More than $1 billion of ether has been lost forever due to bugs and human error, according to research by Conor Grogan, director of product strategy and business operations at Coinbase. 

"I've categorized thousands of instances of Ethereum typos, user errors and buggy contracts," Grogan said on Twitter on Monday. He noted that he'd cataloged 636,000 ETH ($1.15 billion) that is lost, representing 0.5% of the coin's circulating supply.

Roughly half that total — some 306,000 ETH — is due to a 2017 bug in the Parity crypto wallet. Defunct crypto exchange Quadriga lost 60,000 ETH to a contract fault and the Akutars NFT collection lost 11,500 ETH in a failed Mint. On top of those, Ethereum users have cumulatively sent 24,000 ETH to a burn address, where the coins can no longer be accessed.

(By Tim Copeland)