Binance’s $6.3 billion hack raises questions about crypto wallet safety

A bitcoin automated teller machine (ATM) stands at the Coin Trader bitcoin retail store in Tokyo, Japan, on Wednesday, Aug. 30, 2017. Stock of Bitcoin, the best-known digital currency, has surged 358 percent this year. While staggering, lesser-known competitors have seen even bigger gains, such as the more than 4,000 percent increase for ethereum. Photographer: Tomohiro Ohsumi/Bloomberg via Getty ImagesBloomberg | Bloomberg | Getty ImagesTwo high-profile security breaches this week – including the biggest cryptocurrency theft in history – are raising questions on the safety of storing funds in a wallet on a crypto exchange.A security incident at digital asset exchange Binance on Thursday affected some $6.3 billion in client assets, making it the largest crypto theft on record. Earlier that day, prediction market platform Polymarket temporarily halted trading on its international exchange after a third-party data provider was hacked, resulting in at least $2.7 million being drained from users' wallets. The company's international platform operates on the Polygon blockchain. Experts whom CNBC interviewed said the security incidents on the crypto exchanges aren't surprising, especiall...