Over the last 12-18 months, CleanSpark (CLSK) and IREN (IREN) have grown their Bitcoin mining operations significantly, through use of their at-the-market (ATM) offerings to become two of the highest-performing and most popular companies, amongst the institutional and retail investment communities, using their strategic focus on efficiency, scalability, and sustainable energy use. 

CleanSpark has rapidly expanded its mining capacity, in the last 12 months, currently achieving an energized hash rate of 40.1 EH/s - a 298% increase since January 2024, through a number acquisitions and infrastructure investments while maintaining a strong emphasis on cost-effective, renewable energy sources, reducing operational expenses and increasing profitability. 

IREN has set itself apart with a vertically integrated model, utilizing low-cost, renewable energy from its data centers to enhance efficiency and profitability. In the Bitcoin mining sector, the company has significantly expanded its energized hash rate to 31 EH/s—a 454% increase over the past 12 months. Simultaneously, the company continues to focus on the expansion of its High-Performance Computing (HPC) business, reinforcing its diversified growth strategy.

Both CleanSpark and IREN have benefited from advanced mining technology, operational scale, and disciplined financial management, allowing them to maintain strong hash rates and competitive positioning.  Their focus on sustainability has also made them attractive to investors, mitigating regulatory risks associated with energy-intensive operations. 

In a volatile industry where energy costs and mining difficulty fluctuate, CleanSpark and IREN’s ability to adapt, innovate, and control costs has positioned them as leaders in Bitcoin mining performance.

CleanSpark Reports Strong Fiscal Q1 2025 Results

CleanSpark announced robust financial results for the first quarter of fiscal year 2025, mining 1,945 Bitcoin and reporting a 120% year-over-year revenue increase. The company generated $162.3M in revenue for the quarter ending December 31, 2024, with a net income of $241.7M and basic earnings per share (EPS) of $0.85.

CEO Zach Bradford attributed this growth to continuous improvements in key industry metrics, including operating hashrate, fleet efficiency, and Bitcoin treasury management. CleanSpark exceeded its 2024 guidance, surpassing 40 EH/s per second (EH/s) in January while reducing fleet efficiency to 16.15 J/Th. 

Looking ahead, CleanSpark aims to reach 50 EH/s in the first half of 2025 through expansion projects in Wyoming, Tennessee, and Georgia. CFO Gary Vecchiarelli highlighted the company’s strong financial position, including a $650M convertible bond issuance and a growing Bitcoin treasury, now exceeding 10,500 self-mined Bitcoin.

With a 57% gross margin, $2.8B in total assets, and $1.2B in liquidity, CleanSpark continues to strengthen its balance sheet while capitalizing on its low mining costs. The company remains focused on strategic expansion and capital efficiency, reinforcing its leadership position in the Bitcoin mining industry.

FASB Rules 

In December 2023, the Financial Accounting Standards Board (FASB) introduced ASU 2023-08, requiring Bitcoin and other crypto assets to be measured at fair value each reporting period, replacing the previous cost-less-impairment model. This change now enhances financial transparency and aligns accounting with crypto volatility. It provides investors with a clearer view of a company's digital asset holdings, supporting broader integration into financial reporting.  CleanSpark was effectively able to use this standard to include the unrealised gains on its Bitcoin held in treasury, totalling $260M, without which the company would have effectively reported a net loss.  

IREN Reports Strong Q2 2025 Earnings and Expands AI Data Center Strategy

In the second quarter of fiscal year 2025, IREN nearly doubled its average hashrate, mining 1,347 Bitcoin — a 65% increase on the previous quarter. Cloud services revenue totaled $3M, reflecting a modest quarter-over-quarter decline and falling below the company’s guidance of approximately $8M to $10M per quarter.

In Q2, 2025, total revenues surged 120% quarter-over-quarter to $119.6M, exceeding estimates. Self-mining revenues reached $113.5M, fueled by a 47.5% increase in Bitcoin prices and a 47.6% rise in deployed hash rate to 31 EH/s by December 31. Whilst AI cloud services revenues declined slightly to $2.7M, gross profit jumped to $89.4M, with margins improving to 74.8%, while net electricity costs per Bitcoin decreased significantly to $21,455 per Bitcoin. Adjusted EBITDA rose to $62.6M, marking a 52.4% margin, with net income at $18.9M, equivalent to $0.09 per share.

