Coinbase Holds About 5% of Bitcoin and Urges Immediate Post-Quantum Fix

Coinbase $COIN, which holds about 5% of all Bitcoin $BTC in existence for clients including banks, asset managers, and hedge funds, published a blog post urging the Bitcoin network to begin preparing immediately for future quantum computing threats. Google researchers project that a cryptographically relevant quantum computer capable of reverse-engineering private keys from public keys and draining wallets could exist by 2029, threatening Bitcoin's current ECDSA and Schnorr digital signature methods. Coinbase recommends flexible transaction formats such as P2MR (BIP-360) and P2TRv2, staged hybrid 1-of-2 transitions, stateless signature options to prevent backup key-reuse flaws, and compatibility with multi-party computation (MPC) systems. The exchange urged developers to separate the contentious debate over long-dormant wallets and lost coins from immediate technical upgrades so governance disputes do not delay broader network protections. "Bitcoin consensus changes, and ecosystem migrations can take years." — Coinbase.