51% of Hashrate

Bitcoin, long considered the gold standard of decentralized finance, is facing growing concerns about the concentration of its mining power. Recent data reveals that just two mining pools—Foundry USA and AntPool—now control over 51% of Bitcoin’s total hashrate, raising fears about network security and the potential for a theoretical 51% attack.

According to analyst Jacob King, Foundry currently holds a 33.63% market share of Bitcoin’s mining hashrate, while AntPool accounts for 17.94%. This combined control of more than half the network’s processing power has alarmed many within the cryptocurrency community.

Two Bitcoin mining pools now control over 51% of the network. The door is wide open for a 51% attack, which could completely destroy BTC.

For context, the last and only time this happened was 11 years ago, in 2014, with GHash,io. They had to voluntarily reduce their hashrate to… pic.twitter.com/SMLpVrGGdG

— Jacob King (@JacobKinge) August 19, 2025

The concentration of mining power has reached levels not seen in more than a decade. Some community members have openly acknowledged that Bitcoin mining has become “extremely centralized,” with statistics from Evan Van Ness showing that three mining pools frequently hold over 80% of the global hashrate.

This centralization directly challenges one of Bitcoin’s core principles: its decentralized nature. The cryptocurrency was designed to operate without central control, but the current mining landscape paints a different picture.

The 51% Attack Risk

A 51% attack occurs when a single entity or coordinated group controls more than half of a network’s mining power. While executing such an attack would be extremely costly—estimated at around $1.1 trillion—the theoretical possibility exists.

If such an attack were to occur, the controlling mining pools could potentially manipulate transaction validation, block or reverse confirmed transactions, and even enable double-spending. These actions would compromise the Bitcoin network’s integrity and could cause financial losses.

Foundry USA recently demonstrated its outsized influence by mining eight consecutive blocks, an occurrence described as highly unusual. This streak highlights the growing imbalance in mining distribution and raises questions about the health of the network.

The rise in empty blocks—those containing no transactions—adds another layer of concern. These blocks generate minimal fees and suggest that miners are prioritizing speed over profitability, potentially reducing transaction efficiency and network revenue.

Market Impact and Price Pressure

Bitcoin’s price has been sliding toward a critical support level near $110,530, a threshold that traders are watching closely. Technical indicators, including the relative strength index and 20-day moving average, currently show bearish momentum.

If the price holds above this support level, some analysts believe a rebound toward $120,000 is possible. However, a breakdown below $110,530 could signal further declines toward $107,000 or even $100,000.

The centralization concerns come at a challenging time for Bitcoin and the broader cryptocurrency market. Macroeconomic factors, including a shift in Federal Reserve policy and the newly passed Genius Act stablecoin bill, have added pressure to crypto markets.

Fears of a potential $6.6 trillion withdrawal from the stablecoin sector have raised systemic risks, creating a difficult environment for Bitcoin and other cryptocurrencies.

While proponents argue that no rational actor would spend billions to destroy the network that sustains their investment, the perception of vulnerability is already affecting market confidence.

The hashrate and difficulty of Bitcoin mining are currently at record highs, but concerns over a potential 51% attack have added psychological pressure to the market.

Critics warn that this situation could transform Bitcoin from a decentralized asset into a perceived “risk and burden” for institutional investors. This shift could also impact the broader financial system.

Many experts are questioning whether the Proof-of-Work (PoW) mechanism remains suitable to serve as the backbone of a global financial system. Its vulnerabilities, such as the risk of a 51% attack, raise concerns about its long-term viability.

The current mining concentration is forcing the Bitcoin community to reconsider fundamental aspects of network governance and security. As hashpower continues to concentrate among a few dominant players, close monitoring of network dynamics will be essential.

Bitcoin’s price currently hovers near $110,530, with traders watching for signs of either recovery or further decline amid these centralization concerns.