Deloitte

One of the world’s “big four” accountancy firms has been targeted by a sophisticated hack that compromised the confidential emails and plans of some of its blue-chip clients.
Deloitte, which is registered in London and has its global headquarters in New York, was the victim of a cybersecurity attack that went unnoticed for months.
In 2012, Deloitte, which has offices all over the world, was ranked the best cybersecurity consultant in the world.

Source : Deloitte hit by cyber-attack revealing clients’ secret emails | Business | The Guardian