Bitcoin maintained its position near $86,000 on December 18, 2025, despite a sell-off in major altcoins, which saw declines ranging from 3% to 10%. The stability in Bitcoin's price comes as U.S. spot Bitcoin ETFs experienced significant inflows, with Fidelity's FBTC attracting $391 million. In contrast, Ethereum ETFs faced outflows, and overall altcoin flows weakened. Bitcoin's market dominance rose to 59.37%, marking its highest level in nearly a year. Meanwhile, DeFi tokens such as Chainlink and Hyperliquid experienced sharp declines ahead of the Bank of Japan's upcoming rate decision. Market analysts suggest Bitcoin may continue to show strength as investor interest shifts towards the leading cryptocurrency.