Bitcoin and ether fell sharply on October 30 after cryptocurrency exchange Binance disclosed a security breach involving approximately $6.3 billion in digital assets — potentially the largest cryptocurrency theft in history. The disclosure triggered widespread selling across the crypto market. Binance ranks among the world's largest cryptocurrency exchanges by trading volume, and the news rippled quickly through a market in which a large share of trading activity runs through a handful of centralized platforms.

The sell-off deepened after prediction market Polymarket disclosed a separate security incident. Meanwhile, Standard Chartered cautioned that cryptocurrency prices could face additional declines before a stable recovery takes hold.

Sharp Declines Across Crypto and Crypto-Linked Stocks

Bitcoin dropped approximately 3% to $76,469, its lowest level in six weeks. Ether declined more than 3%, trading near $2,186, as investors reacted to mounting security concerns.

The turmoil extended beyond major tokens, a familiar pattern in which crypto-linked equities tend to trade as proxies for the underlying assets. Shares of Coinbase Global fell 4.8%, while bitcoin-focused Strategy declined nearly 6% in extended U.S. trading. According to Reuters, the Binance incident raised concerns about liquidity, exchange security, and investor confidence, and traders faced uncertainty over whether the disruption could add further selling pressure.

Binance Freezes Roughly $3 Billion in Affected Assets

Binance confirmed that the estimated impact of the incident reached approximately $6.3 billion and worked with blockchain partners to freeze around $3 billion in affected assets, per an official announcement.

Preliminary findings suggest the attackers compromised a DevOps engineer's laptop and gained access to a service container, from which they initiated unauthorized withdrawals. Binance said it found no evidence that wallet private keys had leaked. The account points to a compromise of internal infrastructure and credentials rather than the underlying cryptography that secures on-chain wallets — an operational security risk inherent to centralized venues, which hold customer funds in custody.

The exchange temporarily suspended deposits and withdrawals while conducting security checks and pledged to reimburse affected customers using its Secure Asset Fund for Users (SAFU), an emergency insurance reserve created in 2018, and company resources.

In a separate incident, Polymarket temporarily halted international trading following a breach involving a third-party service provider. The company subsequently restored operations and promised to compensate affected users. Taken together, the back-to-back disclosures showed how quickly security failures — whether inside an exchange or at an outside vendor — can test user confidence across the industry.

Standard Chartered Sees Room for Further Weakness

Geoffrey Kendrick, Standard Chartered's global head of digital assets research, cautioned that the market may experience further declines. He indicated that prices might struggle to establish a reliable bottom until Binance restores access to affected assets and provides additional details about the attack.

Analysts also warned that disruptions at major centralized exchanges could restrict liquidity and increase volatility, though a swift resolution could help stabilize sentiment.

Investors are expected to watch Binance's recovery efforts, the status of the frozen assets, and developments in the ongoing investigation. For now, the $6.3 billion breach has renewed concerns about cryptocurrency custody and exchange security, and the market's recovery may hinge on how quickly Binance restores confidence and normal operations.