Investment bank Jefferies reported that Bitcoin mining profitability declined over 7% in September 2025, driven by weaker Bitcoin prices and a sharp rise in network hash rate.During the month, Bitcoin fell 2%, while network difficulty increased as the hash rate jumped approximately 9%, placing further strain on miner margins heading into Q4 2025.Data showed that North American listed mining companies produced 3,401 BTC, down from 3,576 BTC in August. Their share of the global network also slipped from 26% to 25%.Among public miners, MARA Holdings produced 736 BTC, up from 705 BTC in August, while CleanSpark followed with 629 BTC, down from 657 BTC.According to Jefferies, a mining cluster with 1 EH/s hash rate earned roughly $52,000 per day in September, compared with $56,000 in August and about $43,000 a year earlier.The report concluded that the price weakness and rising network difficulty continue to squeeze margins in the Bitcoin mining sector, with profitability risks likely to persist into the fourth quarter.