Bitcoin’s (BTC) slide into September comes with an uncomfortable reminder for traders that history is not on their side.

The largest token by market capitalization has declined in nine of the last 14 September months, with an average monthly loss of around 12%.

This seasonality looms large again in 2025. Bitcoin opened the week near $110,000, its weakest level in nearly two months, and total crypto market capitalization has slipped to $3.74 trillion, reaching a three-week low.

BTC prices have been flat over the past 24 hours, with Solana’s SOL (SOL) leading gains at 4%, XRP (XRP) posting 1% and Cardano’s ADA (ADA) rising 1.5%.

Traders say the combination of macro uncertainty, fragile sentiment, and thinning volumes leaves little room for error heading into what has historically been the toughest month on the calendar.

The technicals don’t inspire much confidence either. Alex Kuptsikevich, chief market analyst at FxPro, noted that the broader capitalization chart “continues to record a series of lower lows, signaling a downward trend.”

He pointed to Bitcoin’s failure to hold $112,000 and warned of “further decline toward the $105,000 area,” a level that has long acted as support before the psychological $100,000 barrier.

The crypto fear index has slipped back toward 40, its lowest since April, suggesting nerves are rising before they’ve fully broken.

In 2017, bitcoin dropped nearly 8% in September despite the euphoric rally that carried it to $20,000 later that year. In 2019, the token lost almost 14% in September, foreshadowing months of sideways action.

Even in the latest cycle, September 2021 and 2022 both saw steep drawdowns, reminding traders that liquidity drains and macro jitters often coincide with the end of summer.

This year, those headwinds are visible in ETF flows. After steady accumulation through much of August, spot bitcoin ETFs in the U.S. recorded net outflows of $440 million last week.

Ether ETFs, which launched just last year, posted more than $1 billion in inflows, marking a rare bright spot but also a sign that capital may be rotating rather than growing overall.

Meanwhile, CryptoQuant data shows spot ETFs have now absorbed more than 1.3 million BTC, nearly 6% of total supply, putting them on par with the largest exchanges for market share.

The risk is that support levels break before macro relief arrives. Non-farm payrolls due Friday are expected to show just 45,000 new jobs, confirming a slowing U.S. labor market.

A soft print would strengthen the case for a September rate cut from the Fed, a catalyst that could flip sentiment back to risk-on. Until then, traders are paying up for downside hedges.

Options data shows the strongest demand for puts in weeks, with skew leaning firmly bearish, FxPro’s Kuptsikevich noted, calling for caution among intra-day traders.