Why September is Historically Weak for Crypto
September has long been a challenging month for cryptocurrencies. Both Bitcoin (BTC) and Ethereum (ETH) have historically underperformed during this time, marked by sharp pullbacks or muted price movements. However, the dynamics in September 2025 have shifted thanks to new all-time highs, ETF flows reshaping liquidity, and potential rate cuts. Could this signal a break from the past, or will the trend of September struggles persist for crypto leaders?
Bitcoin and Ethereum: A Closer Look at 2025
Bitcoin’s exchange reserves have dropped by 18.3% year-over-year, while Ethereum’s reserves saw a more modest decline of 10.3%, indicating strong accumulation trends among long-term holders. Yet, withdrawing addresses present an intriguing divergence: Ethereum addresses surged from 53,333 in 2024 to over 60,000 this year, signifying stronger self-custody practices. On the flip side, Bitcoin’s withdrawing addresses dropped dramatically from 35,347 to just 11,967—a potential indicator of reduced short-term demand but a setup for future growth if key drivers align, such as rate cuts.
The Role of ETF Flows
An essential factor to consider in 2025 is the growing influence of ETFs on market liquidity. Bitcoin ETFs boast a lifetime inflow of $54.5 billion, while their Ethereum counterparts have pulled $13.3 billion since launch. Despite Ethereum’s strong summer with net ETF inflows of $4.08 billion over the last 30 days, September data paints a different picture: Ethereum ETFs face net outflows totaling $135 million, while Bitcoin ETFs have kicked off the month with net inflows of $332 million.
This highlights a critical structural distinction. Bitcoin’s ETFs continue to show resilience, especially in months plagued by market weakness such as September. Ethereum, on the other hand, struggles to maintain momentum, reaffirming Bitcoin’s dominance as the leading crypto asset.
Profit Supply and Market Dominance
Both Bitcoin and Ethereum show significant portions of their supply in profit as of September 2025. Bitcoin holders in profit increased from 76.91% in 2024 to 88.17%, while Ethereum jumped from 73.83% to 92.77%. While this suggests healthy market conditions, it also raises concerns about profit-taking, which could amplify selling pressure in an already historically weak month for crypto.
Ethereum’s dominance has dropped from 15.02% to 13.79%, even as the ETH/BTC ratio has slipped from 0.043 to 0.038. In contrast, Bitcoin’s dominance jumped from 57.46% to 58.82%, signaling enduring confidence in BTC as the benchmark asset during uncertain times.
Short Positions and Liquidation Risks
Another key metric to watch is the imbalance in short positions. Bitcoin currently faces $5.24 billion in shorts compared to $1.83 billion in longs, creating potential conditions for a short squeeze if prices rally. Ethereum shows a more balanced position with $6.55 billion in shorts against $6.10 billion in longs.
This skew underlines Bitcoin’s advantage in September 2025, as its price could trigger rapid liquidation of short positions, driving further gains. For Ethereum, the trajectory remains more tempered due to its balanced derivatives data and a history of underperformance in September.
Expert Forecasts: What’s Next?
Cautious optimism surrounds Bitcoin heading into late September. Analysts predict that maintaining support at $107,557 could pave the way for a breakout above $111,961. For Ethereum, resistance at $4,579 poses an uphill battle, with downside risks if the price dips below $4,156.
Barring surprising upward momentum, Bitcoin appears better positioned to weather the challenges of September. Its historical resilience, stronger ETF flows, and favorable accumulation trends make it the likely leader in the months ahead.
Enhance Your Investment Strategy
For those invested in crypto for the long haul, diversifying your portfolio with high-quality self-custody solutions like the Ledger Nano X (available on Ledger’s official website) offers enhanced security. By reducing reliance on exchange wallets, you can better safeguard your assets.
Conclusion
While September remains a historically weak month for crypto, the market landscape in 2025 introduces significant new variables, including ETF flows and rate cut expectations. Bitcoin emerges as the stronger contender, with structural advantages and historical patterns favoring its stability. However, Ethereum’s potential should not be dismissed entirely, as its growing self-custody trends could signal long-term resilience. As always, perform thorough research and consult with financial advisors before making any investment decisions.
