CoinShares says the quantum threat to Bitcoin is smaller than many investors fear
CoinShares argues that quantum computing is a real long-term engineering risk for Bitcoin, but far from an imminent market shock. The firm says the coins that could cause meaningful disruption are concentrated in a relatively small set of legacy outputs, while a protocol upgrade and user migration would have years to play out.
Quantum computing keeps resurfacing as a Bitcoin doomsday scenario. The worry is familiar: a future machine runs Shor’s algorithm, derives private keys from exposed public keys, and drains old wallets before the network can react.
A new research note from CoinShares takes the temperature down. The firm says the risk is worth planning for, yet the “everyone is vulnerable” narrative skips over how Bitcoin addresses actually work and how slow the leap to cryptographically relevant quantum hardware is likely to be.
CoinShares breaks the exposure into two buckets. The most sensitive coins sit in legacy Pay-to-Public-Key (P2PK) outputs, where the public key is already visible on-chain. CoinShares puts that pool at roughly 1.6 million BTC, about 8% of supply. Even there, it argues the market impact is constrained because most of the balance is fragmented across tens of thousands of small UTXOs.
The number CoinShares thinks could matter in a “sudden” scenario is far smaller: about 10,200 BTC. Those coins are concentrated in a limited set of larger legacy outputs that, if compromised quickly, could create noticeable supply pressure. Everything else in the vulnerable bucket is spread across roughly 32,000 UTXOs of about 50 BTC each, which CoinShares says would take an implausibly long time to drain even under optimistic assumptions about quantum progress.
On timelines, the note leans on hardware reality. CoinShares cites academic work suggesting that reversing a Bitcoin public key within a day would require around 13 million physical qubits with strong error correction, roughly 100,000 times larger than today’s biggest machines. Pushing that window down to an hour would require performance millions of times beyond current systems.
CoinShares also stresses what quantum computers do not change: they cannot lift the 21 million cap or bypass proof-of-work. For mitigation, the firm points to the path Bitcoin has used before: gradual upgrades. Modern address formats keep public keys hidden until coins are spent, and a future soft fork could add post-quantum signatures while giving users time to move funds.
For investors, the practical takeaway is that quantum risk is a horizon issue with warning signs. The urgent variable, CoinShares suggests, is preparation and upgrade coordination, not a near-term cliff that forces panic selling.
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