Major cryptocurrency exchanges are disclosing how much of their customers’ assets they hold in offline cold storage following last week’s $6.36 billion attack on Binance’s internet-connected hot wallets.

 

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  • Coinbase has disclosed that more than 99% of customer assets are held in cold storage with excess assets continuously transferred offline.

  • Gate has also disclosed that 88.26% of its total assets are held in cold wallets while the remaining 11.74% are maintained in hot wallets. Its newly introduced Proof of Security framework indicates that its cold storage could cover 104.58% of customer assets even if its hot wallets were completely drained.

The figures are undergoing independent third-party review.

 

Other exchanges have also disclosed their storage arrangements.

  • South Korea’s Upbit reported that 99.17% of its assets were held in cold storage as of September 2026 leaving 0.83% in hot wallets.

Its parent company, Dunamu, said the ratio was the highest among the country’s five major cryptocurrency exchanges and exceeded the regulatory minimum of 80%.

Other South Korean exchanges reported lower cold storage ratios:

  • Bithumb: 94.76%

  • Coinone: 85%

  • Digital X (formerly Korbit): 82.79%

  • GOPAX: 80.54%

 

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Meanwhile,

  • OKX’s security disclosure, last updated on September 18, 2026, showed that more than 95% of customer crypto assets were held in cold wallets, with less than 5% in hot wallets.

  • Binance has not disclosed an exact breakdown of its asset storage arrangements. CEO, Richard Teng, has said the vast majority of customer assets are held in cold wallets.

 

The attack, which targeted Binance’s hot-wallet infrastructure, resulted in approximately $6.36 billion in stolen assets, with most of the theft occurring within about 20 minutes, according to blockchain intelligence firm, TRM Labs.

The incident has renewed questions about how exchanges manage the balance between keeping customer assets accessible for withdrawals and protecting reserves against internet-based attacks.

However, cold storage ratios do not provide a complete picture of exchange security. Offline wallets can also be exposed through compromised signing systems, inadequate access controls or employees approving fraudulent transactions.

 

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Hong Kong’s Securities and Futures Commission warned in an August 2025 circular that weaknesses in these systems could compromise both hot- and cold-wallet infrastructure.

The disclosures also require careful comparison as exchanges use different reporting periods and may calculate their cold storage ratios against different asset bases.

 

 

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