Cryptocurrency exchanges moved to reassure users this week by publicly disclosing how they divide assets between cold storage and internet-connected hot wallets, a response to last week’s attack on Binance’s hot wallet infrastructure that resulted in the theft of approximately $6.36 billion.
The disclosures came rapidly. Upbit confirmed its cold storage ratio on Tuesday, Coinbase published a blog post on Wednesday, and Gate launched a “Proof of Security” framework on Thursday. Each exchange emphasized the proportion of customer assets held offline, away from internet access.
Coinbase stated that 99% of customer assets are held in offline cold storage. Gate reported that 88.26% of total assets are in cold storage, with 11.74% in hot wallets, and said this cold storage coverage would cover customer assets 104.58 times over if hot wallets were drained. OKX disclosed that 95% of client crypto assets are in cold wallets and 5% in hot wallets, according to a security overview last updated September 18, 2026.
South Korean exchanges also made disclosures. Upbit held 99.17% of assets in cold wallets as of September 2026, with only 0.83% in hot wallets. A Dunamu spokesperson, Upbit’s parent company, stated: “This represents the highest cold wallet storage ratio among South Korea’s five major KRW-based cryptocurrency exchanges and is substantially above the regulatory minimum of 80%.” The same spokesperson added: “Our aim is to keep our hot wallet holdings at an absolute minimum, with a target of maintaining them below 1% of customer digital assets.”
Other South Korean exchanges reported end-of-September cold storage ratios of 94.76% for Bithumb, 85% for Coinone, 82.79% for Digital X (formerly Korbit), and 80.54% for GOPAX.
Binance CEO Richard Teng said the “vast majority” of user assets are held in cold wallets but did not provide a precise split. The Binance attack occurred over approximately 20 minutes,
Coinbase addressed the incident directly in its disclosure: “Binance’s reported hot wallet incident has understandably left customers asking how Coinbase protects customer assets from something similar happening here.”
Gate’s newly launched PoSEC framework is undergoing independent review by a third-party audit firm. Gate stated: “By publicly disclosing the distribution of assets between platform cold storage and hot wallets, PoSEC provides visibility into asset storage structures and their ability to cover potential losses under extreme scenarios.”
Comparability Challenges
Cold storage ratios are not directly comparable across exchanges because they use different reporting periods and may calculate against different asset bases. South Korea’s Financial Supervisory Service has called for crypto exchanges to increase their cold storage ratios, and the country maintains a regulatory minimum of 80%.
The Hong Kong Securities and Futures Commission warned in August 2025 that cold wallet infrastructure could still be exposed through compromised signing systems, inadequate access controls, or employees approving fraudulent transactions, even when assets are held offline.