Operational expenses saw moderate increases, with cash SG&A rising by $4M sequentially, while power costs grew by approximately 25% from Q1, excluding a one-time $7M expense in the previous quarter, for giving early notice to leave an energy hedge position. Notably, power cost growth remained significantly lower than the expansion in hash rate.

Adjusted EBITDA surged to $63M, exceeding the combined total of FY23 and FY24, and reflecting a $60M sequential increase driven by higher Bitcoin production and stronger average Bitcoin prices. This included power costs of $21,455 per coin and cash SG&A of $18,636 per coin, both down sequentially—an impressive efficiency improvement.

IREN also managed to deliver robust Q2, 2025 earnings, reaffirming its mid-year 50 EH/s mining capacity target while adjusting its 2025 year-end outlook to 52 EH/s from the previously forecasted 57 EH/s. This revision follows a strategic decision to allocate 75 MW of capacity at their Childress facility, for a liquid-cooled AI data center, reflecting increasing demand for HPC/AI infrastructure. 

The Management have emphasized its commitment to proving its capabilities in AI and HPC operations, launching the Horizon 1 project, which will support NVIDIA Blackwell GPUs with a 50 MW IT load and rack densities up to 200 kW. The $325M project, expected to be completed by the end of 2025 and could generate over $75M in annual high-margin revenue, positioning IREN as a key player in AI infrastructure.

IREN remains on track to achieve 50 EH/s by mid-year, up from 31 EH/s at the end of January, aided by monthly 50 MW capacity additions at their Childress facility. The company continues to strengthen its low-cost Bitcoin production, enhancing its operational efficiency while leveraging AI opportunities. 

IREN has also announced plans for a large-scale AI data center hub in West Texas. The project includes a new 600 MW site, ‘Sweetwater 2’, which, combined with the 1.4 GW Sweetwater 1 facility, will form a 2 GW data center hub. The company is working on a 600 MW grid interconnection agreement and a direct fiber loop between both sites. If approvals proceed as expected, Sweetwater 1 will be energized by April 2026, while Sweetwater 2 is targeted for energization in 2028. Management believes this development will attract hyperscalers and is actively seeking a single HPC/AI tenant for the facility.

The Cost of Mining a Bitcoin: A Key Metric for Public Bitcoin Miners

For public Bitcoin mining companies, one of the most critical financial metrics is the cost to mine a Bitcoin. Given Bitcoin's extreme price volatility and the substantial energy consumption required for mining, controlling costs is paramount. Many North American miners operate on open market electricity rates, which can also be highly volatile, adding further complexity to cost management.

With energy being the largest operational expense, particularly after the April 2024 halving and subsequent difficulty adjustments, improving fleet efficiency has become more essential than ever. Companies that optimize their mining hardware and energy costs are better positioned to maintain profitability in a competitive and unpredictable market.

Mining Efficiency: IREN vs. CleanSpark

Among publicly traded miners, IREN currently operates the most efficient fleet, achieving 15 J/TH and benefiting from some of the lowest energy costs in the industry. In the last quarter, IREN’s average energy cost per Bitcoin was $21,455, equivalent to $0.03 per kWh, yielding a gross margin of 74.5%.

CleanSpark, the second most efficient operator, reported a fleet efficiency of 16.15 J/TH with an average energy cost of $0.046 per kWh, resulting in a gross margin of 56.7%.

Operating Profit and Cost Per Bitcoin

Beyond energy expenses, total mining costs also include general and administrative (G&A) expenses, payroll, and professional fees. CleanSpark issued a $5.1M dividend for the quarter, representing 2% of net income, and achieved an operating profit of $28,651 per Bitcoin (34.3%). IREN, despite higher G&A costs but lower payroll expenses, reported a stronger operating margin of $44,158 per Bitcoin (52.4%).

