Coinbase, Gate and Upbit disclose cold storage ratios after Binance hot-wallet attack
In brief
- TRM Labs said attackers took about $6.36 billion from Binance's hot-wallet infrastructure, mostly within 20 minutes.
- Coinbase said more than 99% of customer assets sit in offline cold storage.
- Gate reported 88.26% in cold storage; the figure is still under independent third-party review.
- Upbit reported 99.17% in cold wallets, against South Korea's 80% regulatory minimum.
- Cold storage ratios aren't directly comparable because reporting periods and asset bases differ.
What Binance has (and hasn't) said
Threat actors hit Binance's hot-wallet infrastructure the previous week and took approximately $6.36 billion, according to TRM Labs, with most of it gone in about 20 minutes. Binance CEO Richard Teng said the "vast majority" of user assets are held in cold wallets.
The company hasn't published a precise split.
The numbers, exchange by exchange
In a Wednesday blog post, Coinbase said more than 99% of customer assets are held in offline cold storage, and that it continuously rebalances excess assets to cold storage.
Gate's Proof of Security (PoSEC) framework, launched Thursday, reported 88.26% of total assets in cold storage and 11.74% in hot wallets. Gate claims its cold storage could cover 104.58% of customer assets even if its hot wallets were completely drained. It's worth being clear on status here (Gate says the data is still undergoing independent review by a third-party audit firm, so it isn't an audited figure yet).
"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 in its statement.
In South Korea, Upbit confirmed on Tuesday it held 99.17% of its assets in cold wallets and 0.83% in hot wallets as of September 2026, figures already disclosed to the Financial Supervisory Service. A spokesperson for parent company Dunamu said that's the highest ratio among the country's five major KRW-based exchanges and well above the 80% regulatory minimum. The spokesperson added that Upbit targets keeping hot wallet holdings below 1% of customer digital assets, responding to questions about South Korea's call for exchanges to raise their cold storage ratios. FSS 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's security overview, last updated Sept. 18, 2026, says it holds more than 95% of client crypto assets in cold wallets and less than 5% in hot wallets.
Why a high ratio isn't the whole picture
These ratios aren't necessarily directly comparable. Exchanges use different reporting periods and may calculate cold-storage shares against different asset bases.
Offline doesn't mean untouchable, either. Cold wallets can still be exposed through compromised signing systems, inadequate access controls or employees approving fraudulent transactions, and Hong Kong's Securities and Futures Commission warned in an August 2025 circular that such weaknesses could compromise both hot- and cold-wallet infrastructure.
Frequently asked questions
Why can't exchange cold storage ratios be compared directly?
Exchanges use different reporting periods and may calculate cold-storage shares against different asset bases. Gate reports against total assets, for example, while OKX reports against client crypto assets. That's why the published percentages aren't necessarily directly comparable.
Are assets in cold wallets fully protected from hacks?
No. 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.
What is the minimum cold wallet ratio for exchanges in South Korea?
A spokesperson for Upbit parent Dunamu cited an 80% regulatory minimum. Upbit reported 99.17% in cold wallets as of September 2026. Financial Supervisory Service figures cited in earlier reporting put Bithumb at 94.76%, Coinone at 85%, Digital X at 82.79% and GOPAX at 80.54%.
