The so-called “September effect,” also known in crypto circles as the “September curse,” has historically been a challenging period for cryptocurrencies.
From 2019 to 2022, Bitcoin fell by an average of 8-9% during September. Some years saw larger drops, while others were smaller, but the month consistently shows notable declines.
Currently, the global crypto market capitalisation has fallen below $4 trillion, trading around $3.8 trillion. In September 2025, the market has seen a $162 billion selloff, with the last three to four days experiencing particularly extreme declines.
On some individual days, $1.5 to $1.7 billion in derivatives were wiped out, highlighting the sharp and painful nature of the selloff.
Performance across cryptocurrencies
Bitcoin has been relatively resilient, down by only 1.5% for the month of September. However, altcoins and meme coins have faced deeper cuts. Ethereum is down 12%, Cardano 8.5%, with similar declines in Ripple, Polygon, and meme coins such as Dogecoin and Shiba Inu, where losses range from 4% to 12%.
Several factors have contributed to the drop in crypto prices:
Macro Environment: Weakness across asset classes, slowing US economic growth, and weak jobs data have put pressure on the market. Strength in the US Dollar Index over recent sessions has also added to the decline.
Geopolitical and Policy Concerns: Ongoing geopolitical tensions, a cautious Federal Reserve stance, and crypto encountering resistance after reaching an all-time high in April have weighed on sentiment. Consolidation with lower lows has further contributed to market weakness.
Leveraged Positions and Liquidations: Large liquidations of leveraged long crypto positions, particularly in derivatives, have forced margin calls and subsequent selling, driving prices lower.
Corporate Treasury Actions: Some corporate treasury entities funded Bitcoin and Ethereum purchases with debt. Falling prices have forced these companies to sell assets to repay loans, adding to downward pressure.
ETF Outflows and Regulatory Issues: Net outflows from spot ETFs and stricter regulatory discussions in the US and EU, including AML rules for exchanges, have also impacted the market negatively.
September continues to live up to its reputation in crypto circles, reflecting a combination of historical trends, macroeconomic factors, market mechanics, and regulatory developments.