Top 5 Altcoins to Buy in September 2026: The Coins Bitcoin Left Behind

Bitcoin has just closed out its strongest stretch of 2026. The price climbed from roughly $62,800 in early August to above $80,000 on 25 August, a gain of about 22% in a single week and close to 28% across the month. It was Bitcoin's best weekly performance since 2023.Momentum came from several directions at once. The US Treasury doubled the size of its bond buyback operations, renewed movement behind the Clarity Act lifted risk appetite, and roughly $2.7 billion in short positions were force-closed on the way up. Spot Bitcoin ETF inflows, negative for the year at one point in 2026, turned positive again through July and August.One thing worth keeping in perspective before anyone calls this a new bull market: Bitcoin peaked at $126,198 in October 2025 and fell to a 21-month low near $59,300 in June 2026. At $80,000 the asset is still roughly 37% below its record. This is a recovery, not a breakout to new highs.AdvertisementIs the entire crypto market up, or just Bitcoin?The whole market is up, but $Bitcoin is still taking the larger share, and that gap is where the opportunity sits.The total crypto market capitalisation now sits near $2.75 trillion. The altcoin market excluding Bit...