Based on these factors, the cost to mine one Bitcoin was:

• CleanSpark: $54,797
• IREN: $40,091

For a more comprehensive understanding of total mining costs, including Depreciation and Amortization, CleanSpark’s total cost per Bitcoin rose to $89,053, while IREN maintained a lower cost of $66,964.

These figures underscore the importance of energy efficiency, cost control, and strategic planning in ensuring profitability in the Bitcoin mining industry. 

Balance Sheet Strength: A Key Indicator for Bitcoin Miners

A strong balance sheet is essential for Bitcoin mining companies to navigate market volatility and sustain operations. Key financial metrics such as the current ratio, net asset value, and debt-to-equity ratio provide valuable insights into a miner's liquidity, financial stability, and leverage.

Current Ratio: Liquidity and Operational Resilience

The current ratio is a critical measure of liquidity, indicating whether a miner has sufficient current assets to cover short-term obligations. Given the capital-intensive nature of mining—requiring significant cash for electricity, hardware, and maintenance—strong liquidity ensures resilience during Bitcoin price fluctuations. A low ratio, on the other hand, may force miners to sell assets at a loss to cover expenses.

CleanSpark maintains a robust treasury of $1.225B, with only $97M in liabilities due over the next 12 months, demonstrating strong liquidity.

IREN, while holding $525M in current assets, has $559M in current liabilities. However, a significant portion of these liabilities relates to convertible notes maturing in 2030, mitigating immediate liquidity concerns. Unlike many peer miners, IREN opts to sell the Bitcoin it produces, frequently, to fund operations rather than holding it as a reserve asset.

Net Asset Value: Equity Strength and Financial Health

The net asset value (NAV) evaluates a company’s financial stability by determining how much of its assets are funded by equity rather than debt. A higher NAV indicates lower reliance on borrowing, reducing financial risk during downturns.

• CleanSpark investors receive $0.71 in assets for every $1.00 invested, reflecting strong equity-backed value.
• IREN investors receive $0.44 per $1.00 invested, suggesting a lower equity position relative to its asset base.

Maintaining a solid net asset ratio is essential for long-term sustainability, particularly in an industry with high operational costs and price volatility.

Debt-to-Equity Ratio: Managing Financial Leverage

The debt-to-equity ratio measures financial leverage and risk exposure. Mining requires significant capital investment, and excessive debt can strain cash flow, particularly during market downturns, as seen in 2022. A lower ratio indicates financial flexibility, allowing companies to endure volatility without liquidity crises.

CleanSpark and IREN both maintain healthy debt-to-equity ratios of 0.32 and 0.30, respectively, suggesting strong financial positioning with manageable debt levels. Their solid balance sheets also provide the capacity to raise additional capital if needed.

Summary

In summary, CleanSpark and IREN have emerged as leaders in the Bitcoin mining industry, demonstrating exceptional growth and performance over the past year. CleanSpark's strategic investments in renewable energy and infrastructure expansion have resulted in a remarkable increase in its hash rate, achieving 40.1 EH/s while maintaining cost efficiency. Meanwhile, IREN's vertically integrated model and focus on low-cost, renewable energy have propelled its hash rate to 31 EH/s, showcasing a commitment to operational excellence. 

Both companies have reported impressive financial results, driven by higher Bitcoin production and improved margins. CleanSpark's robust fiscal performance is complemented by its strong balance sheet, while IREN's expansion into AI and HPC infrastructure positions it for future growth and more predictability when it comes to revenues, margins and net profits. As the Bitcoin mining landscape continues to evolve, CleanSpark and IREN's innovative approaches to sustainability and efficiency solidify their status as top performers, attracting investor interest and setting benchmarks for industry success.

Both CleanSpark and IREN exhibit financial stability, but their approaches to liquidity and capital management differ. CleanSpark holds a substantial Bitcoin Hodl, while IREN frequently sells Bitcoin to fund operations. Their strong balance sheets and conservative leverage ratios position both miners for sustained growth in the ever-evolving Bitcoin mining landscape.