Data breaches and hacking have become a fact of life but the one reported by US credit-reporting agency Equifax last week could be one of the worst to date. The data of 143m Americans, including addresses, dates of birth, driving license numbers and, crucially, social security numbers, was stolen by hackers and the company is now facing regulatory investigation and class action lawsuits due to the sensitivity of the information hacked. This is all going to be costly for Equifax – and its shares are down over 20% since they revealed the extent of the hack. Data from the Ponemon Institute, a data-protection research firm, shows that in 2017 lost business and legal costs accounted for most of the costs for US companies hit by data breaches. And Equifax is likely to face a significant legal bill and a big loss of trust in its data gathering services as a result of this latest hack.