Bitcoin's dominance in corporate treasuries has decreased as companies diversify into altcoins like Ethereum (ETH) and Solana (SOL). In October, over 350 companies globally held Bitcoin, but the pace of buying has slowed. Meanwhile, altcoin treasuries have surged, with firms increasing their exposure to ETH and SOL, and some moving assets on-chain for staking yields. Michael Saylor's firm remains the largest Bitcoin holder with 640,808 BTC, though its market share has dropped to 60% from 75% earlier this year. Metaplanet emerged as the largest Bitcoin buyer in October, adding 5,268 BTC, while Coinbase also increased its holdings. Corporate participation in crypto has more than doubled since January 2025, with 276 companies now holding Bitcoin. Altcoin diversification is evident, with ETH rising to 15% of total corporate crypto holdings from 2.5% in April.