That's what mtgox said too, I believe their figure was 98%: On average 98% of customer bitcoins are held in cold storage...Offline wallets are generated from a

That's what mtgox said too, I believe their figure was 98%: On average 98% of customer bitcoins are held in cold storage...Offline wallets are generated from an offline system and kept in paper format in three separate locations, using a technology based on raid. https://bitcointalk.org/index.php?topic=23938.40 https://bitcointalk.org/index.php?topic=23938.40 http://www.managementtoday.co.uk/bulletin/mtdailybulletin/article/1282210/this-end-bitcoin-mtgox-goes-offline/ http://www.managementtoday.co.uk/bulletin/mtdailybulletin/ar... But of course, they weren't really in cold storage or offline after all, because somehow they all disappeared... Not that I mistrust coinbase specifically, but without insurance, audits and regulation (i.e. without a banking license), I'm not sure I'd trust anyone to store significant amounts of money.