On paper, the four companies are in the same league. All reported 50 EH/s or more in deployed hashrate last month, with MARA topping the group at 58.9 EH/s, followed by CleanSpark, Cango and IREN each at 50 EH/s. In practice, however, the amount of that capacity actually producing bitcoin — known as realized hashrate — varied.

IREN came out on top, converting its 50 EH/s deployment into an implied realized hashrate of 45.5 EH/s. That was enough to produce more bitcoins in July than MARA, despite MARA’s substantially larger deployed fleet. MARA’s realized capacity came in at 43.9 EH/s, CleanSpark’s at 41.9 EH/s, and Cango’s at 40.7 EH/s.

Despite three of the four realizing less than 90% of their fleets in July, their combined production accounted for 19.07% of all bitcoin block rewards that month — the highest monthly share they’ve ever achieved. With seasonal power curtailments likely to ease after the summer, their combined share could easily break the 20% mark in the coming months. That would mean one in every five bitcoin mined globally comes from just four public companies.