A lot of financial institutions are experiencing what is called a Distributed Denial of Service attacks. Do you care to know how this attack operate?
It's an attack where multiple compromised systems -- which are usually infected with a Trojan-- are used to target a single system causing a Denial of Service (DoS) attack. Victims of a DDoS attack consist of both the end targeted system and all systems maliciously used and controlled by the hacker in the distributed attack.
There is so much traffic being sent to the server that legitimate users can not access their service and that's where the terminology come from a Denial of Service Attack.