Cyber security attacks have wiped at least $52.4 billion (42 billion pounds) off the value of shares in recent years, according to a report published Wednesday.
The study by cyber security consultant CGI and Oxford Economics found that a "significant connection between a severe cyber breach and a company's share price performance" meant that share prices fall 1.8% on average on a permanent basis.
Investors in a typical FTSE 100 company would be worse off by an average of 120 million pounds after a breach, according to the study. The data analyzed 65 "severe" and "catastrophic" cyber security breaches out of a total of 315 breach events since 2013.
Andrew Rogoyski, vice president of cyber security at CGI in the U.K., estimated that "only around 10-20 percent of the major breaches companies suffer in Europe are currently made public, so lost shareholder value across European markets could rise by as much as a factor of 10" when the new regulations force companies to notify users of a breach within 72 hours takes effect in May 2018.
"We are beginning to see city analysts, venture capital firms and credit ratings agencies factor cyber security readiness into the way they assess firms," Rogoyski said in a statement today. "This is positive and should encourage boards across the world to treat cyber security as an enterprise-wide risk."
Oxford Economics collated the data using the Gemalto 'Breach Level Index', which records all disclosed cyber security breaches to have affected listed firms from 2013 to 2016.
Two-thirds of firms suffered an adverse impact on their share price after being targeted by a cyber breach. Financial services were the worst affected, followed closely by communications firms.
"Financial services experience the greatest burden in terms of impact, reflecting the high levels of regulation, the importance of customer confidence and the potential for financial fraud to be a facet of the breach," the report said.
Hacking attacks and other breaches of cyber security have hit companies globally in recent years, from U.S. giant Yahoo to U.K. telecommunications firm TalkTalk in 2015.