Historical Data Suggests Ether Could Weaken in September Despite August Rally and ETF Inflows

• Historical pattern: When Ether rose in August (2017, 2020, 2021) it fell the following September.

• New variables: Spot Ether ETFs and corporate crypto treasuries create a different liquidity environment in 2025.

• Market flows: August saw major net inflows into spot Ether ETFs (~$2.79B) while BTC spot ETFs saw outflows (approx. $1.2B).

Meta description: Ether September seasonality: historical September pulls after August gains, now challenged by spot Ether ETFs and treasury demand—read key takeaways and how to prepare.

Since 2016, whenever Ether’s price has gone up in August, it has historically fallen in September, data shows.

Ether’s price has climbed 25% since the beginning of August, but historical data suggests the cryptocurrency could lose steam in September. ETH seasonality has shown repeated August-to-September reversals, though 2025’s ETF inflows and treasury accumulations may change that outcome.

Market participants are watching whether spot Ether ETFs and corporate treasury buys will sustain momentum through September. Crypto trader CryptoGoos noted the question plainly: “ETH seasonality in September during post-halving years is typically negative. Will this time be different?”

Ether is trading at $4,759 at the time of publication, up roughly $952 from its Aug. 1 opening price of $3,807, according to CoinMarketCap. The crypto asset crossed highs above $4,867 following dovish remarks at the Jackson Hole symposium that markets interpreted as easing the path to lower rates.

What does history say about Ether in September?

History shows caution: since 2016, September has delivered an average loss of 6.42% for Ether, based on CoinGlass data. In the three notable years when August was strongly positive (2017, 2020, 2021), each September saw a material pullback.

Since 2016, September has delivered an average loss of 6.42% for Ether. Source: CoinGlass

Examples: 2017 saw a 92.86% August surge followed by a 21.65% September drop. In 2020, Ether gained 25.32% in August and fell 17.08% in September. In 2021, a 35.62% August rise preceded a 12.55% September decline. These outcomes highlight a recurring seasonal vulnerability.

How could 2025 differ from past seasonal patterns?

2025 introduces two major differences: active spot Ether ETFs and sizeable corporate Ether treasuries. Together, these create deeper structural demand that did not exist in earlier cycles. As of Aug. 11, companies with crypto treasuries held more than $13 billion in Ether value, marking a significant on-chain accumulation trend.

Source: Satoshi Stacker

On-chain reporting and blockchain intelligence firms have highlighted large discretionary buys, and market intelligence shows institutional purchases continuing into August. For example, a firm reported that a chairman bought an additional $45 million worth of Ether, bringing a corporate stack to multi-billion levels.

When did spot Ether ETFs and inflows matter most this August?

Spot Ether ETFs attracted roughly $2.79 billion in net inflows during August, while spot Bitcoin ETFs saw approximately $1.2 billion in net outflows, per Farside data. That rotation coincided with a decline in Bitcoin dominance to about 58.19% over 30 days, signaling capital movement into broader crypto assets.

Industry voices noted a “notable shift” in ETF flows toward Ether, underscoring that ETF mechanics can meaningfully influence price discovery and liquidity, especially during seasonally vulnerable months.

Frequently Asked Questions

Will Ether always drop in September after an August gain?

Not always. Historical data shows a tendency, but market structure changes—like spot Ether ETFs and corporate holdings—mean outcomes can differ. Each cycle should be evaluated on current liquidity and flow metrics.

How do spot Ether ETF inflows affect ETH price?

Spot ETF inflows increase institutional demand and can reduce available supply on exchanges, which tends to support price. However, ETF flows are one of multiple factors influencing short-term moves.

Key Takeaways

• Seasonality risk: Historical data points to September weakness after August gains, averaging a -6.42% move.
• Structural change: 2025’s spot Ether ETFs and growing corporate treasuries create a new demand backdrop.
• Actionable step: Monitor ETF flows and large treasury accumulations; consider position management strategies to mitigate seasonal volatility.

Conclusion

Historical patterns show Ether September seasonality has often produced declines following strong August rallies. Yet, the arrival of spot Ether ETFs and significant corporate treasury accumulation in 2025 introduces new demand dynamics that could offset typical seasonality. Stay attentive to ETF inflows and on-chain treasury metrics and adjust risk management accordingly.