France's second largest bank, Societe Generale, has filed a legal complaint against the trader accused of defrauding the bank which led to a loss of 4.9bn euros ($7.1bn). The bank says the trader acted alone. This report from Alasdair Sandford:

Listen to the story

Societe Generale described his motives as "totally irrational" and admitted it didn't know where the man was. A number of managers are also being dismissed and the bank was forced into an emergency share issue to offset the losses.

One of the executives who interviewed the trader said it would have been impossible for him to have acted with accomplices. But analysts are mystified as to how losses the bank itself described as "colossal" could have gone undetected: one said the market was suspicious that there was something more sinister at play.

Alasdair Sandford, BBC News, Paris

Listen to the words

futures
agreements for the buying and selling of large quantities of goods in which the price is agreed in advance of a particular time in the future

suspended
told not to come to work (temporarily)

motives
reasons for doing something

was forced into
had no other choice but to introduce

offset
balance one thing against another (often its opposite), so it has no great effect

accomplices
people who help someone else to do something that is illegal or morally wrong

are mystified
have no idea, don't understand

colossal
huge, extremely large

gone undetected
not been noticed

there was something more sinister at play
there was another very bad or evil reason involved

Read more about this story