Crypto exchanges moved this week to reassure users about how they store assets, disclosing cold storage and hot wallet ratios after an attack on Binance's hot wallet infrastructure last week.
According to TRM Labs, threat actors stole approximately $6.36 billion from Binance's hot wallets, most of it in about 20 minutes. Binance CEO Richard Teng said the "vast majority" of user assets are held in cold wallets, but the company has not provided a precise split.
Gate launches Proof of Security framework
Gate on Thursday launched a "Proof of Security" (PoSEC) framework, reporting that 88.26% of its total assets were in cold storage and 11.74% in hot wallets. The exchange claims its cold storage could cover 104.58% of customer assets even if its hot wallets were completely drained.
"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," Gate said. It noted the data is still undergoing independent review by a third-party audit firm.
Coinbase reports more than 99% in cold storage
In a blog post Wednesday, Coinbase said more than 99% of customer assets are held in offline cold storage and that it continuously rebalances excess assets to cold storage.
"Binance's reported hot wallet incident has understandably left customers asking how Coinbase protects customer assets from something similar happening here," it said.
Upbit cites regulatory minimum
On Tuesday, Upbit, the largest cryptocurrency exchange in South Korea, confirmed it holds 99.17% of its assets in cold wallets, with the remaining 0.83% in hot wallets as of September 2026. The figures are already disclosed to the Financial Supervisory Service.
"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%," a spokesperson for Upbit parent company Dunamu told Cointelegraph, responding to questions about South Korea's call for exchanges to increase cold storage ratios.
"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," the spokesperson added.
Other major South Korean exchanges have reported lower cold-wallet shares. Financial Supervisory Service figures cited in earlier reporting put Bithumb at 94.76%, Coinone at 85%, Digital X, formerly Korbit, at 82.79%, and GOPAX at 80.54% at the end of September.
OKX and comparability caveats
OKX's existing security overview, last updated on Sept. 18, 2026, said it holds more than 95% of client crypto assets in cold wallets and less than 5% in hot wallets.
The reported ratios are not necessarily directly comparable because exchanges use different reporting periods and may calculate cold-storage shares against different asset bases.
Cold storage ratios also offer only part of the picture of an exchange's security. Offline wallets can still be exposed through compromised signing systems, inadequate access controls or employees approving fraudulent transactions.
Hong Kong's Securities and Futures Commission warned in an August 2025 circular that such weaknesses could compromise both hot- and cold-wallet infrastructure.
