Bitcoin price stayed mostly flat today, hovering around the $86,000 level. At the same time, the rest of the market told a very different story. Most top altcoins dropped between 3% and 10% over the same period, extending a trend that has been building for weeks.
This split is not random. It reflects where capital feels safest right now.
What you'll learn 👉
ETF Flows Are Propping Up Bitcoin
Fresh demand continues to flow into Bitcoin through spot ETFs. U.S. spot Bitcoin ETFs recorded strong net inflows, with Fidelity’s FBTC leading the way after pulling in hundreds of millions of dollars in a single session.
That steady institutional bid helps absorb sell pressure and keeps Bitcoin stable even when broader sentiment turns cautious. Unlike previous cycles, buyers no longer need to touch crypto exchanges directly to gain exposure. ETFs provide deep liquidity, simple access, and a regulated structure that large investors prefer.
Ethereum did not share that support today. Spot ETH ETFs saw net outflows, while smaller inflows into Solana and XRP products were not enough to offset weakness across the altcoin market.
According to SoSoValue, on December 17 (ET), U.S. spot Bitcoin ETFs recorded total net inflows of $457 million. The Fidelity spot Bitcoin ETF FBTC saw the largest single-day net inflow at $391 million. Spot Ethereum ETFs posted total net outflows of $22.43 million, Solana spot… pic.twitter.com/xHFE1UYOHW
— Wu Blockchain (@WuBlockchain) December 18, 2025
Bitcoin Dominance Sends a Clear Signal
Bitcoin dominance jumped to 59.37%, its highest level in nearly a year. That move came as the Altcoin Season Index slid to just 17 out of 100, firmly placing the market back in Bitcoin season.
When dominance rises this fast, it usually means investors are rotating into assets with deeper liquidity and clearer demand. Bitcoin fits that role better than any other crypto right now.
Altcoins, on the other hand, struggle in this environment. They rely more on speculative flows, leverage, and risk appetite. All three are fading.
DeFi Takes the Hardest Hit
The DeFi sector absorbed the worst of the damage. The total DeFi market cap dropped sharply in a single day, wiping out a large chunk of recent gains. Tokens like Chainlink and Hyperliquid underperformed as traders rushed to reduce exposure.
This selling is happening ahead of key macro events, including the upcoming Bank of Japan rate decision. With global liquidity at risk of tightening, traders are cutting positions in areas viewed as higher risk.
Bitcoin benefits from that fear. DeFi does not.
Markets remain sensitive to central bank policy. Any sign of tighter conditions pushes capital toward assets seen as more resilient. Bitcoin now sits in that category due to ETF demand, strong liquidity, and growing institutional ownership.
Altcoins lack those buffers. When stress rises, they fall first.
This does not mean Bitcoin is bullish in the short term. It means it is being sold less aggressively than everything else.
Read also: The Mystery Seller Behind Bitcoin’s Sell Pressure May Finally Be Clear
A Defensive Market, Not a Healthy One
Bitcoin holding steady while altcoins bleed is not a sign of broad strength. It is a defensive posture by investors.
Until liquidity conditions improve and risk appetite returns, this pattern is likely to continue. Bitcoin absorbs flows. Altcoins struggle for attention.
For now, the market is choosing safety over speculation, and Bitcoin remains the closest thing crypto has to a safe harbor.
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