Bitcoin Saw Its Best August Since 2017: Can $3.5B In ETF Inflows Help It Beat ‘Red September’?

Bitcoin logged its strongest August in years as ETF demand surged, though analysts warned September could still bring fresh volatility.

• Bitcoin posted its first green in August in five years and its best monthly gain since November 2024.
• Analysts warned September could still bring a seasonal pullback, with some seeing downside toward the $60,000 to $70,000 range.
• Willy Woo estimated that about 5% of the world already owns Bitcoin, slightly above his estimates for gold and the S&P 500.

Bitcoin (BTC) is heading into September with momentum and a seasonal warning sign. The world’s largest cryptocurrency gained roughly 25% in August, its strongest monthly performance since November 2024 and its best August since 2017, as demand for U.S.-listed spot Bitcoin ETFs saw their largest monthly inflows in around 10 months.

This setup has investors debating whether renewed institutional demand and broader adoption can overpower a “Red September” pattern that has historically made the month particularly challenging for BTC.

Bitcoin’s August Rally Was Backed By ETF Demand

Bitcoin ended August in the green for the first time in five years, posting its best month since November 2024 as a late-month rally pushed the cryptocurrency back above $80,000.  

The recovery was accompanied by a strong resurgence in institutional demand. U.S. spot Bitcoin exchange-traded funds saw $3.52 billion in net inflows last month, the best monthly inflow since October 2025, or about 10 months, according to SoSoValue data.

A late-August streak was a major turnaround following earlier outflows, with spot Bitcoin ETFs drawing billions of dollars in a sustained run of positive flows. This makes it the first positive August in five years for Bitcoin, and its strongest monthly ETF inflows in about 10 months could give bulls fresh momentum heading into September, a month that has historically been tougher for the cryptocurrency.  

Can Bitcoin Beat ‘Red September’? 

Historically, Bitcoin has struggled in September, as seasonal risk-off trading and broader market weakness have weighed on the cryptocurrency. Every time July and August ended in green, and September has closed in red—a term often called ‘Red September.' Analyst Benjamin Cowen said, “If August is also green, we might get a seasonal drop in September before a bounce in October.”

Michaël van de Poppe said Bitcoin could still go up around $82,700 and maybe even $90,000. However, he added that a 20 to 40% drop in September or October is still possible. He first thought prices would rise to around $80,000, then drop to around $60,000 to $70,000 in September or October.

Bitcoin’s price was trading at $77,901, up 0.7% in the last 24 hours. On Stocktwits, retail sentiment around the apex cryptocurrency dropped to ‘neutral’ from the ‘bullish’ zone over the past day. Chatter around the token dropped to ‘normal’ from ‘high’ levels.  

Bitcoin’s Adoption To Outpace Gold And S&P 500

As Bitcoin enters September, the asset's adoption story has taken a turn. BTC ownership may already be slightly higher than global ownership of gold and the S&P 500 (SPY), according to on-chain analyst Willy Woo.

Woo said on X that around 5% of the world’s population owns Bitcoin, compared with roughly 4.5% owning gold and 4% owning the S&P 500. “The real question is, where does it top out?” Woo added.

He argued that if Bitcoin ownership remains around 5%, the cryptocurrency would be “no more than a financial asset.” But if adoption eventually reaches a much larger share of the population, Woo believes Bitcoin could take a broader role in the monetary system. Woo suggested a hypothetical 50% adoption level could represent what he described as the “separation of money and state.” 

For updates and corrections, email newsroom[at]stocktwits[dot]com.<