Ark Invest: Quantum computing a gradual structural risk to Bitcoin; ~1/3 in older or reused addresses at risk

Ark Invest says current quantum computers are far from breaking Bitcoin's cryptography and that any real threat would likely emerge gradually, giving the network time to adapt ^[1].

Ark and custody partner Unchained estimate roughly one‑third of Bitcoin (about 34.6%) — mainly coins in early, reused and Taproot addresses — could be vulnerable if future quantum computers can break today’s cryptography ^{[2] [3]}.

Ark framed the quantum issue as a structural tail risk concentrated in legacy address types, stressing mitigation and transition planning rather than signaling an imminent compromise of the Bitcoin network ^{[1] [2]}.

Bottom line: Ark positions quantum computing as a long‑term, manageable risk — not an immediate threat — while warning that roughly one‑third of BTC remains structurally exposed to a future breakthrough, highlighting the need for coordinated mitigation over time ^{[1] [2] [3]}.