Altcoin perpetual futures open interest surpassed Bitcoin's on September 6, marking the first such crossover since December 2024, with altcoin open interest reaching roughly $40 billion versus Bitcoin's $23.9 billion. Zcash led the surge, with its open interest hitting a record $2.4 billion as the token's price jumped 134% in 30 days, briefly touching $1,023 on September 4. Solana, XRP, and Ethereum also contributed, each outperforming Bitcoin's 24% monthly gain, though they remain more than 40% below year-ago levels. Spot demand appears to be supporting the move, as altcoin market capitalization outside the top 10 has climbed above $200 billion, up over 10% since September. However, the last time this crossover occurred in December 2024, several mid-cap altcoins corrected sharply within weeks, and heavy leverage in Zcash poses a risk of forced liquidations if prices reverse.