Bitcoin has gained approximately 10.1% in September, putting it on track for its strongest performance in the month since 2012 and challenging a historically weak seasonal pattern. The cryptocurrency rose about 13.8% over the past seven days and 11.6% over the past 30 days, recently moving above $87,000 for the first time since January. The advance was supported by renewed inflows into U.S. spot Bitcoin ETFs and a derivatives short squeeze (rapid buying after bearish bets are unwound), including roughly $999 million of net ETF inflows on Sept. 21. Bitcoin remains roughly flat for 2026 after steep first-half losses and is down about 31% from its $126,080 all-time high recorded last October. The monthly gain has not yet been finalized, with more than a week remaining before the September candle closes.