Crypto Exchanges Increase Cold Storage Claims After Binance Attack

The fallout from the Binance hot-wallet attack last week is pushing more exchanges to publicly quantify how much crypto they keep offline. Within days of reports that attackers stole roughly $6.36 billion from Binance’s hot-wallet infrastructure, multiple platforms have published or updated disclosures about their cold-storage shares and how much of customer holdings can be covered under extreme scenarios.

The releases matter because they shift the discussion from general assurances to specific asset-allocation numbers—although those figures can still be hard to compare across companies due to differing calculation methods, reporting dates, and security architectures beyond storage alone.

Key takeaways

• Gate launched a “Proof of Security” (PoSEC) framework, reporting 88.26% of assets in cold storage and 11.74% in hot wallets, with cold storage capable of covering 104.58% of customer assets in a worst-case hot-wallet drain.
• Coinbase says more than 99% of customer assets are stored in offline cold storage and that excess assets are continuously rebalanced back to cold storage.
• Upbit (Dunamu) reported 99.17% of assets in cold wallets and 0.83% in hot wallets as of September 2026, framing it as above South Korea’s 80% regulatory minimum.
• Reported cold-storage ratios may not be directly comparable because exchanges may use different asset bases and reporting periods.
• Cold storage is only one part of custody security; regulators have previously warned that signing systems, access controls, or internal processes can still create vulnerabilities across both hot and cold setups.

More exchanges publish cold-vs-hot ratios after Binance incident

After threat actors targeted Binance’s hot-wallet infrastructure, stealing approximately $6.36 billion in what TRM Labs characterized as the largest hack in history, other exchanges moved to address customer concerns by sharing storage distribution details. Binance CEO Richard Teng said the “vast majority” of user assets are held in cold wallets, but the company has not published a precise split between cold and hot holdings.

That gap is exactly what many traders and depositors appear to be asking for: concrete numbers that indicate how much of customer crypto is exposed to internet-connected systems. This week’s disclosures show a clear trend toward higher transparency around internal custody practices.

Gate introduces PoSEC disclosure and coverage claim

Gate, a crypto exchange, said on Thursday that it launched a “Proof of Security” (PoSEC) framework designed to make the exchange’s asset storage structure more visible. According to Gate’s disclosure, 88.26% of its total assets are held in cold storage while 11.74% are kept in hot wallets.

Gate also claimed its cold storage can cover 104.58% of customer assets even if its hot wallets were “completely drained.” The exchange said the data is still undergoing independent review by a third-party audit firm.

From an investor perspective, that “coverage” framing is a notable shift. Rather than only stating a cold-wallet percentage, Gate ties the number to an explicit stress scenario, which may help customers interpret what a hot-wallet compromise could realistically affect.

Coinbase: over 99% offline and continuous rebalancing

Coinbase entered the discussion in a blog post published Wednesday, stating that more than 99% of customer assets are held in offline cold storage. The exchange added that it continuously rebalances excess assets back to cold storage.

Coinbase’s message directly referenced the market reaction to Binance, noting that customers are understandably asking how it protects assets from similar incidents. While Coinbase did not provide a precise hot-wallet percentage in the excerpted material, its emphasis on maintaining an overwhelming majority offline aligns with broader industry expectations in the wake of the Binance attack.

Upbit reports near-total cold storage as South Korea tightens focus

Upbit, described as South Korea’s largest cryptocurrency exchange, 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 were said to be already disclosed to the Financial Supervisory Service.

In comments provided to Cointelegraph, a spokesperson for Upbit parent company Dunamu said the 99.17% share represents the highest cold-wallet storage ratio among South Korea’s five major KRW-based exchanges and is substantially above the regulatory minimum of 80%. Dunamu also said its goal is to keep hot-wallet holdings at an absolute minimum, with a target of maintaining them below 1% of customer digital assets.

The contrast is sharpened by earlier disclosures cited in reporting: Bithumb at 94.76%, Coinone at 85%, Digital X (formerly Korbit) at 82.79%, and GOPAX at 80.54% at the end of September. While those numbers suggest many exchanges are meeting minimum requirements, they also show that “above the minimum” can still involve materially different levels of exposure depending on each operator’s policies and implementation choices.

Ratios aren’t everything: regulators warn about deeper custody risks

Even with more published cold-storage ratios, the industry is still grappling with an important limitation: these percentages do not fully capture security. Cold wallets can remain at risk if the systems that authorize transactions are compromised—for example, through weak signing controls, insufficient access management, or employees approving fraudulent transfers.

The article notes that Hong Kong’s Securities and Futures Commission warned in an August 2025 circular that weaknesses in processes and controls could compromise both hot- and cold-wallet infrastructure. That kind of regulatory framing highlights why storage distribution alone should not be treated as a complete safety metric.

There’s also an additional analytical challenge. Exchanges may calculate cold-storage shares using different asset bases and reporting timelines. As a result, even when published numbers appear similar, readers should avoid assuming they are directly comparable.

OKX, for instance, previously stated in an existing security overview updated on Sept. 18, 2026, that it holds more than 95% of client crypto assets in cold wallets and less than 5% in hot wallets. But differences in methodology can still make cross-exchange comparisons imperfect.

What to watch next

As more exchanges publish storage distributions in response to the Binance incident, the key question will be whether the industry moves beyond percentages toward more comprehensive disclosures about custody controls—especially the operational safeguards that protect transaction signing and approvals when both hot and cold systems are involved.