ARK Invest, led by Cathie Wood, together with Bitcoin-native financial services firm Unchained, has published a white paper titled "Bitcoin And Quantum Computing". The report states that about 35% of Bitcoin's supply (roughly 6.9 million BTC) carries potential quantum risk, but current quantum computers are still far from capable of breaking Bitcoin's cryptography, dismissing fears of an imminent "Q-Day."
Risk Emerges in Five Phases, Not Overnight
Co-authored by Unchained co-founder Dhruv Bansal, custody research director Tom Honzik, and ARK Invest digital asset associate portfolio manager David Puell, the white paper argues that quantum threat will materialize gradually across five stages. Even if a quantum system reaches the level capable of cracking 256-bit ECC keys, the cost of an attack would be extremely high, and the risk would ramp up progressively.
Address Breakdown: Which BTC Are the Most Vulnerable
The report classifies Bitcoin addresses by quantum vulnerability: about 13 million BTC (65.4% of supply) reside in addresses with high quantum resistance, labeled "non-vulnerable." Around 1.7 million BTC (8.6%) sit in early P2PK addresses (including Satoshi Nakamoto's wallet), and about 5.2 million BTC (26.4%) are in reusable addresses or P2TR addresses, considered high-exposure types. In total, 35% of the supply is potentially exposed to quantum risk.
Internet Will Be Hit First, Giving Bitcoin Time
The white paper provides a key macro perspective: if quantum computing achieves a breakthrough, the first casualty will be the underlying security of the global internet — banking systems, government secrets, and military communications. Such a global crisis would trigger a coordinated response from governments and tech giants, giving Bitcoin ample warning time to upgrade. "The good news is we already know how to defend against quantum attacks," the report says. Bitcoin could undergo a hard fork to introduce quantum-resistant algorithms and require users to move assets to new secure addresses.
Regarding early addresses like Satoshi's wallet, the paper notes that such vulnerable addresses will only face real risk at Phase 3 of the timeline — when a cryptographically relevant quantum computer (CRQC) capable of cracking 256-bit ECC keys emerges. That moment is still far off.