In the last ten days, three public Bitcoin mining companies announced they had reached 50 exahashes per second (EH/s) of processing power contributed to the network. These companies are IREN Limited (IREN), Cango (CANG), and CleanSpark (CLSK). 

Cango achieved these hashrate levels on July 1, IREN announced it on June 30, and CleanSpark did the same on June 24. Thus, together with MARA (MARA), the largest miner by market capitalization in the world, these companies account for over 200 EH/s, representing approximately 20% of the global hashrate of 874 EH/s, according to data from mempool.space (MARA operates another 50 EH/s).

As competition for hashrate intensifies, the Bitcoin protocol benefits from increased security, but miners face the challenge of balancing energy costs, operational efficiency, and financial strategies. However, the fact that four miners control a fifth of the global hashrate raises questions about the concentration of power in mining. 

Criticism of IREN for its BTC sales strategy 

Unlike competitors like MARA, which has nearly 50,000 bitcoins on its balance sheet, IREN, one of the newcomers to the 50 EH/s milestone, adopts a strategy of selling mined bitcoins daily to minimize financial risks and link its performance directly to operations. This practice has drawn criticism.

IREN data center located in Mackenzie, Canada. Source: IREN.

For example, one user on X pointed out that IREN's market cap of $1.8 billion, according to Hashrate Index, is not backed by bitcoin holdings, unlike MARA ($5.5 billion), whose value reflects its reserves.  

Additionally, IREN is diversifying into artificial intelligence and high-performance computing, following a trend among miners looking to leverage their energy infrastructure for sectors other than mining.