Binance holds 85% of its Bitcoin (CRYPTO: BTC) in quantum-exposed outputs, while Coinbase Global Inc. (NASDAQ:COIN) sits at 5%, according to Glassnode data analyzing which coins are vulnerable to future quantum computer attacks.



<h3>6.04M BTC Currently Quantum Exposed At Rest</h3>



Glassnode identified 6.04 million BTC, or 30.2% of issued supply, as quantum exposed. These coins are vulnerable because their public keys are already visible on the blockchain.



The threat: future quantum computers could potentially crack the private key from a known public key and steal the coins without waiting for the owner to move them.



Exposure comes from two sources. Structural exposure (1.92 million BTC, 9.6%) affects coins using older Bitcoin address types and newer Taproot addresses. 



Operational exposure (4.12 million BTC, 20.6%) affects coins where owners reused addresses—once you spend from an address, the public key becomes visible, exposing any remaining balance.



<h3>Address Reuse Creates Operational Exposure</h3>



Operational exposure represents the larger bucket—coins that become exposed because the public key was already revealed while BTC remains associated with the same address.



This address-reuse problem affects outputs like P2PKH, P2SH, P2WPKH, and P2WSH.



Exchanges account for 1.66 million BTC, or 8.3% of total supply, within the operationally unsafe bucket. 



This represents 40% of all operationally unsafe Bitcoin and roughly half of labeled exchange-held BTC.



Entity-level data shows massive variance. Coinbase labeled balances sit at only 5% exposed. Meanwhile, Binance and Bitfinex show 85% and 100% exposure respectively.



<h3>Fidelity At 2%, Robinhood At 100%</h3>



Fidelity and CashApp sit near 2% quantum exposure. Grayscale holds roughly 50% exposed, while Robinhood Markets Inc. (NASDAQ:HOOD) and WisdomTree are 100% exposed.



Sovereign treasuries show zero public-key exposure. 



The U.S., U.K., and El Salvador maintain 0% quantum exposure through proper address management.



Governments have held above 99% operationally safe for years. Meanwhile, exchanges have drifted downward from roughly 55% in 2018 to 45% today—a trend easily reversible through standard address-management practices like avoiding reuse and rotating change outputs.



<h3>Not An Immediate Risk Signal</h3>



Glassnode stressed this is not an immediate risk ranking or solvency signal for any exchange. The data simply shows custody design leaves an observable on-chain footprint.



Quantum readiness extends beyond protocol-level questions. A meaningful share of measurable exposure sits with active entities that can reduce it through operational choices.



Address hygiene, reserve management, reduced key reuse, and migration planning are practical levers available today.



Image: Shutterstock

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Binance holds 85% of its Bitcoin in quantum-exposed outputs, while Coinbase has only 5%, according to Glassnode data. A total of 6.04 million BTC, or 30.2% of the supply, is vulnerable to future quantum computer attacks. Operational exposure, primarily due to address reuse, affects 4.12 million BTC. Despite the risks, Glassnode indicates this is not an immediate threat to exchanges, as proper address management can mitigate exposure.

- According to Glassnode, Binance holds 85% of its Bitcoin in quantum-exposed outputs, while Coinbase has only 5%.  
- The study found that 6.04 million BTC, or 30.2% of the issued supply, is vulnerable to future quantum computer attacks, primarily due to public key visibility on the blockchain.  
- While this exposure is significant, Glassnode notes it is not an immediate risk and highlights the potential for exchanges and entities to improve their quantum readiness through better address management practices.

Coinbase's Bitcoin Is (Mostly) Quantum-Proof—But Binance's Is Not