Defence lawyer Patrick Gibbs told City of London Magistrates' Court that Adoboli, 31, "is sorry beyond words for what has happened".
"He went to UBS and told them what he had done, and stands now appalled at the scale of the consequences of his disastrous miscalculations," he said.
Adoboli, smartly dressed in a dark grey suit and dark blue tie, bowed to the court with his hands over his heart as he entered the courtroom and nodded sombrely to people sitting in the public gallery.
Prosecutors said he had been charged with a new count of fraud to add to the existing charge of fraud and and two charges of false accounting.
One of the fraud charges refers to a sum of at least $1.5 billion, but prosecutor David Levy said the Crown Prosecution Service believes the total sum involved was probably $2.3 billion.
Adoboli's lawyer did not request bail and none was granted. He was remanded in custody until October 20th.
He has not entered a plea but is not required to at this stage in the court proceedings.
Adoboli worked for UBS's global synthetic equities division in the City of London financial district.
He bought and sold exchange traded funds, which track different types of stocks or commodities such as precious metals.
He was arrested at UBS's London offices in the early hours of September 15th. Within hours, the bank announced it had lost $2 billion through unauthorised trading, but it later raised the estimated losses to $2.3 billion.
The Wall Street Journal reported on Thursday that British regulators were examining multiple cases of possible improper or unauthorised trading at banks in London.
The report, quoting sources familiar with the matter, said the Financial Services Authority watchdog was building cases against individuals suspected of engaging in improper trading.