Former UBS trader Kweku Adoboli, who is accused of unauthorised deals that cost the Swiss bank $2.3 billion (1.4 billion pounds), was refused bail by a London court on Friday.
Adoboli, who last week denied charges of fraud and false accounting relating to the loss, had made his first application to be freed from custody since being arrested last September.
These are serious allegations backed up with cogent evidence, said Judge Alistair McCreath at London's Southwark Crown Court after refusing his application.
Adoboli will remain in custody until his trial which has been set for September 3 this year.
(Reporting by Peter Griffiths,; writing by Michael Holden)