The DAO hack - arealive/Viper GitHub Wiki
On June 17, 2016 The DAO was subjected to an attack that exploited a combination of vulnerabilities, including the one concerning recursive calls, and the user gained control of 3.6 million Ether, around a third of the 11.5 million Ether that had been committed to The DAO; the stolen Ether had a value of about $50M at the time of the attack. The funds were put into an account subject to a 28 day holding period under the terms of the Ethereum contract so were not actually gone; members of The DAO and the Ethereum community debated what to do next, with some calling the attack a valid but unethical maneuver, others calling for the Ether to be re-appropriated, and some calling for The DAO to be shut down.1
[1] https://en.wikipedia.org/wiki/The_DAO_(organization)#History